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Heteropterans communicate chemically through thoracic or abdominal glandular complexes. The dorso-abdominal scent glands (DAGs) are externalized by cuticular specialized structures forming the external scent efferent system (SES). Different groups in Heteroptera present other glands, such as the Asopinae (Pentatomidae), whose males can have ventral abdominal pheromonal glands externalized by cuticular modifications, called glandular patches (GPs). Here we describe the SES of DAGs and, for the first time, the GPs of 22 Asopinae genera. The ostioles of SES 1 vary in shape. SES 2 and SES 3 were restricted to scars, indicating that only the SES 1 remains functional in adults. The GPs are found mostly in segments V and VI. We have not found any difference in the morphological pattern between the SES of species bearing GPs and those lacking it, meaning that the acquisition of GPs is likely related to some sexual behavior, thus not as a complex structure replacing any role of the DAGs. The cuticle of the GPs is microsculptured, bearing many pores surrounding the base of sensilla being the pathway for the secretions to reach the outside of the exoskeleton. The sensilla may be adaptations to increase the contact surface, assisting rapid evaporation of the volatile secretions from the pores., (Copyright © 2020 Elsevier Ltd. All rights reserved.)

We describe the morphology of alar androconia and the female abdominal scent gland of Heliconius erato phyllis, Heliconius ethilla narcaea, and Heliconius besckei. Androconial scales of Heliconius, which are arranged in overlapping wing bands, release pheromones during courtship, probably through vibratory movements of male wings over the female to induce her to mate. An antiaphrodisiac is produced by glands located in the valves of the male and is transferred during copulation to the yellow dorsal abdominal sac present in the virgin female, causing this sac to emit a scent that reduces the attractiveness of the female for courtship with other males. Stereomicroscopy, SEM, and TEM analyses were conducted to describe the morphology of the internal and external scales and the external abdominal scent sac. The findings revealed different sizes of external androconial scales and an internal group of porous structural vesicles that are probably related to the preservation of internal space, reception and storage of secretions, and elimination of volatiles when the male is actively involved in courtship. Translucent projections on the female abdominal scent sac create open reservoirs for the reception, storage, and emission of antiaphrodisiac volatiles along with stink clubs. Male valve denticles vary in form and probably attach securely to the female sac during mating, thus ensuring secretion transfer. These features are discussed in the context of a comparative analysis., (© 2020 Wiley Periodicals, Inc.)

The ozopores of cosmetid harvestmen rest upon lateral projections of the carapace, have simple or highly reduced channels, and are partially obscured by enlarged dorsal processes associated with coxae I and II. Rather than use scent gland secretions to form a chemical shield on the dorsum, the cosmetid harvestman exhibits a unique defensive behavior known as "leg dabbing" in which the distal tip of tarsus I or II is dipped into fluid that accumulate at the base of coxa II and the droplet on the tarsus is pointed toward the predator. Relatively little is known about interspecific variation in ozopore morphology among cosmetid harvestmen. In this study, we used scanning electron microscopy to examine the ozopores of males and females of nine species as well as those of antepenultimate nymphs for two species. Among adults, we found differences between species in the shapes of the ozopores (round or subtriangular), the morphology of the dorsal and lateral channels (if present), and the relative size, shape and armature of the dorsal posterior process (dpp) of coxa I and the dorsal anterior process (dap) of coxa II. Our observations suggest that the morphology of dpp I and dap II could be sources for systematic characters in future phylogenetic studies of the Cosmetidae. We observed ontogenetic differences but relatively little intersexual variation in the morphology of the ozopore. The ozopores of nymphs are generally more oval than those of adults and the opening of the ozopore of the nymph is less obstructed, if at all, by the dorsal coxal processes of legs I-II. These morphological differences suggest that nymphs may use scent gland secretions in a manner different from that of adults., (© 2019 Wiley Periodicals, Inc.)

A macroscopic and microscopic study of the mandibular organ of the silky anteater (Cyclopes didactylus) was carried out. The organ extends from below the zygomatic bone line to the middle of the mandible body, between the skin and the masseter muscle, on both sides of the animal. It has an average length of 11.7 mm and a width of 6.3 mm. In the mesoscopic analysis, it was observed that the organ presents in yellowish color due to the high amount of sebaceous content. In the histological analysis, the mandibular organ was observed to be composed of innumerable alveoli of the specialized sebaceous gland, surrounded by a layer of adventitia tunica. Scanning electron microscopy (SEM), revealed an apparent alveolar division with what appeared to be a sulcus at its center. The information here presented regarding the constitution and location of this structure has not been previously explored for other species and differs with respect to other descriptions for anteaters. Based on the present study, it is suggested that the mandibular organ is involved in social interaction in this species., (© 2019 Wiley Periodicals, Inc.)

The internal and external anatomy of the posterior metathoracic region, pregenital abdomen, and associated nervous system of the heteropteran infraorder Enicocephalomorpha are thoroughly described, using an array of state-of-the art techniques. Based on morphology, it is hypothesised which modes of communication these insects use. This study is based primarily on an undescribed species of Cocles Bergroth, 1905 (Enicocephalidae) and another undescribed species of Lomagostus Villiers, 1958 (Aenictopecheidae), but additional representatives of the infraorder are also examined. Our results are compared with the literature on other Heteroptera. The metathoracic scent gland system of Enicocephalomorpha uses the same muscles as that of more derived Heteroptera, although the efferent system is different. The presence of a tergal plate and well-developed longitudinal musculature in the families Enicocephalidae and Aenictopecheidae, as well as a sexually dimorphic set of sclerites and membranes that allow an as yet undetermined type of motion, may indicate the presence of vibrational signaling in the infraorder, although experimental confirmation is required. Our findings raise new research questions regarding heteropteran functional morphology and communication., (Copyright © 2017 Elsevier Ltd. All rights reserved.)

Caudal courtship glands (CCGs) are sexually dimorphic glands described in the skin of the dorsal tail base of some male salamanders in the genera Desmognathus, Eurycea, and Plethodon in the family Plethodontidae. These glands are believed to deliver pheromones to females during courtship, when the female rests her chin on the dorsal tail base during the stereotypic tail straddling walk unique to plethodontids. Although CCGs have been studied histologically, no investigations of their ultrastructure have been made. This article presents the first study on the fine structure and seasonal variation of CCGs, using the plethodontid Plethodon cinereus. The CCGs vary seasonally in height and secretory activity. The mature secretory granules observed in males collected in October and April consist of oval, biphasic granules that are eosinophilic and give positive reactions to periodic acid-Schiff for neutral carbohydrates but do not stain for acidic mucosusbtances or proteins with alcian blue and bromphenol blue, respectively. Granular glands, some of which contain mucous demilunes, are twice as large as CCGs, are syncytial (unlike CCGs), and stain for proteins. Mucous glands are similar in size to CCGs, but are basophilic, show no seasonal variation in secretory activity, and stain positive for acidic mucosubstances. CCGs do not resemble cytologically the sexually dimorphic mental glands of some plethodontids, which contain round or oval granules filled with an electron-dense amorphous substance. The CCGs are similar histologically to sexually dimorphic skin glands described in some anurans, but more comparative work is needed., (© 2014 Wiley Periodicals, Inc.)

The Heteroptera show a diversity of glands associated with the epidermis. They have multiple roles including the production of noxious scents. Here, we examine the cellular arrangement and cytoskeletal components of the scent glands of pentatomoid Heteroptera in three families, Pentatomidae (stink bugs), Tessaratomidae, and Scutelleridae (shield-backed bugs or jewel bugs). The glands are; (1) the dorsal abdominal glands, (2) the tubular glands of the composite metathoracic gland, and (3) the accessory gland component of the composite metathoracic gland. The dorsal abdominal glands are at their largest in nymphs and decrease in size in adults. The metathoracic gland is an adult-specific gland unit with a reservoir and multiple types of gland cells. The accessory gland is composed of many unicellular glands concentrated in a sinuous line across the reservoir wall. The lateral tubular gland is composed of two-cell units. The dorsal abdominal glands of nymphs are composed of three-cell units with a prominent cuticular component derived from the saccule cell sitting between the duct and receiving canal. The cuticular components that channel secretion from the microvilli of the secretory cell to the exterior differ in the three gland types. The significance of the numbers of cells comprising gland units is related to the role of cells in regenerating the cuticular components of the glands at moulting in nymphs., (Copyright © 2014 Elsevier Ltd. All rights reserved.)

The morphological structure of the metathoracic scent glands (MTGs) in Adelphocoris suturalis was observed by utilizing scanning electron microscope (SEM). Also, the secretions of MTGs in male and female were analyzed by using gas chromatography-mass spectrometry (GC-MS). The result showed that the MTGs comprised a reservoir and paired lateral glands, which are connected to a reservoir by duct. The MTGs belong to the diastomian type. A usually depressed channel extends from opening downward the middle of metathorax, a tongue-like structure was covered by bristles and mushroom-shaped cuticular structures, known as evaporative area. In GC-MS investigation, differences were found in quantitative or qualitative compositions of the substances between the two sexes. In our study, hexyl butyrate was the most abundant compound in the MTGs of A. suturalis, comprising ∼85% of total secretions in both female and male, respectively. 4-oxo-(E)-2-hexenal (5.22%) was the second most abundant compound in female MTGs secretions, whereas octacosane (2.42%) followed hexyl butyrate in male MTGs secretions., (© The Author 2014. Published by Oxford University Press on behalf of the Entomological Society of America.)

Elasmucha ferrugata (Fabricius, 1787) (Heteroptera: Acanthosomatidae) provides maternal care of eggs and larvae. Adults of both sexes have functional anterior dorsal abdominal scent glands (DAGs). Study of all internal and external cuticular structures of DAGs revealed that no DAGs are fully functional in the 1st larval instar, and very probably they are only slightly functional in the 2nd instar. Median and posterior DAGs are undoubtedly not functional in adults. There exists sexual dimorphism in the number of multicellular glandular units in anterior glands in adults. The occurrence of cuticular ductules of these units proves these to be functional glands. This is best considered in combination with the findings of a well-developed evaporatorium. Developed cuticular intima of the gland reservoir and/or the nearly closed ostiole or ostiolar scar bears no information about the functionality of the gland.

In order to elucidate the relationship between androgens and the function of the muskrat (Ondatra zibethicus) scented glands during the breeding season, we investigated immunolocalization of steroidogenic enzymes P450scc, 3βHSD and P450c17 in the muskrat testes and scented glands. Nine adult muskrats were obtained in March (n=3), May (n=3) and July (n=3) 2010. Steroidogenic enzymes were immunolocalized using polyclonal antisera raised against bovine adrenal P450scc, human placental 3βHSD and porcine testicular P450c17. Histologically, all types of spermatogenic cells including mature-phase spermatozoa in seminiferous tubules were observed in all testes. Glandular cells, interstitial cells, epithelial cells and excretory tubules were identified in scented glands during the breeding season. P450scc, 3βHSD and P450c17 were only identified in Leydig cells during the breeding season; P450scc and P450c17 were observed in glandular cells of scented glands, however, 3βHSD was not found in scented glands during the breeding season. These novel findings provide the first evidence showing that scented glands of the muskrats are capable of locally synthesizing androgens and androgens acting via an endocrine, autocrine or paracrine manner may play an important role in scented gland function during the breeding season.

The morphological organization and functional anatomy of prosomal defensive (scent) glands in Paranemastoma quadripunctatum, a representative of the dyspnoid harvestmen, was investigated by means of histological semithin sections, software-based 3D-reconstruction and scanning electron microscopy. Scent glands comprise large, hollow sacs on either side of the prosoma, each of these opening to the outside via one orifice (ozopore) immediately above coxa I. In contrast to the situation known from laniatorean, cyphophthalmid and some eupnoid Opiliones, ozopores are not exposed but hidden in a depression (atrium), formed by a dorsal integumental fold of the carapace and the dorsal parts of coxae I. Glandular sacs are connected to ozopores via a short duct which is equipped with a specific closing mechanism in its distal part: A layer of modified epidermal cells forms a kind of pad-like tissue, surrounding the duct like a valve. Several muscles attached to the anterior parts of the glandular reservoir and to the epithelial pad may be associated with ozopore-opening. The actual mechanism of secretion discharge seems to be highly unusual and may be hypothesized on the basis of corroborating data from behavioral observations, scent gland anatomy and secretion chemistry as follows: Enteric fluid is considered to be directed towards the ozopores via cuticular grooves in the surface of the coxapophyses of legs I. Then, the fluid is sucked into the anterior part of the scent gland reservoirs by the action of dorsal dilator muscles that widen the reservoir and produce a short-term negative pressure. After dilution/solution of the naphthoquinone-rich scent gland contents, a secretion-loaded fluid is thought to be discharged with the help of transversal compressor muscles. This is the first detailed study on the functional anatomy of scent glands and the mechanisms of secretion discharge in the Dyspnoi., (Copyright © 2011 Wiley-Liss, Inc.)

Morphology and ultrastructure of metathoracic scent glands (MTGs) of Graphosoma lineatum (Heteroptera, Pentatomidae) were studied by scanning electron microscopy (SEM) and transmission electron microscopy (TEM). Extracts of the volatile fraction of the MTG secretion from males and females were subjected to initial analysis. One pair of the MTG is composed of a reservoir and a pair of lateral glands connected to the reservoir with a duct. MTGs are open in between the meso- and metacoxae, on evaporation areas with a mushroom-like structure. Reservoir walls embody two types of cells, type I and type II, respectively. Cells of type I have numerous organelles, while type II cells have only been found in a certain area of the reservoir wall. They have large secretory ducts lined by a cuticular intima layer. The lateral glands connected to reservoir have two further types of cells. Lateral glands are lined by type A secretory cells and secretory duct is found in their cytoplasm. Type B cells are poor in organelles and are smaller than type A cells. Coupled gas chromatography-mass spectrometry examinations revealed that both in males and females of G. lineatum MTGs 14 chemical compounds occur, among which only 10 are common. These secretions indicate information such as defensive and pheromonal activities, other functions could be attributed to the secretion of the MTG of G. lineatum by comparison with other closely related bug species. In the analyses of MTGs of females of G. lineatum, n-octadecanoic acid was observed at the most and n-undecane was determined at lowest level, while males of G. lineatum n-tridecane was determined at the highest level; and (E)-2-hexenyl acetate has been observed at the lowest.

Many lizards have epidermal glands in the cloacal or femoral region with semiochemical function related to sexual behavior and/or territorial demarcation. Externally, these glands are recognized as a row of pores, opening individually in the center of a modified scale. In many species the pores are used as systematic characters. They form a glandular cord or, in some species, a row of glandular beads below the dermis, and are connected to the exterior through the ducts, which continuously liberate a solid secretion. Dead cells, desquamated from the secretory epithelium, constitute the secretion, known as "a secretion plug." The present work focuses on the morphology of the femoral glands of the teiid lizard Ameiva ameiva, correlating it to the way in which the secretion is deposited in the environment. The results here obtained are compared to those available for other lizards and amphisbaenians. We observed that the diameter of the glandular pores did not show significant differences between males and females. The glands comprise germinative and secretory cells, which pass through at least three stages of differentiation, during which an accumulation of cytoplasmic granules, with a glycoprotein content, occurs. The cells eventually die and desquamate from the secretory epithelium, forming a secretory plug mostly constituted by juxtaposed nonfragmented secretory cells. Because of the arrangement of the rosette-like scales surrounding the femoral pores, we suggest that when the animal is in a resting position, with its femoral regions touching the ground, these scales may be involved in the breakage of their respective plugs, depositing tiny portions on the substrate. In this manner, it seems that the method for signal dispersion in this species involves specifically adapted structures and does not simply involve the chance breakage of the plug, as the gland secretes it. Signal dispersion must also be intimately associated with the animal's movement within its territory.

The morphology and ultrastructure of the metathoracic scent glands (MTG) of Eurygaster maura were studied by scanning electron microscopy (SEM) and transmission electron microscopy (TEM). Also, extracts of the volatile fraction of the MTG secretion from males and females were analyzed by capillary gas chromatography-mass spectrometry (GC-MS). In SEM investigations, MTG are composed of a reservoir and a pair of lateral glands connected to the reservoir by a duct. MTG are open in between the meso- and the metacoxae. These areas, called evaporation areas, are composed of mushroom-like elements. In TEM investigations, the reservoir walls contained two types of cells. Generally, a reservoir is lined by a single layer of epithelial cells, type I cells, which have numerous organelles. Type II cells are found only in a certain area of the reservoir wall. These cells have large secretory ducts lined by a cuticular intima layer. The lateral glands are lined by secretory cells and a secretory duct found in their cytoplasm. Nuclei of secretory cells are closed to the basal region of the cells and circular-shaped. In GC-MS investigations, the MTG exhibited a typical scutellerid composition. In general, (E)-2-hexanal, (E)-2-hexenyl acetate, n-tridecane, n-hexanoic acid, octadecanoic acid, and n-dodecane compounds were present, while diisooctyl acetate and 14-Beta-H-Pregna were detected only in the male extracts of Eurygaster maura.

Gas chromatographic-mass spectrometric analyses of the scent gland secretions of Siro duricorius and S. exilis (Opiliones, Cyphophthalmi, Sironidae) revealed a set of 24 components, comprising a series of saturated and unsaturated methyl ketones (C11-C15) and four naphthoquinones. Whereas the scent gland secretions of S. duricorius, collected in Austria, and S. exilis from USA were qualitatively nearly indistinguishable (with the exception of acetophenone that was specific to S. duricorius), they distinctly differed in their relative quantitative compositions: major components of the secretion of S. duricorius were 7-tridecen-2-one, tridecan-2-one, undecan-2-one, 1,4-naphthoquinone, 6-methyl-1,4-naphthoquinone (tentatively identified only), and 4-chloro-1,2-naphthoquinone. In contrast, in S. exilis a compound tentatively identified as 6-methyl-4-chloro-1,2-naphthoquinone was present in large amounts (in S. duricorius a trace component), whereas undecan-2-one only occurred in minor quantities. Secretion profiles of juveniles and adults (both sexes) of each species showed high correspondence. This is the first report on the chemistry of scent gland secretions of the opilionid suborder Cyphophthalmi. 4-Chloro-1,2-naphthoquinone was identified as a new exocrine product of arthropods, whereas 1,4-naphthoquinone and the tentatively identified 6-methyl-1,4-naphthoquinone are known constituents of exocrine secretions from one species of palpatorid opilionids, Phalangium opilio. In contrast, all ketones identified were new for opilionid scent glands, although similar ketones are characteristic of scent gland secretions of palpatorid genera Leiobunum and Hadrobunus. With regard to the near-basic position of Cyphophthalmi in currently proposed phylogenetic trees of Opiliones, naphthoquinones and ketones from Siro may represent the condition ancestral to the (derived) naphthoquinone- and ketone-rich secretions in phalangid Palpatores.

In female alates of Macrotermes annandalei, two types of abdominal glands are involved in the secretion of sex pheromone. Tergal glands are found at the anterior margin of tergites 6-10 and posterior sternal glands (PSGs) are located at the anterior margin of sternites 6-7. The cytological features of both types of glands are quite similar. The fine structural organization of PSGs is studied more precisely and described for the first time. The glandular cuticle is pitted with narrow apertures corresponding to the openings of numerous subcuticular pouches. Several Class 3 glandular units open in each pouch. One canal cell and one secretory cell make an individual glandular unit. The canal cell is enlarged apically and is connected with the other canal cells to form a common pouch. Based on the structural features found in these glands, we propose a common secretory process for PSGs and tergal glands. During the physiological maturation of alates inside the nest, secretory vesicles amass in the cytoplasm of secretory cells, while large intercellular spaces collapse the cuticular pouches. At the time of dispersal flight, pouches are filled with the content of secretory vesicles while intercellular spaces are sharply reduced. After calling behavior, no secretion remains in the glands and pouches collapse again, while secretory cells are drastically reduced in size. The structure and the secretory processes of PSGs and tergal glands are compared to those of abdominal sexual glands known in termites.

This study examined the dynamics of colonization of Trypanosoma cruzi in the scent glands of the opossum Didelphis marsupialis following direct inoculation with 10(5) epimastigotes of isolate G-49 (an opossum-derived strain). One, three, and five days, 1 month, and 1 year after inoculation, scent glands were fixed for analysis using brightfield and electron microscopies. One day after inoculation the parasites, mainly as epimastigotes, were randomly distributed into the lumen. From the third day on, the parasites still in the form of epimastigotes tended to concentrate closer to the epithelium. The flagellates reached the definitive distribution pattern on the fifth day, when they formed huge clusters deep into the foveae. In samples collected 1 month and 1 year after inoculation, the ratio of epimastigotes:trypomastigotes was 1:1, with epimastigotes predominating near the epithelium and trypomastigotes far from it. Our observations suggest that T. cruzi grows continuously in the scent glands and does not depend on adhesion to promote metacyclogenesis. Metacyclogenesis far from the epithelium seems to be an important selective advantage to both host and parasite, since it assures the elimination of the infective forms of the parasite when the host expels the glands' contents, which occurs in frightening situations or at times of stress. The morphological characteristics of infected and noninfected scent glands using transmission and scanning electron microscopies were also described., (Copyright 2001 Academic Press.)

Plethodon cinereus, the red-backed salamander, is a small territorial vertebrate that defends refugia located on the forest floor. As a component of territorial defense, these animals use scent marks to advertise their refugia. Behavioral evidence indicates that scent marks are produced by the postcloacal glands located on the ventral surface of the tail just posterior to the cloaca. We placed animals on unmarked substrates and recorded changes in serous acini from the postcloacal and shoulder region over a 48-h period. Within the first hour there was an increase in the number of acini filled with secretory product in the postcloacal region. At 12 h the number of full acini decreased and the number of empty acini increased. By 24 h the number of empty acini had decreased and the number of renewing acini containing secretory cells producing product had increased. By 48 h the ratio of full to empty to renewing acini was similar to those observed at the start of the study. In the shoulder region, no significant changes in the ratio of full to empty to renewing acini were observed. Observations of the serous acini within the postcloacal region and the shoulder region indicate that the mode of secretory production is holocrine. These findings are additional evidence that the postcloacal glands are the site of scent mark production., (Copyright 1999 Wiley-Liss, Inc.)

The femoral or cloacal region of many species of lizards and amphisbaenians exhibits epidermal glands. The pores of these glands are plugged with holocrine solid secretions that serve as semiochemical sources. Many authors assume that these glands are mainly associated with reproduction and demarcation of territory. The structure of precloacal glands in Amphisbaena alba was previously studied by Antoniazzi et al. (Zoomorphology 113:199-203, 1993; J. Morphol. 221:101-109, 1994). These authors suggested that as the animal moves inside tunnels, the secretion plugs are abraded against the substrate, releasing a secretion trail. Some aspects of the plug were difficult to interpret in fine sections due to the dense and brittle nature of the plug. The morphology of the trail, and the manner of deposition on the substrate, have never been reported. This study presents a primarily scanning electron microscopic description of A. alba precloacal glands and of the secretion plugs. It also demonstrates experimentally the formation of the trail and its fine morphology. The results show that when the plugs scrape against the substrate, their constitution helps them to fragment into tiny pieces, which are spread on the ground, thus forming a trail. Each one of the fragments corresponds to a secretion granule of the precloacal gland's secretory cells. In this way, the trail might have an extensive area for volatilization of semiochemicals, constituting an efficient means of intraspecific communication inside the tunnels., (Copyright 1999 Wiley-Liss, Inc.)

The cutaneous glands of the forehead and the metatarsus were studied by histological and histochemical methods and electron microscopy in adult male and female impalas in various seasons of the year. All glandular areas consist of apocrine and holocrine glands, which, however, occur in different proportions. Our findings in the apocrine gland cells suggest (1) the synthesis and exocytosis of a glycoproteinaceous secretory product stored in secretory granules, (2) typical apocrine secretion of the transformed apical cytoplasm, and (3) transepithelial fluid transport. The Golgi apparatus and apical membrane have binding sites for several lectins (PNA, HPA, RCA I, WGA). Cytokeratins 7, 14 and 19 are expressed at various intracellular localizations, suggesting an active role in the secretory mechanisms. The glands of the male forehead show marked seasonal changes in activity that are correlated with the main phases of the reproductive cycle, with the highest cellular activity occurring during the rut in April/May. The female forehead glands are only moderately developed and do not undergo seasonal changes. The metatarsal glands are of equal size in males and females and show no seasonal changes in activity. This study supports the hypothesis that (1) forehead glands in the male have a signaling role in the rut and (2) the metatarsal glands have a more general, probably social role maintaining and restoring contact between herd members.

Morphological and ultrastructural features of the paracloacal glands of Metachirus nudicaudatus are described. Two pairs of glands, one on the right and the other on the left of the anal canal, are formed, each consisting of a major and a minor portion. Their wall is made up of three layers: a mucosal, a muscular and an external capsule. The inner one is a mucosa the epithelium of which contains holocrine cells characterized by lipid droplets and intermediate filaments. The surrounding vascular lamina propria contains flattened tubular apocrine glands whose epithelial cells contain abundant endoplasmic reticulum, prominent Golgi complexes and numerous secretory granules. The middle layer is formed by skeletal striated muscle and the outer (third layer) consists of dense connective tissue. Each gland originates from a single duct. Transverse sections show that each duct, except in the female major gland, is in fact formed by a duct system. One of these ducts comes from the central cavity, lined by holocrine epithelium, and the others result from the branched tubular glands of the lamina propria.

The presence of the scent glands were examined macroscopically and histologically in the Japanese vole, Microtus montebelli and the Hungarian vole, Microtus arvalis. A pair of scent glands were observed on the buttocks of the Japanese vole as the oval nodules with yellowish colored skin. The size of the glands was larger in males than in females. Histologically, the glands were composed of the aggregation of many acini of sebaceous glands. The epidermis above the scent glands were thicker than that in the other areas. In the Hungarian vole, no such gland could be detected with macroscopical and histological examinations.

In vivo autoradiography with [3H]1,25-dihydroxycholecalciferol (vitamin D, soltriol) and immunostaining with antibodies to vitamin D receptor were applied to identify specific binding sites in the abdominal scent gland of male Siberian hamster (Phodopus sungorus). Nuclear concentration of radiolabeled hormone and receptor antibodies was observed in the corresponding cell types including basal cells of sebaceous glands, cells of the outer hair sheaths and hair bulbs, and also keratinocytes in the epidermis. Cells of the hair dermal papillae and fibroblasts of the dermis did not show nuclear labeling. There was good correspondence between the autoradiographic and immunohistochemical data. The results indicate the presence of receptors for vitamin D-soltriol and suggest a seasonal regulation of scent gland marking activities by this steroid hormone of sunlight in cooperation with the sex steroid testosterone.

Male and female in bred Mongolian gerbils aged 4, 5, 10, and 20 weeks were examined for the presence of a ventral scent gland macroscopically and histologically. It was found in about half of the gerbils aged 4 weeks and in all of the gerbils aged over 5 weeks. In adult male gerbils it weighed three times as much as in females. The ventral scent gland exhibited a sebaceous-like structure which consists of giant glandular cells with small vacuoles in the cytoplasm and the glandular cells displayed eosinophilic bodies contained within a duct, which are extruded through the lumen as holocrine-type secretion.

The monoptychic 'apocrine' scent glands of the sternal region of two adult male Tupaia belangeri were studied by transmission and scanning electron microscopy, in order to assess the modes of release of their secretory products. In segments of the secretory tubules with a narrow lumen the epithelial cells are columnar and are firmly connected to each other by desmosomes and junctional complexes. Myoepithelial cells are interspersed between the secretory epithelium and the basement membrane. The cytoplasm of the secretory epithelial cells contains granular and agranular endoplasmic reticulum, mitochondria, Golgi apparatus, lysosomes and secretory granules. The free surface of the secretory epithelium is furnished with densely arranged microvilli. The apices of the cells protrude as dome-shaped extensions into the glandular lumen. At the tip of these extensions cellular processes of irregular shape are found. The surface of these processes shows no microvilli. They contain densely packed and dilated cisternae of agranular endoplasmic reticulum and free ribosomes. The constriction of the base of these processes and the occasional observation of a 'demarcation membrane' between a process and the secretory cell indicate that these secretory processes become detached from the secretory cells according to the apocrine mode of extrusion. Within the glandular lumen they break down and form secretion. Parallel to this apocrine extrusion the same cells produce secretory granules, the diameter of which measures 300-900 nm. The contents of these granules are released into the glandular lumen by exocytosis according to the eccrine mode of secretion. This resembles the situation in other mammals in which monoptychic glands release their secretory products by means of both apocrine and eccrine extrusion. Therefore monoptychic skin glands should not be classified into apocrine and eccrine glands. Our results corroborate Schaffer's (1927, 1940) more general classification of exocrine glands according to the nature of the secretory epithelium into monoptychic and polyptychic glands.

The abdominal scent apparatus of male Caligo eurilochus was examined at different ages by light, scanning and transmission electron microscopy. The glandular epithelium is covered with specialized scales and forms a pad on each side of the 4th to 6th abdominal segments. The pads are surrounded by smooth, elastic cuticle and can protrude toward the opposite hind wing hair pencil. The scales have a poreless cuticle with a fibrillar texture. They are impregnated by an oily, slowly volatile substance. The scales are elongated toward the base, forming hoods over the long cone-shaped sockets. The scale pedicel is anchored tension-free by rootlets in the central socket base. The slightly asymmetric cuticular sockets are very elastic, due to their high water content. They are stabilized by internal epicuticular rods. The release of the secretions from the cell and a possibly active microvillar transport is discussed. Different secretions are found in the space between the microvillar surface of the gland cell and the socket floor. They are probably discharged from the supraglandular space into the scale lumen by means of pressure and bending of the sockets. A flowback might be prevented by capillary effect of a "ball" of vesicles, which lies exactly above the outlet of the scale pedicel.

The foveal glands of Dermacentor variabilis appear to consist of 2 cell types. The outer cells (Type I) are active, with large areas of abundant finely granular material, apparently precursors of the mature secretory granules. The inner cells (Type II) are apparently storage cells. They are highly vacuolated and contain coarsely granular material as well as presumably mature secretory granules. The foveal glands of D. andersoni contain only Type II cells with extensive accumulations of presumably mature secretory granules.

Frogs of the Pleurodema thaul species have a pair of prominent elevated cutaneous glands dorsolaterally, just posterior to the sacrum, which are named lumbar glands. We have studied histologically these glands and found that their chromatophores are disposed mainly immediately under the epidermis structuring a dermal chromatophore unit. Similar to the other anuran macroglands, the lumbar glands are constituted basically by granular alveoli filled with secretion. The presence of these granular alveoli and the typical distribution of the dermal chromatophores to suggest a defensive role for the lumbar glands. In most of the amphibians granular alveoli contain secretions with toxicity for several vertebrates. On the other hand, chromatophores in this frog species, probably play an aposematic function, since their disposition on the skin permits that the lumbar glands might be taken for eyes, probably giving to an eventual predator the impression that it may be an animal of higher dimensions.

The scent gland tumor of the Syrian hamster is induced by exogenous androgen and estrogen. Microscopic nodules are induced normally in old males by endogenous androgen. The histogenesis of the scent gland tumor is complex and not completely understood. In this study microscopic preneoplastic nodules and macroscopic tumors were studied by light and electron microscopy, and the macroscopic tumors were grown in tissue culture on collagen-coated coverslips and on sponge foam matrices by the organ culture method. The cultures were fed with an unfiltered fetal calf serum-bovine serum ultrafiltrate medium, which contained endogenous androgen-estrogen, 110-100 pg and could maintain growth without additional androgen-estrogen. Exogenous androgen-estrogen was also added to some cultures. Scent gland tumors grown in organ culture contained cells of two shapes, spindle and ovoid arranged in cords. Cultures on coverslips showed radiating outgrowths of spindle cells suggesting either mesenchymal or Schwann cells. By electron microscopy, both in vivo and in vitro preneoplastic and tumor samples contained cells with segments of basal lamina, micropinocytotic vesicles, and junctional complexes. These features were similar to those of poorly differentiated experimental malignant rat schwannomas maintained in similar in vitro systems. Tumors grown in vivo and in vitro were associated with collagen fibrils with a periodicity ranging from 400 to 1075 A. The evidence reported in this paper suggests that one component of the scent gland tumor is an androgen-estrogen-induced poorly differentiated schwannoma.