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The study was focused on the anatomical characteristics of the Egyptian long-eared hedgehog's oral cavity by using gross and scanning electron microscopic examinations. The upper lip had an elongated T-shaped snout-like structure. The hard palate had a triangular rostral part (which had a semicircular area and a caudal ridged area with the first 3 or 4 ridges) and a caudal part (which contained seven or eight slightly oblique ridges with raphae). The diamond-incisive papilla is flanked on both sides by a groove and a fissure. The hard palate surface had glandular openings and a microplicae system. The uneven, soft palate's surface had multiple grooves and folds with 12-16 Gemmal papillae. The Gemmal papillary surface had three to four taste pores with microplicae and glandular openings. The dorsal lingual surface had six filiform subtypes: pointed (on the tip, rostral border, and median apical region), triangular (on the lateral apical and circumvallate regions), bifurcated (on the median tip only), leaf-like (on the median body region), branched (on the lateral root region), and small pointed papillae (on the median root). There were two fungiform subtypes: ovals (on the rostral border and lateral region) and rounds (on the median apical region and body). The caudal root part had a triangular arrangement of three circumvallate papillae. In conclusion, the finding confirmed its oral cavity adaptation with its insectivorous feeding habits and Egyptian environment., (© 2024. The Author(s).)

Background: European hedgehogs (Erinaceus europaeus) are small insectivorous mammals common in Europe. With increased urbanization, the species become more frequent in the cities and near other human dwellings. The anatomy of the species with the use of diagnostic imaging techniques along with the classical anatomical methodology has not been researched before. In addition to the description of this species' skull, the data may contribute to progress in hedgehog medicine, delivering a basis for diagnosing and treating head trauma in this species., Results: Cadavers of 30 European hedgehogs have been used to study the anatomy of the head of the species. Along with classical anatomical techniques - latex and corrosion cast specimens, x-ray, and cone-bean computed tomography scans were performed. The methods were then compared, and the detailed anatomy of the head was described. The skull of the Western European hedgehog was elongated and oval in shape, and could be divided into two distinct regions: one formed of neurocranial bones and the other of facial bones. The neurocranium was composed of the following bones: the occipital, interparietal, parietal, frontal, temporal, sphenoid, ethmoid, and pterygoid bones. The following facial bones were identified: the incisive, nasal, maxilla, zygomatic, palatine, vomer, and the mandible. The most important findings include the primitive tympanic bullae, the absence of a supraorbital foramen, and the lacrimal bones, which were indistinguishably fused with the maxillae., Conclusions: The results of the study may be used in future research on the comparative anatomy of the other members of the Eulipotyphla order. With the increase of hedgehogs in the cities, it is important to establish new diagnostic and treatment protocols for wildlife rehabilitation centers. Anatomical and radiological descriptions may be used as a base for such work. The anatomical features of the hedgehog skull described in the study may prove useful for further studies from a comparative anatomical perspective. Additionally, the data may serve as a basis for developing identification guidelines for archaeological studies and forensic research., (© 2024. The Author(s).)

One crucial component of the optical system is the ciliary body (CB). This body secretes the aqueous humour, which is essential to maintain the internal eye pressure as well as the clearness of the lens and cornea. The histological study was designed to provide the morphological differences of CB and iris in the anterior eye chambers of the following vertebrate classes: fish (grass carp), amphibians (Arabian toad), reptiles (semiaquatic turtle, fan-footed gecko, ocellated skink, Egyptian spiny-tailed lizard, Arabian horned viper), birds (common pigeon, common quail, common kestrel), and mammals (BALB/c mouse, rabbit, golden hamster, desert hedgehog, lesser Egyptian jerboa, Egyptian fruit bat). The results showed distinct morphological appearances of the CB and iris in each species, ranging from fish to mammals. The present comparative study concluded that the morphological structure of the CB and iris is the adaptation of species to either their lifestyle or survival in specific habitats., (© 2024 Wiley‐VCH GmbH. Published by John Wiley & Sons Ltd.)

This study aimed to assess the numbers of juvenile European hedgehogs admitted to rescue centers in the Czech Republic from the viewpoint of their weight on admission, the reason for their admission, and the success rate of their release back into the wild. The results of our study show varying levels of success in the rearing of hedgehogs admitted at different ages (weights) and a varying period required for their rehabilitation. The greatest chance of release was seen in hedgehogs with a weight on the admission of 500-599 g (64.22% released) and 400-499 g (63.31% released). In contrast, the smallest number of young hedgehogs successfully rehabilitated and released was seen in hoglets weighing 200-299 g (35.24% released) on admission, which corresponds to the weight of hedgehogs at the time of weaning. Time spent at a rescue center may pose an undesirable threat to the lives of animals in some categories. Hedgehogs weighing up to 99 g on admission spent the longest period time at rescue centers (a median of 48 days), while hedgehogs weighing 500-599 g on admission spent the shortest time (a median of 7 days). The majority of hedgehogs in the lowest weight categories were admitted due to their inability to survive on their own. A large percentage of hedgehogs of greater weight, in contrast, were juvenile hedgehogs brought to rescue centers needlessly. The percentage of released animals did not exceed 65%, however, even for entirely independent categories of older juveniles. From this perspective, the fact that hedgehogs are often brought to rescue centers in the belief that they are not self-sufficient young, though they are actually juvenile or even adult individuals that do not require human care, can be considered a significant finding., Competing Interests: The authors have declared that no competing interests exist.

Bioluminescence has been recognized as an important means for inter- and intra-species communication. A growing number of reports of red fluorescence occurring in keratinaceous materials have become available. The fluorophore(s) in these cases were shown to be, or suspected to be, free base porphyrins. The red fluorescence found in the downs of bustards was associated with inter-species signaling in mate selection. First reported in 1925, we confirm that spines of the European hedgehog (Erinaceus europaeus) when irradiated with UV (365-395 nm) light display red fluorescence localized in the light-colored sections of their proximal ends. Using reflectance fluorescence spectroscopy, we confirmed that the fluorophores responsible for the emission are free-base porphyrins, as suspected in the original report. Base-induced degradation of the spine matrix and subsequent HPLC, UV-vis, and ESI+ mass spectrometry analysis revealed the presence of a mixture of coproporphyrin III and uroporphyrin III as predominant porphyrins and a minor fraction of protoporphyrin IX. Investigation of the spine microbiome uncovered the abundant presence of bacteria known to secrete and/or interconvert porphyrins and that are not present on the non-fluorescing quills of the North American porcupine (Erethizon dorsatum). Given this circumstantial evidence, we propose the porphyrins could originate from commensal bacteria. Furthermore, we hypothesize that the fluorescence may be incidental and of no biological function for the hedgehog.

The tongue of the lesser hedgehog tenrec (Echinops telfairi) was evaluated by light and scanning electron microscopy. Dorsal and lateral surfaces of the tongue were densely covered with various types of lingual papillae. Two types of mechanical papillae (filiform and conical) and two types of sensory papillae (fungiform and vallate) were observed. Rostrocaudally, the number of spikes in filiform papillae increased. Filiform, crown-like papillae were found on the radix, as well as large conical papillae with a wide base and a caudally bent single spike. Fungiform papillae were scattered in four rows on the dorsal surface. Three vallate papillae in inverse triangular layout were developed in the area of the lingual radix. Taste buds were found in the sensory papillae, i.e., fungiform and vallate. The lingual glands were predominantly seromucous. These glands were evenly scattered from the caudal portion of the lingual apex to the lingual radix. Purely serous glands were localized close to vallate papillae. A histochemical analysis of glands was performed. Results were compared to the Afrotheria (tenrec's relatives) and Eulipotyphla (animals with similar feeding habits to tenrecs). This study is the first description of the lingual morphology in the member of the Order Afrosoricida. Moreover, it compares the effect of the phylogenetic relation to the effect of the feeding habits on the lingual morphology.

Background: The current study represents the first description of the histological characterisations of the normal skin of Brandt's hedgehog (paraechinus hypomelas)., Materials and Methods: Skin samples were collected from abdomen, back, nostril and cloacal regions., Results: The skin consisted of 3 layers including epidermis, dermis and hypodermis. The epidermis was covered by a layer of keratinised squamous epithelium mainly in the back region, but the skin keratinisation was present with a little amount or may was absent in other regions. Histologically, the total thickness of skin was maximum on the back and minimum on the cloacal regions. The epidermis consisted of 4 layers and stratum lucidum was absent in all regions. Beneath the epidermis, the dermis layer was constituted of dense connective tissue in which the hair follicles, sweat glands, sebaceous glands, arrector pilli muscles and blood vessels were present. The sweat and sebaceous glands were more populated in the nostril region. The hair follicles were located in the epidermal and dermal regions. Vibrissae were only in the nostrils region and characterised from other hairs by their large and well innervated hair follicle which was surrounded by the blood sinus., Conclusions: The present findings show that in Brandt's hedgehog (paraechinus hypomelas) the back and cloacal regions have thickest and thinnest skin respectively as compared to the nostril and abdominal regions. In addition, sebaceous and sweat glands were mainly populated in the nostril region.

The current study aimed to describe the anatomical features of the tongues of two micro-mammals common in the Egyptian fauna; the Nile grass rat (Arvicathis niloticus), and the Egyptian long-eared hedgehog (Hemiechinus auritus). The tongues of five adult individuals of each species were excised and processed histologically, histochemically, and morphometrically. Statistical analysis comparing the relative tongue length in both species showed that there was a significant difference, which may correlate with the difference in feeding preferences. Grossly, the Nile grass rat has a dorsal lingual prominence with bifurcated apex while, the long-eared hedgehog has a median slight elevation with rounded apex. Numerous forms of mechanical and gustatory papillae are scattered along the lingual dorsal epithelium. The histochemical detection of keratin by Holland's trichrome stain showed an intense expression in the case of A. niloticus and mild expression in H. auritus. The framework of the tongue (entoglossum) is supported by either a core of cartilage in H. auritus or bone in A. niloticus which incorporated in the lingual root. The lingual glands also showed marked variation, the Nile grass rat exhibit dense populations of mucous-secreting glands and lesser populations of serous-secreting glands, the contrary is true in H. auritus. In conclusion, the micro and macro-anatomical features of the tongues of both species showed adaptive changes to accommodate the feeding lifestyle. Such type of studies using mammals from different phylogenetic traits and almost have different feeding preferences provide answers to many research questions related to tongue evolution among mammalian vertebrates., (© 2019 Wiley Periodicals, Inc.)

Author examined the dorsal lingual surfaces of the adult Japanese lesser flying squirrel (Pteromys momonga) and four-toed hedgehog (Atelerix albiventris) by scanning electron microscopy. In the Japanese lesser flying squirrel, the filiform papilla of the lingual body consisted of a large conical papilla. The filiform papilla of the lingual prominence was spoon in shape. The fungiform papillae were round in shape and scattered among the filiform papillae. Many foliate papillae were observed on the posterolateral regions of the lingual body. The foliate papillae had some ridges separated by deep grooves. The vallate papilla was located between lingual body and root. Several long conical papillae derived from the posterolateral margin of the tongue. In the four-toed hedgehog, the filiform papilla of the lingual apex had a conical process. The filiform papilla of the lingual body had some processes. The fungiform papillae were round in shape. The foliate papillae were observed on the posterolateral regions of the lingual body. The papilla was separated from each other by a furrow. The vallate papilla consisted of a central papilla and an annular pad. These findings suggest that in the structure of the lingual papillae of the Japanese lesser flying squirrel there is similar to that of the sugar glider and the lingual papillae of the four-toed hedgehog is different from that of the Japanese lesser flying squirrel.

Hedgehogs in the genus Mesechinus (Family Erinaceidae), which include two currently recognized species ( M. dauuricus and M. hughi ), are distributed from northeast Mongolia to the upper Amur Basin in Russia and adjacent areas in northeast and northern China. In recent years, a population of Mesechinus hedgehogs was discovered from Mt. Gaoligong, southwestern Yunnan, China, far from the known distribution range of the genus. Furthermore, these hedgehogs are the only known population to be distributed at elevations higher than 2 100 m and in sympatry with gymnures. To evaluate the taxonomic status of these hedgehogs, we examined specimens representing Mesechinus taxa in China and further conducted morphometric and karyotypic analyses. Our results supported the existence of four species in China. Specifically, we identified the hedgehogs from Mt. Gaoligong as a new species, Mesechinus wangi sp. nov., and recognized M. miodon , previously considered as a synonym of either M. dauuricus or M. hughi , as a distinct species. Interestingly, we observed a supernumerary M 4 on all specimens of Mesechinus wangi sp. nov., which is an extremely rare event in the evolution of mammalian dentition.

The hedgehog tongue is a tactile and taste organ which carries out various functions. Detailed functional and morphological studies are required to clearly define the relationship of the hedgehog tongue with taste, food palatability, mastication and swallowing of food, as well as the production of sounds. The aim of this study was to determine the relationship between the morphological characteristics of the European hedgehog tongue and the lifestyle of this animal, as well as to compare findings with the results of studies on other vertebrates. Gross and micro-anatomical light and scanning electron microscopy studies revealed that the hedgehog tongue could be divided in three areas, namely the apex, body and root. A keratinized stratified squamous epithelium, which was smooth on the ventral surface but bore four types of papillae on the dorsal surface, lined the tongue. Three types of these papillae were found to have gustatory functions and to express their activity in close relation with the salivary glands. These simple conical filiform papillae were situated caudally and distributed one after the other without a break. The dome-shaped fungiform papillae on the apex, with the highest distribution rate on the apex edge, were small, but those on the body and root were large. The three circular vallate papillae were arranged in a triangular shape. The foliate papillae with a few tiny projections, found in a shallow furrow, were situated between the root and the body. Most of the nerve fibers observed in different sections of the tongue tissue were of the unmyelinated type, confirming that the main task of the hedgehog tongue was its gustatory function.

Hedgehogs are small spiny-coated insectivores. Due to their low body weight, calm character, and easy maintenance, they are kept as pets. It is therefore worthwhile to care about hedgehogs' health problems and to provide pet owners with information about their reproduction. Moreover, it is necessary to be familiar with their anatomy so as to satisfy the need to improve nutrition and medical care, even surgery. This study was carried out on five adult male European hedgehogs euthanased in a chloroform chamber. The European hedgehog's oval testes are invisible in inguinal region because they have no true scrotal sac. The testes are located in the craniocaudal direction with dorsolateral epididymal attachments. The vesicular glands, the European hedgehog's largest accessory sex glands, are lobulated structures containing dorsomedial and ventrolateral parts on each side. The prostate is an oval gland with right and left lobes. The paired bulbourethral glands are laid on the ischiocavernosus muscle. Histologically the vesicular, prostate gland ducts and ductus deferens as well as urethra separately were discharged in a diverticlum at the level of the pelvic urethra end. A sigmoid flexure exists in the proximal part of shaft body of the penis. There are two retractor penile muscles. In dorsal end of the penile glans, there is a small urethral process with two nail- -like, needle-shaped structures. They are on both sides of the urethral process. Furthermore, there are two intromittent sacs (Sacculus urethralis) in the ventral part of the end of the penis. (Folia Morphol 2018; 77, 1: 36-43).

Unusual mammalian species such as the hedgehog, sugar glider, and miniature pig are encountered with increasing frequency in exotic companion medicine. Disease of the oral cavity can occur in any species; although occasionally encountered in exotic mammalian species, it is rarely described in the literature. Anatomy and dentition vary significantly; diagnosis and treatment are often extrapolated from that known in other species. The best-documented disease of the oral cavity in this group of species is oral neoplasia in the hedgehog., (Copyright © 2016 Elsevier Inc. All rights reserved.)

Jaculus jaculus (Lesser Egyptian jerboa) and Paraechinus aethiopicus (Desert hedgehog) are small mammals which thrive in desert conditions and are found, among others, in the Arabian Peninsula. Jaculus jaculus is omnivorous while P. aethiopicus is described as being insectivorous. The study aims to describe the gastrointestinal tract (GIT) morphology of these animals which differ in diet and phylogeny. The GITs of J. jaculus (n = 8) and P. aethiopicus (n = 7) were weighed, photographed, and the length, basal surface areas, and luminal surface areas of each of the anatomically distinct gastrointestinal segments were determined. The internal aspects of each area were examined and photographed while representative histological sections of each area were processed to wax and stained using haematoxylin and eosin. Both species had a simple unilocular stomach which was confirmed as wholly glandular on histology sections. Paraechinus aethiopicus had a relatively simple GIT which lacked a caecum. The caecum of J. jaculus was elongated, terminating in a narrow cecal appendix which contained lymphoid tissue on histological examination. The internal aspect of the proximal colon of J. jaculus revealed distinct V-shaped folds. Stomach content analysis of J. jaculus revealed mostly plant and seed material and some insects, whereas P. aethiopicus samples showed plant material in addition to insects, indicating omnivorous feeding tendencies in areas where insects may be scarce., (© 2016 Wiley Periodicals, Inc.)

The organization of the cholinergic, catecholaminergic, and serotonergic neurons in the brains of five species of insectivores and the orexinergic (hypocretinergic) system in four insectivore species is presented. We aimed to investigate the nuclear complement of these neural systems in comparison to those of other mammalian species. Brains of insectivores were coronally sectioned and immunohistochemically stained with antibodies against choline acetyltransferase, tyrosine hydroxylase, serotonin and orexin-A. The majority of nuclei were similar among the species investigated and to mammals in general, but certain differences in the nuclear complement highlighted potential phylogenetic interrelationships. In the cholinergic system, the three shrew species lacked parabigeminal and Edinger-Westphal nuclei. In addition, the appearance of the laterodorsal tegmental nucleus in all insectivores revealed a mediodorsal arch. All three of these features are the same as those present in microchiropterans. The catecholaminergic system of the three shrew species lacked the A4 and A15d nuclei, as well as having an incipient A9v nucleus, again features found in microchiropteran brains. The serotonergic and orexinergic systems of the insectivores are similar to those seen across most eutherian mammals. The analysis of similarities and differences across mammalian species indicates a potential phylogenetic relationship between the Soricidae (shrews) and the microchiropterans., (Copyright © 2015 Elsevier B.V. All rights reserved.)

A 2-year-old female African hedgehog was presented with a 5-month history of pruritus, and diffuse spine and hair loss. A dermatologic examination revealed erythema, excoriation, scales, and crusting affecting the face, flanks, forelimbs, hindlimbs, and dorsal and ventral abdomen. Fine-needle aspiration was performed and skin biopsies were taken from several lesions for cytologic and histologic evaluation. The aspirates yielded smears characterized by a monomorphic population of medium-sized to large lymphocytes with scant to moderate amounts of clear to moderately basophilic cytoplasm and distinct nucleoli along with a low number of cytoplasmic fragments. On histopathologic examination, there were dense dermal lymphoid infiltrates invading the dermis and a monomorphic population of round cells that had infiltrated the overlying epidermis. Epitheliotropic cutaneous lymphoma was diagnosed based on morphologic features. Additional immunochemical analysis using anti-CD3 and anti-CD79a antibodies revealed strong CD3 expression by the tumor cells, which confirmed epitheliotropic cutaneous T-cell lymphoma. This is the first description of a multicentric pattern of epitheliotropic cutaneous T-cell lymphoma in an African hedgehog., (© 2014 American Society for Veterinary Clinical Pathology.)

Placentation determines the developmental status of the neonate, which can be considered as the most vulnerable stage in the mammalian life cycle. In this respect, the different evolutionary and ecological adaptations of marsupial and placental mammals have most likely been associated with the different reproductive strategies of the two therian clades. The morphotypes of marsupial and placental neonates, as well as the placental stem species pattern of Marsupialia, have already been reconstructed. To contribute to a better understanding of the evolution of Placentalia, a histological and ultrastructural investigation of the placenta in three representatives of Eulipotyphla, that is, core insectivores, has been carried out in this study. We studied the Musk shrew (Suncus murinus), the four-toed hedgehog (Atelerix albiventris), and the Iberian mole (Talpa occidentalis). As a result, a eulipotyphlan placental morphotype consisting of a compact and invasive placenta was reconstructed. This supports the widely accepted hypothesis that the stem lineage of Placentalia is characterized by an invasive, either endothelio- or hemochorial placenta. Evolutionary transformations toward a diffuse, noninvasive placenta occurred in the stem lineages of lower primates and cetartiodactyles and were associated with prolonged gestation and the production of few and highly precocial neonates. Compared to the choriovitelline placenta of Marsupialia, the chorioallantoic placenta of Placentalia allows for a more intimate contact and is associated with more advanced neonates., (© 2014 Wiley Periodicals, Inc.)

We investigated adult neurogenesis in two species of mammals belonging to the superorder Laurasiatheria, the southern white-breasted hedgehog (order Erinaceomorpha, species Erinaceus concolor) from Armenia and the European mole (order Soricomorpha, species Talpa europaea) from Poland. Neurogenesis in the brain of these species was examined immunohistochemically, using the endogenous markers doublecortin (DCX) and Ki-67, which are highly conserved among species. We found that in both the hedgehog and mole, like in the majority of earlier investigated mammals, neurogenesis continues in the subventricular zone (SVZ) of the lateral ventricles and in the dentate gyrus (DG). In the DG of both species, DCX-expressing cells and Ki-67-labeled cells were present in the subgranular and granular layers. In the mole, a strong bundle of DCX-labeled processes, presumably axons of granule cells, was observed in the center of the hilus. Proliferating cells (expressing Ki-67) were identified in the SVZ of lateral ventricles of both species, but neuronal precursor cells (expressing DCX) were also observed in the olfactory bulb (OB). In both species, the vast majority of cells expressing DCX in the OB were granule cells with radially orientated dendrites, although some periglomerular cells surrounding the glomeruli were also labeled. In addition, this paper is the first to show DCX-labeled fibers in the anterior commissure of the hedgehog and mole. These fibers must be axons of new neurons making interhemispheric connections between the two OB or piriform (olfactory) cortices. DCX-expressing neurons were observed in the striatum and piriform cortex of both hedgehog and mole. We postulate that in both species a fraction of cells newly generated in the SVZ migrates along the rostral migratory stream to the piriform cortex. This pattern of migration resembles that of the 'second-wave neurons' generated during embryonal development of the neocortex rather than the pattern observed during development of the allocortex. In spite of the presence of glial cells alongside DCX-expressing cells, we never found colocalization of DCX protein with a glial marker (vimentin or glial fibrillary acidic protein)., (Copyright © 2010 S. Karger AG, Basel.)

The normal radiographic anatomy of the healthy hedgehog can help to identify anatomic features unique to the hedgehog while comparing it with other small mammals, such as the dog and cat. Radiographic examination is a method that can play an important role in the diagnosis of a wide variety of skeletal diseases. Seven (2 males, 5 females) free-living hedgehogs (Erinaceus concolor) from the Urmia region of Iran were selected for this study. Lateral and craniocaudal radiographs from the front and hind limbs were obtained. The radiographs from these hedgehogs were compared with the normal canine and feline skeletal radiographic anatomy. On the forelimb radiographs, the clavicle was observed as a complete bone connected to the scapula and manubrium. There are three and five carpal bones in the proximal and distal rows, respectively, as in the dog and cat. The pelvis has a larger obturator foramen when compared with the dog and cat. In the lateral view, the pubis and ischium are relatively larger than in the dog and cat and have a more ventral position. The tarsal bones are similar to those of the dog and cat. The number of phalanges and sesamoid bones in the forelimb and hindlimb are likewise similar to those found in the dog and cat.

The present study examines comparatively the cellular density of disector-counted/Nissl-stained CA1 pyramidal neurons and the morphometric characteristics (dendritic number/length, spine number/density and Sholl-counted dendritic branch points/20 microm) of the basal and apical dendritic systems of Golgi-impregnated CA1 neurons, in the septal and temporal hippocampus of the human and hedgehog tenrec brain. The obtained results indicate that in both hippocampal parts the cellular density of the CA1 pyramidal neurons is lower in human than in tenrec. However, while the human pyramidal cell density is higher in the septal hippocampal part than in the temporal one, in the tenrec the density of these cells is higher in the temporal part. The dendritic tree of the CA1 pyramidal cells, more developed in the septal than in temporal hippocampus in both species studied, is in general more complex in the human hippocampus. The basal and the apical dendritic systems exhibit species related morphometric differences, while dendrites of different orders exhibit differences in their number and length, and in their spine density. Finally, in both species, as well as hippocampal parts and dendritic systems, changes of dendritic morphometric features along ascending dendritic orders fluctuate in a similar way, as do the number of dendritic branch points in relation to the distance from the neuron soma.

Karyological features of Erinaceus concolor and Hemiechinus auritus were studied from Zenjan (North Iran). The diploid number of chromosomes (2n), the total numbers of chromosomal arms (NF) and the numbers of autosomal arms (NFa) were determined as 2n = 48, NF = 92, NFa = 88 for E. concolor and as 2n = 50, NF = 98, NFa = 94 for H. auritus. Although the same dental formulae were established as 3.1.3.3/2.1.2.3 = 36 for both of species, they can be identified with some dental and cranial features from each other. Additionally, phallus of E. concolor was described.

Although insectivores have traditionally been thought of as primitive mammals with few specializations, recent studies have revealed great diversity in the sensory systems and brain organization of members of this mammalian order. The present article reviews some of these findings in three insectivore families that are thought to form a monophyletic group. These include hedgehogs (Erinaceidae), moles (Talpidae), and shrews (Soricidae). Members of each group live in unique ecological niches, have differently specialized senses, and exhibit different behaviors. Hedgehogs have well-developed visual, auditory, and somatosensory systems. Shrews make use of visual and auditory cues, but appear to depend most heavily on touch, particularly through prominent vibrissae. Moles are somatosensory specialists with small eyes and ears and unique epidermal mechanoreceptors called Eimer's organs used to identify prey and investigate their environment. In contrast to historical views of the insectivore order, members of this group have discrete and well-organized cortical sensory areas with sharp borders as determined from both electrophysiological mapping and analysis of cortical histology. Comparison of cortical organization across species reveals a number of specializations, including expansion of cortical representations of important sensory surfaces, the addition of cortical areas to some processing networks, and the subdivision of areas into separate cortical modules. In the case of the star-nosed mole, the somatosensory system has a tactile fovea and shares a number of features in common with the visual systems of sighted mammals., ((c) 2005 Wiley-Liss, Inc.)

We immunohistochemically examined the organization of the main olfactory bulbs (MOBs) in seven mammalian species, including moles, hedgehogs, tree shrews, bats, and mice as well as laboratory musk shrews and rats. We focused our investigation on two points: 1) whether nidi, particular spheroidal synaptic regions subjacent to glomeruli, which we previously reported for the laboratory musk shrew MOBs, are also present in other animals and 2) whether the compartmental organization of glomeruli and two types of periglomerular cells we proposed for the rat MOBs are general in other animals. The general laminar pattern was similar among these seven species, but discrete nidi and the nidal layer were recognized only in two insectivores, namely, the mole and laboratory musk shrew. Olfactory marker protein-immunoreactive (OMP-IR) axons extended beyond the limits of the glomerular layer (GL) into the superficial region of the external plexiform layer (EPL) or the nidal layer in the laboratory musk shrew, mole, hedgehog, and tree shrew but not in bat, mouse, and rat. We observed, in nidi and the nidal layer in the mole and laboratory musk shrew MOBs, only a few OMP-IR axons. In the hedgehog, another insectivore, OMP-IR processes extending from the glomeruli were scattered and intermingled with calbindin D28k-IR cells at the border between the GL and the EPL. In the superficial region of the EPL of the tree shrew MOBs, there were a small number of tiny glomerulus-like spheroidal structures where OMP-IR axons protruding from glomeruli were intermingled with dendritic branches of surrounding calbindin D28k-IR cells. Furthermore, we recognized the compartmental organization of glomeruli and two types of periglomerular cells in the MOBs of all of the mammals we examined. These structural features are therefore considered to be common and important organizational principles of the MOBs., (Copyright 2004 Wiley-Liss, Inc.)

The distribution of vasoactive intestinal polypeptide (VIP)-immunopositive elements was analyzed in the olfactory bulb (OB) of the Western European hedgehog (Erinaceus europaeus) under light and electron microscopy. The immunoreactivity appeared in an abundant population of periglomerular cells of the glomerular layer, in interneurons of the external plexiform layer, and in a restricted group of deep short-axon cells of the internal plexiform layer, the granule cell layer and the white matter. In the glomerular layer, VIP-containing periglomerular cells constituted a population of non-GABAergic neurons and did not receive synapses from olfactory axons. In the EPL, VIP-immunoreactivity appeared in a morphologically heterogeneous population of GABAergic interneurons, most of them identified as satellite cells and Van Gehuchten cells. These interneurons exerted an abundant and selective innervation of the somata, primary and secondary dendrites of the principal mitral and tufted cells, but did not contact granule cells. Perisomatic innervation of the principal cells followed two different patterns. The first included 'normal' basket-like arrangements of VIP-containing varicosities surrounding the somata of mitral and tufted cells. In the second, a set of satellite cells gave rise to short dendritic shafts that embraced the somata of principal cells in an 'exuberant' basket-like arrangement. These two morphological patterns of perisomatic innervation of principal cells were correlated with a neurochemical specificity of the target. In this sense, the 'exuberant' basket-like structures were always found surrounding a subpopulation of principal cells that did not contain the calcium-binding protein parvalbumin (PV). By contrast, they were never found surrounding the subpopulation of PV-containing principal cells, which only showed 'normal' basket-like structures. This study provides new data on the connectivity and neurochemical features of the hedgehog olfactory bulb and suggests that the olfactory circuits in this species are more complex than those described in other mammals.

Cyto- and chemoarchitectural findings have recently suggested that in the hedgehog tenrec, the claustrum is not located below but between the layers of the rhinal/insular cortex (Künzle and Radtke-Schuller 2000b). The present connectional study confirms this unusual position. Tracer injections were made into various isocortical and allocortical regions. They showed that the tenrec's dorsal claustrum was reciprocally and bilaterally connected with the neocortex. The ventral claustrum was connected with mainly the ipsilateral paleocortex, additionally with the ventromedial frontal cortex and possibly the subiculum. A sparsely labeled cell group separated the claustrum from the labeled cells located in the depth of the RCx and the adjacent paleo- and neocortices. On the basis of the linear arrangement of these latter cells immediately adjacent to the subcortical white matter, and the restriction of their labeling to the ipsilateral side, one might interpret preliminarily these cells as layer 6B cells or persisting subplate neurons. Their cortical projections showed a similar topographic organization as the claustro-cortical projections. The unusual features described in tenrec were discussed with respect to similar organizations in other mammals with poorly differentiated brains and compared with embryonic brains of mammals with more differentiated brains.

The rhinal cortex was investigated in the Madagascan lesser hedgehog tenrec, a basal placental mammal. This region parallels the rhinal indentation and presumably contains the equivalents of the insular and perirhinal cortices. Using cyto- and myeloarchitectural, enzyme- and immunohistochemical criteria as well as data on the connections with the olfactory bulb, the rhinal cortex was subdivided tentatively along its rostrocaudal and dorsoventral planes. An area caudally adjacent to the rhinal cortex received a prominent input from the olfactory bulb and was also preliminarily characterized in this study. Because previous studies in insectivores remained controversial with regard to the identification of the claustrum, special attention was paid to the laminar organization of the rhinal cortex and its deep cell groups. The tenrec's claustrum was identified and delineated cytoarchitecturally and by its negative acetylcholinesterase stain. Latexin, a molecular marker for characterizing infragranular and claustral cells, also helped to differentiate the claustrum from the cell groups subjacent to it. Thus, the data indicate that in poorly differentiated mammals the claustrum occupies an intermediate deep position within the width of the rhinal cortex, i.e., it is separated from the subcortical white matter by additional, still unidentified, cell groups.

In the Madagascan hedgehog tenrec, Echinops telfairi, the entire paleocortical region (PCx) subjacent to the rhinal indentation is composed of three layers and occupies up to two thirds of the lateral hemisphere. A clear differentiation of PCx into its presumed constituents, the piriform cortex and the entorhinal cortex, as seen in other mammals, has not been obtained so far. To gain insight into location and intrinsic organization of these areas in a basal placental mammal we investigated the tenrec's PCx using cyto-, myelo- and chemoarchitectural criteria (zinc, acetylcholinesterase, NADPh-diaphorase, Wisteria floribunda agglutinin, parvalbumin, calbindin, calretinin) and analysed its connections with the olfactory bulb. The layers 2 and 3 of the tenrec's PCx differed from the corresponding layers in the rat. The layer 2 showed a complex distribution of corticobulbar cells but could not be subdivided, in contrast to layer 3. Additional cell groups in the depth of PCx were tentatively compared with subdivisions of the endopiriform region. The architectural and connectional features varied clearly along the rostrocaudal and dorso-ventral extents of PCx and gave hints for the presence of different paleocortical subdivisions. With the possible exception of an area located at the most caudal tip of the dorsomedial hemisphere, however, no conclusive evidence was obtained for the presence of a multilayered, entorhinal region. The bulbar projections to the PCx were very extensive and almost exclusively ipsilateral. The laterality of the projection is similar to that in higher mammals, but differs from that in the erinaceous hedgehog.

In an attempt to gain insight into the organization and evolution of the basal forebrain, the region was analysed cytoarchitecturally, chemoarchitecturally, and hodologically in a lower placental mammal, the lesser hedgehog tenrec. Particular emphasis was laid on the subdivision of the olfactory tubercle, the nuclear complex of the diagonal band, and the cortical amygdala. The proper tubercule and the rostrolateral tubercular seam differed from each other with regard to their immunoreactivity to calbindin and calretinin, as well as their afferents from the piriform cortex. Interestingly, the tubercular seam showed similar properties to the dwarf cell compartment, located immediately adjacent to the islands of Calleja. The most prominent input to the olfactory bulb (OfB) originated from the diagonal nuclear complex. This projection was ipsilateral, whereas the bulbar afferents from the hypothalamus and the mesopontine tegmentum were bilateral. The amygdala projected only sparsely to the OfB, but received a prominent bulbar projection. An exception was the nucleus of the lateral olfactory tract, which was poorly connected with the OfB. Unlike other species with an accessory OfB, the projections from the tenrec's main OfB did not show a topographic organization upon the lateral and medial olfactory amygdala. However, there was an accessory amygdala, which could be differentiated from the lateral nuclei by its intense reaction to NADPh-diaphorase. This reaction was poor in the diagonal nuclear complex as in monkey but unlike in rat. The variability of cell populations and olfactory bulb connections shown here may help to clarify both phylogenetic relationships and the significance of individual basal telencephalic subdivisions., (Copyright 2000 Wiley-Liss, Inc.)

The Madagascan lesser hedgehog tenrec (Echinops telfairi) is a terrestrial, nocturnal insectivore with a low encephalization index and a huge olfactory bulb. To gain insight into the organization and evolution of olfactory regions in placental mammals, the cytoarchitecture (Nissl), neurochemical attributes [zinc and acetylcholinesterase stain, nicotinamide adenine dinucleotide phosphate (NADPh)-diaphorase, and calcium-binding proteins], and interconnections (injections of wheat germ agglutinin-horseradish peroxidase and biotinylated dextran amine) of tenrec bulbar and retrobulbar regions were examined. The tenrec has a well-laminated main olfactory bulb, and modified (atypical) glomeruli are found that, to date, have been demonstrated only in murine rodents. Compared with the main olfactory bulb, the accessory bulb is relatively small, with clearly different staining characteristics, particularly with respect to NADPh-diaphorase, anticalbindin, and anticalretinin. External and central anterior olfactory nuclei also show characteristic cytoarchitectural and chemoarchitectural features. The medial olfactory peduncle seems to differ considerably from that in rodents. A small taenial structure can be separated from the hippocampal continuation. This taenia tecti presumably corresponds to the superior part of the tenia tecti in rodents, but no homologue of the rodent's prominent inferior taenia tecti could be found. The connections of bulbar and retrobulbar regions are similar to those seen in other mammals. Interbulbar projection systems connect the two olfactory bulbs through an external (topographic) and central (nontopographic) anterior nucleus; however, the topographic arrangement of the intrabulbar association system seems to differ from that seen in rodents. A reciprocity of direct olfactory bulb connections with the frontal (sulcal/orbital) cortex was found in the tenrec that has not been reported so far in other species., (Copyright 2000 Wiley-Liss, Inc.)

Hedgehogs are becoming increasingly popular as pets. This article provides a broad overview of those factors with which practitioners must be familiar to provide guidance to hedgehog owners. The taxonomy, anatomy, and natural history of the common pet species are presented along with commonly observed behaviors. Information on the reproduction and neonatal management is described. Current recommendations for handling, housing, and feeding these animals are also discussed.

We studied the absorbing peripheral lymphatic vessel with the light microscope, the transmission electron microscope, the scanning electron microscope, and three-dimensional models of the diaphragm of several rodents and insectivores under normal and experimental conditions (lymphatic stasis and dehydration). To clarify the delicate and complex mechanism that permits drainage of the abdominal cavity contents into the lymphatic circulatory system, we introduced Polystyrene latex spherules, China ink, and Trypan blue into the abdominal cavities. After anatomical comparisons of the superficial and deep networks of absorbing peripheral lymphatic vessels at the tendinous and muscular portions of the diaphragm and after classification of lymphatic vessels into absorbing and conducting functions, we examined the stomata, which, owing to morphologic and topographic findings, we defined as stable structures. Furthermore, we observed that the stomata and submesothelial connective channel are fundamental elements that facilitate the flow of the corpuscular and liquid contents of the peritoneal cavity to the submesothelial absorbing lymphatic vessel wall. Also, we underlined that the genesis of the connective channel depends on the secondary cytoplasm extensions of two distinct adjacent endothelial cells, which, to facilitate the flow of the absorbed abdominal contents, completely coat this channel. Additionally, our observations illustrate that the secondary cytoplasm extensions do not engage in continuous relationships with the basal lamina of the mesothelium and with the margins of the stoma, and, hence, the hypothesis of "lymphatic stomata" as an expression of the anchoring of the borders of the open interendothelial junctions to the orifice margins of the stoma cannot be confirmed. Moreover, we describe the presence and formation of intraendothelial channels in the lymphatic endothelial wall. We affirm that this morphological entity is a dynamic unit, because its numerical density varies according to different physiological and experimental conditions to degrees of hydrostatic and colloidal osmotic pressure and, perhaps, also to the particular characteristics of the substances that the connective channel liberates into the endothelial wall of the lymphatic vessel. In conclusion, we affirm that the absorbing peripheral lymphatic vessels of the diaphragm, by way of intraendothelial channel formations, membrane diffusion, and the vesicular path of the endothelial cells, constitute the fundamental draining elements for the corpuscular and liquid contents of the abdominal cavity., (Copyright 1999 Academic Press.)

The objective of the present study was the identification and characterization of the trigemino-diencephalic target areas in the Madagascan lesser hedgehog tenrec in order to get a more comprehensive view on the mammalian somatosensory thalamus, its evolution and representation in different species. Such an analysis has been considered important because in lower mammals the head and face are relatively well represented, but their ascending trigeminal projections have scarcely been analysed. Following injections of different tracer substances into the rostral and caudal portions of the trigeminal nuclear complex the most prominent area of termination was found in the medial ventroposterior nucleus. These projections were patchy and scarcely overlapped the region previously shown to receive spinal and dorsal column nuclear afferents. On the basis of the laterality and the intensity of the projections, two subdivisions were distinguished, the principal portion and the accessory portion receiving a dense contralateral and a weak bilateral input, respectively. They were considered equivalents to the magnocellular and parvocellular subdivisions of the medial ventroposterior nucleus in more differentiated mammals. In the latter species, however, the overlap between trigeminal and parabrachial fibres appears less extensive than in the tenrec. In addition, a weak bilateral projection was shown from the caudal trigeminal nucleus to the caudal and dorsal subdivision of the nucleus submedius. There was little, if any evidence for a trigeminal projection to the intralaminar nuclei and we failed to identify a correlate to the posterior nuclear complex of higher mammals. On the other hand, there was a distinct contralateral projection to the ventral portion of the zona incerta. This projection was of similar strength as the projection to the medial ventroposterior nucleus; it supports the notion that the zona incerta may play a crucial role in relaying trigeminal information.

The trigemino-tectal projections were investigated with anterograde and retrograde tracing techniques in the Madagascan lesser hedgehog tenrec, Echinops telfairi. There were prominent contralateral projections to the inferior colliculus (CoI) and the superior colliculus (CoS), each showing its own characteristic pattern of terminations. While the projections to the CoI were confined consistently to a circumscribed region in its ventrolateral, external portion, the projections from particularly the rostral trigeminal subdivision to the CoS were distributed inhomogenously across almost the entire rostro-caudal and mediolateral extents. Comparing these data with the spino-tectal projections published previously, it demonstrates that the somatotopic organization of ascending tectal afferents is more distinct in the CoI than in the CoS. There were roughly twice as many trigeminal neurones projecting to the CoS than to the CoI. This difference might be due to the fact that the cells projecting to CoS were distributed extensively across the trigeminal nuclear complex (peak densities in the principal and interpolar subdivisions), while the neurones projecting to the CoI were largely confined to the interpolar and caudal trigeminal subdivisions. The latter cells were located adjacent to the spinal trigeminal tract; the neurones projecting to the CoS occupied preferentially the ventral trigeminal regions at rostral levels, while from the interpolar subdivision caudalward the labelled cells shifted dorsolaterally. In comparison to other mammals the trigeminal projection to the tenrec's CoI is unique. There is evidence for such a projection in other species too, but it is poorly documented, presumably due to technical reasons.

In mammals with a well-differentiated neocortex apical dendrites of pyramidal cells form vertical bundles. Little is known about the presence of dendrite bundles in animals with a poorly differentiated cortex. In this paper the presence of dendrite bundles has been investigated in the lesser hedgehog tenrec, Echinops telfairi, a basal insectivore with a very low degree of neocorticalization. In a further step the arrangement of dendrites has been analyzed in the cerebral cortex of the red-eared pond turtle, Pseudemys scripta elegans. Among non-mammalian vertebrates, reptiles have a cerebral cortex that is relatively most comparable with the mammalian one, and the cerebral cortex of turtles shows more structural and functional similarities with the cortex in mammals than those of other reptiles. In the hedgehog tenrec, bundles of apical dendrites are found in all neo-cortical areas, the cingulate and retrosplenial cortices. The shape and arrangement of dendrite bundles are primarily determined by apical dendrites of lamina V pyramids. Apical dendrites originating in laminae III/IV or VI join these bundles, and do not give rise to separate sets of bundles in the supra- and infragranular layers as in other mammals. Center to center distances between bundles determined in the neocortical areas A(2-4) range from 7 to 76 microm, with an average of 32 microm. Area-specific differences are found concerning the length of bundles as well as the number, caliber, branching pattern and packing density of dendrites sharing an individual bundle. In the three-layered entorhinal cortex and the hippocampus dendrite bundles are not observed. In the turtle, no vertical bundles of dendrites are seen either in the medial, dorsomedial or medial part of the dorsal cortex. Only in the lateral part of the dorsal cortex are isolated bundles of apical dendrites originating from groups of perikarya situated below the main level of lamina II detected. Our findings suggest that the presence of dendrite bundles is closely related with the multilayered nature of the mammalian neocortex.

Various tracer substances were injected into the spinal cord, the dorsal column nuclei, the trigeminal nuclear complex and the somatosensory cortex in Madagascan hedgehog tenrecs. With the exception of the cases injected exclusively into the spinal cord all injections gave rise to sparse, but distinct anterograde projections to the cochlear nuclear complex, particularly the granular cell domain within and outside of the dorsal cochlear nucleus. Among these cochlear afferents the projection from the primary somatosensory cortex is the most remarkable because the hedgehog tenrec has one of the lowest encephalisation indices among mammals and a similar cortico-cochlear connection has not been demonstrated so far in other species.

Natural blindness and a subterranean, digging mode of life demand peculiar adaptations of the central nervous system in the mole rat Spalax ehrenbergi, which are the focus of this quantitative investigation. Volumes of 25 brain structures in Spalax were evaluated allometrically, using the least encephalized mammalian species, the Madagassian hedgehog-like tenrecs (Tenrecinae) as a reference base, and their sizes compared with those of the rat (as a more generalized representative of rodents) and of some subterranean Insectivora. The allometric approach reveals that Spalax has a larger brain than tenrecs and the rat. Within the brain, the neocortex and diencephalon are well developed, an observation also made in other mammalian species with a relatively high encephalization. An unique feature in Spalax is the enlargement of motor structures of the brain, such as the cerebellum (and cerebellar nuclei), and the striatum. Most conspicuous is the large size of the nucleus motorius nervi trigemini, reflecting the importance of masticatory muscles for the special digging technique, which demand an intense use of the teeth for loosening the soil.

Studies were carried out on series of paraffin scraps stained by Nissl and Klüver-Barrera methods. Habenular complex in hedgehog divides into nucleus habenularis medialis (hm) and lateralis (hl). These centers are located between anterior edge of commissura posterior and about 180 microns in front of posterior edge of corpus callosum. Length of hm is about 2.75 mm. The medial habenular nucleus is compact, well formed and outlined group of heavily stained mainly round cells. It has diveresely placed a drop-like shape, for long distance. On the dorsal side of hm there are a small more intensively stained neurons that vary from the remaining ones. The lateral habenular nucleus is shorter and less demarcated than hm. On the cross-sections, area of hlisat least twice larger than hm but its cells are very dispersed among strong myelinated fibers This nucleus most often has the shape of vertical or oblique band of neurons that generally are larger, paler stained and heteromorphic.

Using different tracer substances the pathways connecting the superior colliculus with the diencephalon were studied in the Madagascan hedgehog tenrec (Echinops telfairi), a nocturnal insectivore with tiny eyes, a small and little differentiated superior colliculus and a visual cortex with no obvious fourth granular layer. The most prominent tecto-thalamic projection terminated in the ipsilateral dorsal lateral geniculate nucleus. The entire region receiving contralateral retinal afferents was labeled with variable density. In addition, there was a widespread, homogeneously distributed collicular input to the lateralis posterior-pulvinar complex and a distinct tectal projection to the suprageniculate nucleus. The latter projections were bilateral with a clear ipsilateral predominance. Among the intra- and paralaminar nuclei the centralis lateralis complex was most heavily labeled on both sides, followed by the nucleus centralis medialis. The paralamellar portion of the nucleus medialis dorsalis and the nucleus parafascicularis received sparse projections. A clear projection to the nucleus ventralis medialis could not be demonstrated but its presence was not entirely excluded either. There were also projections to medial thalamic nuclei, particularly the reuniens complex and the nucleus paraventricularis thalami. The main tecto-subthalamic target regions were the zona incerta, the dorsal hypothalamus and distinct subdivisons of the ventral lateral geniculate nucleus. These regions also gave rise to projections to the superior colliculus, as did the intergeniculate leaflet. The pathways oriented toward the visual or frontal cortex and the projections possibly involved in limbic and circadian mechanisms were compared with the connectivity patterns reported in mammals with more differentiated brains. Particular attention was given to the tenrec's prominent tecto-geniculate projection, the presumed W- or K-pathway directed toward the supragranular layers.

Immunocytochemistry with antisera against serotonin (5-HT), dopamine (DA) and noradrenaline (NA) was used to detect monoaminergic (MA) fibres in the ventricular system of the hedgehog Erinaceus europaeus. Light microscopic examination of immunocytochemically stained sections revealed that the ventricular system of the hedgehog is unique among mammals in that the choroid plexuses receive CA axons and that the supraependyma and subependyma of the cerebral ventricles and the spinal central canal are innervated both by serotoninergic and catecholaminergic (CA) fibres. Supraependymal 5-HT axons were generally more abundant and created at places a large number of interconnected basket-like structures, whereas CA fibres were usually directed towards the ventricular lumen. In the lateral ventricles, CA fibres were more numerous in the ependyma lining grey matter, whereas a higher 5-HT innervation density was observed in the area between the corpus callosum and the caudate nucleus or the septum. In the 3rd ventricle, the ependyma of its dorsal part exhibited a higher 5-HT and NA innervation density, whereas DA fibres were preferentially distributed in the ventral half of the basal region. The ependyma lining the cerebral aqueduct displayed a higher MA innervation density in its ventral part. The ependymal wall of the 4th ventricle exhibited an extremely dense 5-HT innervation, mainly in the floor of the ventricle, relatively fewer NA fibres and only sparse DA ones. Few NA and relatively more 5-HT fibres were detected in the ependyma of the central canal. Finally, the circumventricular organs were unevenly innervated by the 3 types of MA fibres. The extensive monoaminergic innervation of the hedgehog ventricular system described here probably reflects a transitory evolutionary stage in the phylogeny of the MA systems with presently unknown functional implications.

Retrograde tracer substances were injected into either the inferior or the superior colliculus in the Madagascan hedgehog tenrec, Echinops telfairi (Insectivora), to reveal the laminar and regional distribution of corticotectal cells and to correlate the labeled areas with architectural data. The tenrecs, taken from our breeding colony, have one of the least differentiated cerebral cortices among mammals, and experimental investigations of such brains are important for the understanding of the evolution and intrinsic organization of the more highly differentiated cerebral cortex in other placental mammals. Following injections into the inferior colliculus, cortical neurons were labeled bilaterally, with an ipsilateral predominance. Most labeled cells were found in the caudolateral hemisphere, area 4 as defined by Rehkämper (1981); some were in the somatosensorimotor cortex, as defined in a previous study. The labeled neurons in area 4 were located in layers V and VI, forming two bands of cells separated from each other by a poorly labeled interspace. A further subdivision of this presumed auditory region could not be achieved. This entire area was also weakly labeled following tracer injections into the superior colliculus. The labeled cells, however, were restricted to layer V of the ipsilateral side. The most consistent sites of labeled cells following injections into the superior colliculus were found in layer V of the ipsilateral caudomedial hemisphere, Rehkämper's caudal area 3, and the transitional zone adjacent to the retrosplenial cortex. This area is small in comparison to the entire region that was found in this study to project to the superior colliculus. The superior colliculus also receives projections from the ipsilateral sensorimotor and cingulate cortices. The latter projections are particularly striking in comparison to other mammals because they originate from along the entire rostrocaudal extent of the cingulate/retrosplenial region.

The adult erinaceous hedgehog, unlike other mammals, has recently been shown to have prominent crossed projections from the thalamus to the motor cortex. There are suggestions relating this unique pattern of connectivity to the overall degree of brain differentiation and/or the poorly developed corpus callosum. The present tracing study demonstrates that the Madagascan lesser hedgehog tenrec, with its tiny corpus callosum and one of the lowest neocorticalization indices among insectivores, has extensive crossed cortico-thalamic projections, but essentially the same sparse thalamic projections to the contralateral cortex as have placental mammals with more differentiated brains. The implications of the findings and the relevance of extracallosal pathways are discussed.

High affinity melatonin-binding sites have been described, by means of autoradiography with 2-125I-melatonin as the ligand, in more than 60 brain areas of about 20 mammalian species, with dramatic variations in the nature and number of labelled structures among the different species studied. As melatonin is involved in the synchronization of biological rhythms, we have tried to correlate the brain areas containing melatonin-binding sites with some rhythmic functions typical of given species. Therefore, we have studied the location of melatonin-binding sites in the complete brain of five long-day breeders with hibernation cycles, viz. one insectivore and four rodents. With the exception of the suprachiasmatic nuclei and the pars tuberalis of the pituitary, both of which contain binding sites in all five species, few reactive structures are common, even among species from the same family, e.g. the edible dormouse and the garden dormouse.

In order first to overcome the difficulties in understanding the increasing amount of information available regarding the mammalian somatosensory thalamus, and then to correlate the findings among different species and integrate them into a general concept of thalamic organization, the present study investigated the spinothalamic and medial lemniscal projections in Madagascan hedgehog tenrecs (Echinops telfairi and Setifer setosus). Tracer substances were injected into the dorsal column nuclei and into spinal segments at various levels; additional injections were made into the inferior colliculus. The ascending somesthetic projections were to predominantly contralateral posterolateral target areas, and were almost mirror-like on both sides to intralaminar and medial thalamic nuclei. The densest and most extensive projections, originating mainly from the high cervical spinal cord and the dorsal column nuclei, reached the posterolateral thalamus caudal to the lateral geniculate nucleus. This region was difficult to subdivide cytoarchitecturally; nevertheless, on the basis of its labeling pattern, several subdivisions could be described and preliminary named. Some of them compared tentatively with the internal portion of the medial geniculate nucleus (GM) and the ventral posterior nuclear complex (VPC) in more differentiated mammals. The most prominent subdivision, however, located subjacent to the lateral surface of the brainstem, was shown to receive additional fibers from the inferior colliculus. This region might be considered a further subdivision of GM, VPC, a perigeniculate area, and/or a region of its own not comparable at present, with thalamic regions in other mammals. On the other hand, it may also be a remnant of the hypothetical, diffuse multimodal region from which GM and VPC have possibly evolved.(ABSTRACT TRUNCATED AT 250 WORDS)

The distribution of serotonin (5-HT) immunoreactive fibers in the ventricular system of the hedgehog Erinaceus europaeus was studied by means of specific antibodies against serotonin. Light microscopic examination of immunocytochemically stained coronal sections showed abundant serotoninergic fibers, unevenly distributed along the ventricular wall, both supraependymally and subependymally. No immunoreactivity was evident in the choroid plexus. Serotonin fibers lying supraependymally exhibited distinct morphological and distributional features. They were either found to terminate freely in the ventricular lumen or contributed to the formation of a large number of interconnected basket-like formations, particularly abundant in the lateral and fourth ventricles, where they usually lay opposite to the choroid plexus. In the electron microscopic study of the 5-HT-stained thin sections, the ependymal monolayer was found to be composed of squamous or cuboidal cells protruding into the ventricle. Immunoreactive axons cut in favorable tangential planes formed typical baskets that encircled the apical cytoplasmic process of the ependymal cells. Immunoreactive varicosities containing clear and dense cored vesicles were found either to terminate as "free arborizations" within the ventricles, or contacted the ventricular surface of ependymal cells. In these contacts, junctional specializations resembling those of classical synapses were often observed. The functional significance of the 5-HT baskets which surround individual ependymal cells is briefly discussed.

The biology, physiology, husbandry, and handling of the hedgehog are described. Diseases and conditions of practical significance are reviewed.

Adult male short-tailed shrews, Blarina brevicauda, (Insectivora: Soricidae) were trapped in Virginia and Pennsylvania, anesthetized, and perfused via the left ventricle of the heart with fixative. The submandibular glands were dissected free and prepared for transmission electron microscopy. The lobular, compound tubuloacinar glands had secretory endpieces consisting of seromucous acini and serous tubules connected to intercalated ducts, granular ducts, striated ducts, and excretory ducts. The general cytology of the submandibular gland of Blarina shared morphological characters with individuals in several other mammalian orders and yet differed in many ways from another Insectivore, the European hedgehog, Erinaceus europaeus.

The terminal distributions of spinal and dorsal column nuclear projections to tectum, pretectum, and central gray of hedgehog tenrecs (Echinops telfairi and Setifer setosus) were investigated using anterograde axonal flow and various tracer substances. In the inferior colliculus, the densest and most extensive mesencephalic projections were found within the pericentral regions. One target area, referred to as the external portion of the inferior colliculus, was represented as a semicircle of grain patches lateral and caudal to the central nucleus. This region received somesthetic afferents from the dorsal column nuclei and from spinal segments at various levels. In contrast, after high cervical injections, the pericentral portion dorsomedial to the rostral half of the central nucleus was labeled almost exclusively. This area of labeling was distinct from the labeling in the central gray and might be best compared with the intercollicular zone in other species. The superior colliculus received projections predominantly from the high cervical cord; minor projections also arose from lumbar spinal segments and the dorsal column nuclei. The terminal field covered roughly the caudal half of the colliculus and involved the stratum griseum intermediale in a patch-like fashion. Some labeling was also found in the stratum griseum profundum and in the stratum griseum superficiale. Other than in the colliculi, weak pretectal projections were observed following dorsal column nuclear injections, while the nucleus of Darkschewitsch was labeled best following lumbosacral injections. All mesencephalic target areas were labeled consistently on the contralateral side, while their ipsilateral side was involved to a varying degree: The relatively most prominent ipsilateral labeling was seen in the central gray, being roughly similar on both sides; scarcely any labeling was noted in the ipsilateral superior colliculus. Tectal injections of retrograde tracer, in addition, revealed a considerable number of labeled neurons in a relatively cell-poor region immediately ventral to the high cervical dorsal horn. This region might correspond to the lateral cervical nucleus, an aggregation of neurons that so far has only been demonstrated in higher mammals.

The distribution of the neuropeptide Y (NPY) was studied in geniculate and peri-chiasmatic regions in the lesser hedgehog-tenrec, Echinops telfairi (Insectivora). Only few neurons demonstrated NPY-like immunoreactivity in the ventral lateral geniculate nucleus. In contrast, NPY-immunoreactive perikarya were clearly present in the suprachiasmatic nucleus (SCh) and dorsal and caudal to it. The latter region might correspond to the subparaventricular zone (SPV), recently identified in the rat as an additional area involved in processing circadian rhythms. While the distribution of a distinct cell population across nuclear boundries in both SCh and SPV might conform to the present idea of processing circadian rhythms, the presence of NPY-like immunoreactive neurons in these areas is rather unusual. In mammals, such neurons have only been demonstrated so far in the mentioned insectivore as well as in man.

The cytoarchitecture of the claustrum in the hedgehog (Erinaceus europaeus) brain, the morphology of its neurons, and the efferent connections with cortical and subcortical structures were studied with the Nissl and Klüver-Barrera, the Golgi, and the horseradish peroxidase methods. It was found that the claustrum is a well developed nucleus in the hedgehog telencephalon and, as in other mammals, is divided into dorsal and ventral parts. In Golgi-stained sections, spiny multipolar cells are the predominant neurons of both the dorsal and the ventral claustrum and are projection neurons. Aspiny multipolar neurons with fewer, often beaded, dendrites constitute a minority in both divisions and are interneurons. Injections of wheat germ agglutinin-horseradish peroxidase (WGA-HRP) in the prefrontal, motor, somatosensory, auditory and visual areas, and HRP or WGA-HRP injections in the thalamus showed that: (1) the claustroneocortical projections originate in the dorsal claustrum and are distributed to the entire neocortex; these projections are mainly ipsilateral but some also originate contralaterally; (2) the claustroneocortical projections show a rough topographic organization; there exists a substantial degree of overlap; and (3) the claustrothalamic projection, arising throughout the dorsal claustrum, is strictly ipsilateral. No evidence of a thalamoclaustral projection was found. The present results suggest that, although the hedgehog has been referred to as a "paleocortical mammal" owing to the great development of its rhinencephalic structures in comparison with its small neocortex, the dorsal claustrum is well developed and is connected with all neocortical areas as well as with the thalamus, establishing it as a key structure in the hedgehog forebrain.