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Introduction: Ocular diseases pose a significant health concern for donkeys. However, studies examining the microanatomy and cell populations of the donkey retina are scarce. The current study aimed to describe the vascular pattern of the donkey retina and document its cellular components. Methods: The donkey retina specimens were obtained from different retinal regions and prepared for semithin sectioning and immunohistochemistry. Results: The donkey has a paurangiotic retina in which retinal vessels are confined to a narrow area around the optic disc. Glial cells coexist with the blood vessels being very numerous in the vascular region and become scanty in the avascular ones. S-100-positive astrocytes could be observed in these avascular areas. Ganglion cells are organized in a single layer with the least population existing in the peripheral retina. Acidic fibroblast growth factor (AFGF) is immunoreactive in amacrine and ganglion cells. A subpopulation of amacrine cells reacted strongly to tyrosine hydroxylase (TH), and others reacted positively to S-100 protein. Ganglion cell nuclei exhibited a strong immunoreactivity to S-100 protein as well. Furthermore, glial fibrillary acidic protein (GFAP) is used to identify Müller cells that extend their processes across the retina from the inner to the outer limiting membrane. Conclusions: In conclusion, our findings provide novel insights into the normal retinal organization. The donkey retina shows the characteristic expression of immunohistochemical markers for the major cell types. In addition, the distribution of glial cells is comparable between the vascular and avascular regions. [ABSTRACT FROM AUTHOR]

Teleost fish exhibit the most pronounced and widespread adult neurogenesis. Recently, functional development and the fate of newborn neurons have been reported in the optic tectum (OT) of fish. To determine the role of neurogenesis in the OT, this study used histological, immunohistochemical, and electron microscopic investigations on 18 adult Molly fish specimens (Poecilia sphenops). The OT of the Molly fish was a bilateral lobed structure located in the dorsal part of the mesencephalon. It exhibited a laminated structure made up of alternating fiber and cellular layers, which were organized into six main layers. The stratum opticum (SO) was supplied by optic nerve fibers, in which the neuropil was the main component. Radial bipolar neurons that possessed bundles of microtubules were observed in the stratum fibrosum et griseum superficiale (SFGS). Furthermore, oligodendrocytes with their processes wrapped around the nerve fibers could be observed. The stratum album centrale (SAC) consisted mainly of the axons of the stratum griseum centrale (SGC) and the large tectal, pyriform, and horizontal neurons. The neuronal cells of the SO and large tectal cells of the SAC expressed autophagy‐related protein‐5 (APG5). Interleukin‐1β (IL‐1β) was expressed in both neurons and glia cells of SGC. Additionally, inducible nitric oxide synthase (iNOS) was expressed in the neuropil of the SAC synaptic layer and granule cells of the stratum periventriculare (SPV). Also, transforming growth factor beta (TGF‐β), SRY‐box transcription factor 9 (SOX9), and myostatin were clearly expressed in the proliferative neurons. In all strata, S100 protein and Oligodendrocyte Lineage Transcription Factor 2 (Olig2) were expressed by microglia, oligodendrocytes, and astrocytes. In conclusion, it was possible to identify different varieties of neurons in the optic tectum, each with a distinct role. The existence of astrocytes, proliferative neurons, and stem cells highlights the regenerative capacity of OT. Research Highlights: The OT of the Molly fish exhibited a laminated structure made up of alternating fiber and cellular layers, which were organized into six main layers.Radial bipolar neurons that possessed bundles of microtubules were observed in the stratum fibrosum et griseum superficiale (SFGS).The stratum album central (SAC) consisted mainly of the axons of the stratum griseum centrale (SGC) and the large tectal, pyriform, and horizontal neurons.Inducible nitric oxide synthase (iNOS) was expressed in the neuropil of the SAC synaptic layer and granule cells of the stratum periventricular (SPV). Also, transforming growth factor beta (TGF‐β), SRY‐box transcription factor 9 (SOX9), and myostatin were clearly expressed in the proliferative neurons.The existence of astrocytes, proliferative neurons, and stem cells highlights the regenerative capacity of OT. [ABSTRACT FROM AUTHOR]

Unlike adult mammalian cardiomyocytes, cardiomyocytes in teleosts display high proliferative capacity throughout adulthood. This study aimed to identify the immunohistochemical profiles of cardiomyocytes and immune cells in the hearts of Molly fish by assessing the immunolabelling expression of key proteins involved in cell proliferation, differentiation, and tissue protection. The cardiac anatomy of Molly fish includes the atrium, ventricle, and bulbus arteriosus. The expression of SOX9, NF-κB, myostatin, and S100 proteins in myocardial cells indicates the proliferative features of the heart in Molly fish. The bulbus arteriosus is characterized by collagenous chambers and smooth muscle cells that express Ach and iba1. The atrium of Molly fish serves as a storage unit for rodlet cells and immune cells. Rodlet cells displayed immunoreactivity to NF-κB, iba1, Olig2, Ach, and S100 proteins, suggesting their roles in the immune response within the heart. Furthermore, telocytes (TCs) have emerged as a significant component of the atrium of Molly fish, expressing Ach, CD68, S100 protein, and iba1. These expressions indicate the involvement of TCs in multiple signaling pathways that contribute to heart architecture. This study delineates the intricate relationship between cardiomyocytes and innate immune cells in Molly fish. [ABSTRACT FROM AUTHOR]

The bulbus arteriosus of goldfish, Carassius auratus, possesses unique structural features. The wall of the bulbus arteriosus is exceptionally thick, with an inner surface characterized by longitudinally arranged finger-like ridges, resulting in an uneven luminal appearance. These ridges are covered by endocardium and encased in an amorphous extracellular matrix. The inner surface of the bulbus arteriosus also contains rodlet cells at different developmental stages, often clustered beneath the endothelium lining the bulbar lumen. Ruptured rodlet cells release their contents via a holocrine secretion process. The high abundance of rodlet cells in the bulbus arteriosus suggests that this is the site of origin for these cells. Within the middle layer of the bulbus arteriosus, smooth muscle cells, branched telocytes (TCs), and collagen bundles coexist. TCs and their telopodes form complex connections within a dense collagen matrix, extending to rodlet cells and macrophages. Moreover, the endothelium makes direct contact with telopodes. The endocardial cells within the bulbus arteriosus display irregular, stellate shapes and numerous cell processes that establish direct contact with TCs. TEM reveals that they contain moderately dense bodies and membrane-bound vacuoles, suggesting a secretory activity. TCs exhibit robust secretory activity, evident from their telopodes containing numerous secretory vesicles. Furthermore, TCs release excretory vesicles containing bioactive molecules into the extracellular matrix, which strengthens evidence for telocytes as promising candidates for cellular therapies and regeneration in various heart pathologies. [ABSTRACT FROM AUTHOR]

The microanatomy of the donkey eye is important to understand because pathological disorders affecting them are relatively common. The current study aimed to document the cellular components of donkey's retinae using light and electron microscopic studies. Ten donkey retinae were dissected and processed for semi-thin sections and electron microscopic studies. The photoreceptor layer was made up of the outer and inner segments of rods and cones. The outer segments were filled with invaginations of cell membranes that form stacks of membranous disks. Shed discs of photoreceptor outer segments could be seen in the photoreceptor layer as well as near the Müller cells. The inner segments of cones were conical in shape, while those of rods were slim rod-shaped. Both were filled with long thin mitochondria and free ribosomes. Three rows of photoreceptor cell nuclei made up the outer nuclear layer. The rod nuclei had more electron-dense chromatin than those of the cones. There were two rows of cell nuclei in the inner nuclear layer that represent the following four cell classes: horizontal cells, bipolar cells, amacrine cells, and Müller cells. Bipolar cells constitute the bulk of the inner nuclear layer. They were elongated in shape and had thick branched dendrites. Amacrine cells were in the inner face of the INL. It could be observed within IPL and known as displaced amacrine cells. Muller glial cells were irregular elongated in shape with many cytoplasmic processes. They were distributed in the INL among the bipolar cells. Müller cells were observed in the inner plexiform layer, the ganglion cell layer, and the nerve fiber layer. In conclusion, this study characterized the detailed cytological organization and ultrastructure of the healthy donkey retina. which maintains the fundamental laminar architecture characteristic of other mammalian retinas, and consists of 10 distinguishable layers. When compared to previously described retinal morphologies in domestic species, some distinctive characters were observed in donkey retinal cells. [ABSTRACT FROM AUTHOR]

The epididymis, a key component of the male reproductive system, controls spermatozoa's maturation, fertility, and storage. The objective of this study is to evaluate the histological, ultrastructural, and immunohistochemical variations in the epididymis of donkeys that occur throughout the year. During the breeding season (spring) and nonbreeding seasons (summer, autumn, and winter), 20 epididymis were collected from adult, clinically healthy donkeys. Compared to non‐breeding seasons, the epididymal duct displayed a more active lining epithelium and more sperm in the lumen during the breeding season. The epithelial height is the lowest and the lumen is the widest during the breeding season. Furthermore, the epididymal epithelium in the tail region exhibits undulations with polyps‐like projections. The epididymal epithelium is composed mainly of the principal, basal, and dark cells. Tight junction between adjacent principal cells is more obvious in the breeding season as compared to the non‐breeding seasons. However, intraepithelial lymphocytes, phagocytic, and other immune cells are more frequent in non‐breeding seasons. β‐catenin, which is a component of the adherent junctions between adjacent PCs, exhibits more immunoreactivity during the spring. On the other hand, iNOS, an indicator of oxidative stress, reacts positively during the summer. Additionally, during non‐breeding seasons, autophagy was detected within the epididymal epithelium which may be linked to stress adaptation. In conclusion, our findings suggest that the histological and ultrastructural characteristics of the epididymal epithelium are more active during spring compared to other seasons of the year. Research Highlights: The study aimed to evaluate the histological, ultrastructural, and immunohistochemical variations in the blood epididymal barrier (BEB) and epididymal epithelium of donkeys that occur throughout the year.In comparison to non‐breeding seasons, the epididymal duct displayed a more active lining epithelium and more sperm in the lumen during the breeding season.The epithelial height is the lowest and the lumen is the widest during the breeding season.The epididymal epithelium in the tail region exhibits undulations with polyps‐like projections that increase the surface area.β‐catenin, which is a component of the adherent junctions between adjacent PCs, exhibits more immunoreactivity during the spring. On the other hand, iNOS, an indicator of oxidative stress, reacts positively during the summer. [ABSTRACT FROM AUTHOR]

Fish's skin serves a variety of functions that are essential for survival, including communication, respiration, sensory perception, excretion, ion regulation, and heat regulation. This research aimed to examine the snout skin of koi fish (Cyprinus carpio) to determine its structural characteristics. Using light microscopy, the histochemical elements of the skin were examined in a total of 20 adult, healthy koi fish. The skin of was made up of three layers: epidermis, dermis, and hypodermis. The epidermis consisted of epidermal cells, club cells, mucous goblet cells, rodlet cells, eosinophilic granular cells, serous goblet cells, and melanocytes. large amounts mucous of cells which reacted positive to Alcian blue (AB) and Periodic Acid-Schiff (PAS), few club cells which reacted positive to bromophenol blue and light green. many eosinophilic granular cells (EGCs) reacted positive to PAS and light green. Moreover, many taste buds also were demonstrated. The dermis was consisted of collagenous bundles, bundles of myelinated nerve fibers, blood vessels and immune cells. Many telocytes were detected in dermis in close relation to nerve fibers, blood vessels and immune cells. The lateral line system was well-developed in koi fish, where it was arranged into mechanoreceptive superficial and canal neuromasts and electroreceptive tuberous and ampullary organs. In conclusion, the epidermis of snout region in Koi fish consisted of a variety of cells with diverse functions. [ABSTRACT FROM AUTHOR]

The precise role of the nictating membrane is uncertain and inconsistently discussed in the literature, it is still up for debate. Currently, there have been no extensive investigations on the effect of nictating membrane excision on tear production in donkeys. Therefore, the current study aimed to evaluate the effects of total or partial surgical resection of the nictitating membrane on aquous tear production, pH, and corneal integrity via fluorescein dye and histological examination in donkeys. Donkeys were allocated into two equal groups. Group I (5 donkeys): donkeys were subjected to complete resection of the third eyelid in the left eye and the right one was a control. Group II (5 donkeys), donkeys were subjected to partial resection of the third eyelid in the left eye, and the right one was a control. All animals were observed for three months postoperative. The following criteria (ophthalmic examination, Schirmer tear test I (STT I), tear pH, and fluorescein staining test) were used for the evaluation of the eyes weekly for the first two months, then every two weeks for the last month. There were no significant variations in the mean values of STT I and pH of the total resection of the third eyelid (group Ι) in comparison with the partial resection of the third eyelid (group ΙΙ) (P > 0.05). In both eyes, there were no obvious clinical indicators of keratoconjunctivitis sicca (KCS). The histopathological examination of various regions such as eyelids, cornea, and conjunctiva in both groups compared to the control showed that all regions were perfectly normal. However, acinar atrophy, degeneration and periacinar fibrosis were visible in the glandular tissue of the third eyelid and cystic dilation and periductal fibrosis were visible in the nictitans gland's duct system. In conclusion, neither complete nor partial resection of the third eyelid causes the development of KCS or alters the ocular surface integrity. [ABSTRACT FROM AUTHOR]

Prolapsed nictitans gland is a common affection in dogs. Several treatment options have been suggested such as removal of the prolapsed nictitans gland, excision of the third eyelid, or repositioning of the gland. Keratoconjunctivitis sicca (KCS) was reported to occur after excision of the prolapsed gland or the third eyelid, while recurrence is commonly associated with repositioning surgery. Therefore, the aim of this study was to investigate the effect of excisions of the nictitans gland or third eyelid on ocular surface integrity, pH, and tear production. Nictitans gland or third eyelid were excised surgically from healthy eyes in dogs. Corneal integrity, pH, and tear amount were examined for 7 months. Histological examination was performed after 7 months of surgery. Fluorescein staining was negative at the different time points in both groups. No significant change was observed in pH after excision of the third eyelid. In contrast, pH was significantly decreased after 2 weeks of removal of the nictitans gland. Tear amount was significantly declined 2 and 3 weeks after excision of the third eyelid and 3 weeks after excision of nictitans gland. The histological examination of different regions including, eyelids, cornea and conjunctiva in both groups compared to control revealed that all parts were completely normal. However, closer to the site of the third eyelid operation severe desquamation of epithelium and infiltration of inflammatory cells were observed. In conclusion, neither excisions of the third eyelid nor the nictitans gland induce the development of KCS or affect the ocular surface integrity. [ABSTRACT FROM AUTHOR]

Diabetes mellitus is a complex metabolic syndrome that involves dysfunction of spleen and other lymphoid organs. Medicinal plants, including okra ( Abelmoschus esculentus (L.) Moench), were used widely for diabetes treatment. Scarce data are available about the potential anti-diabetic effects of okra, the histopathological alterations in splenic tissues and the mechanistic pathways underlying this association. The current research investigated the effects of okra pod extract on the biochemical parameters and expression of CD8 + T cells and nuclear factor kappa (NF-k) B and releasing proinflammatory cytokines in spleen in streptozotocin (STZ)-induced diabetic rat models. A total of 50 mature male Wister albino rats were divided into five isolated groups; the first served as control (untreated) animals, the second (DM group) diabetes induced by STZ (at a dose of 45 mg/kg body weight, administered intraperitoneally), the third group (DM + Insulin): diabetic rats administered insulin subcutaneously (10 units/kg bw/day) daily for 4 weeks, the fourth group was administrated 400 mg/kg okra extract daily for 4 weeks, and diabetic induced rats in the fifth group were administrated 400 mg/kg okra extract daily for 4 weeks. The 2,2-diphenyl-1-picrylhydrazyl (DPPH) scavenging activity in Abelmoschus esculentus (L.) Moench was studied, and the content of phenolic compounds in okra pods was estimated using high-performance liquid chromatography. Diabetes induction led to decreased body weight, increased blood glucose levels. Capsular thickness was significantly increased, white pulp was widely dispersed, and mature lymphocytes in the periphery were also drastically decreased, with thick follicular arteries, necrosis, and depletion of lymphocytes in the germinal center. Red pulp revealed severe congestion and degenerative changes, deposition of hemosiderin granules and lymphocytic depletion. In addition, collagen fiber deposition was increased also in this group. The induction of diabetes exaggerated NF-kβ expression and mediated downregulation of the expression of CD8 + T cells in spleen tissue. Interestingly, oral administration of okra extracts post diabetes induction could mitigate and reverse such adverse effects. Altogether, our study points out the potential benefits of okra in improving blood glucose levels and restoring histopathological alterations in splenic tissues through CD8 + T cells and NF-kβ expression in a diabetic rat model., Competing Interests: The authors declare that the research was conducted in the absence of any commercial or financial relationships that could be construed as a potential conflict of interest., (Copyright © 2023 Alblihd, Alsharif, Hamad, Ali, Hussein, Alhegaili, Hassan, Al-Amer, Albezrah, Almalki, Albarakati, Alghamdi, Alzahrani, Albrakati, Alrubai, ElAshmouny and Elmahallawy.)