This study provides a detailed histological and immunohistochemical analysis of the kidney and adrenal gland in Varanus niloticus (Nile monitor lizard), highlighting their structural features and adaptive mechanisms. Ten adult female Nile monitors were collected from Qena Province, Egypt, and their kidneys and adrenal glands were examined. Kidney tissues were processed for histological analysis, and immunohistochemistry was performed to evaluate the expression of key markers, including vimentin, E-cadherin, CK7, and NSE. In contrast to other reptiles, the kidney was divided into the cortex and medulla and contained a loop of Henle. The cortex contains renal corpuscles and nephron tubules, while the medulla primarily comprises collecting ducts. The proximal tubules were lined with acidophilic cuboidal cells, whereas the distal tubules exhibited pale cuboidal cells with fewer microvilli. Immunohistochemistry revealed vimentin expression in podocytes and a few renal tubule epithelial cells, while E-cadherin was expressed in the distal tubules, loop of Henle, and collecting ducts. NSE was strongly expressed in the renal corpuscles and macula densa of the juxtaglomerular apparatus, as well as in the peripolar cells, but was absent in the proximal tubules. CK7 was predominantly expressed in the distal tubules and collecting ducts. The adrenal glands comprise steroidogenic and chromaffin cells associated with the posterior cardinal veins of the kidney. NSE was strongly expressed in chromaffin cells, while vimentin was detected in steroidogenic cells. E-cadherin and CK7 are not expressed in the adrenal tissues. These findings provide insights into the structural and functional adaptations of the kidney and adrenal glands in Nile monitors, offering a foundation for future research into the comparative anatomy and functional ecology of reptilian excretory and endocrine systems.

Cartilage is a crucial component of the vertebrate skeletal system, providing structural integrity, flexibility, and adaptive functions across species. In teleost fish, cartilage exhibits significant morphological and functional diversity, providing specialized biomechanical properties essential for aquatic life. This study presents a detailed histological, immunohistochemical, and ultrastructural investigation of cartilage in molly fish (Poecilia sphenops), identifying five distinct types of cartilage: hyaline-cell, scleral, 

Background

Synanthropic filth flies thrive in human and animal habitats, posing health risks through the transmission of infectious agents. They breed on organic waste, including animal feces, making them carriers of various pathogens. In Egypt, where livestock farming is common and poor sanitation, these flies may contribute to zoonotic disease transmission. The current study investigates parasitic infections in filth flies from three livestock farms in Assiut Governorate, Upper Egypt, highlighting their role as vectors for zoonotic infections, particularly Cryptosporidium, via morphological and molecular tools.

Methods

A total of 12,749 flies were collected from the study sites via sweep nets. After taxonomic identification, the flies were examined microscopically for parasites using various concentration and staining techniques. Positive samples were further confirmed for infections, particularly for Cryptosporidium parasites, via nested PCR and sequence analysis targeting the COWP and SSU rRNA genes.

Results

This study revealed the presence of several fly species from seven dipteran families, particularly the family Muscidae, primarily Musca domestica, which presented a high parasite infestation rate of 96.6%. This study revealed a high prevalence of various protozoans and helminths in the collected flies. Cryptosporidium was the most prevalent parasite (64.4–100%), infecting all fly species. Entamoeba and Balantidium were also significant, especially in M. domestica (22.6–90.1%, 8.9–100%), Fannia canicularis (10.5–74.4%, 44.2–88.2%), and Borborillus vitripennis (11.1–50%, 37.2–91.4%). Giardia, Trichuris, and Trichostrongylidae had low to moderate prevalence in multiple fly species. Mites are commonly detected on fly exoskeletons, with high infestation rates observed in Musca domestica (77–100%) and Physiphora alceae (66.7–100%). The present study also reported sporadic infections with Trichomonas, Toxocara vitulorum, and pseudoscorpions, along with notable midge larval infestations (52.1%), mainly at site B. Parasitic infections were highest in autumn and spring, with the lowest rates in winter. Molecular identification confirmed the presence of the zoonotic species Cryptosporidium parvum and Cladotanytarsus gedanicus.

Conclusion

This study revealed that zoonotic parasites exist in flies and pose potential risks when they are found near humans. Cryptosporidium parvum is the prevalent parasite causing diarrhea outbreaks in animals. This is the first genetic evidence of Cladotanytarsus gedanicus midge from Upper Egypt.

Spermatogenesis in teleosts is essential for reproductive function; however, it varies considerably among species. The testis of the viviparous molly fish (Poecilia sphenops) was
examined using both ultrastructural and immunohistochemical methods. The testis displays a restricted lobular type, where germ cells develop synchronously within Sertoli
cell-forming cysts. Transmission electron microscopy (TEM) revealed all stages of spermatogenesis. Mature sperm are at the apex of the cysts and migrate toward the sperm
ducts. Sperm duct epithelium is lined by cuboidal cells joined by tight junctions, with
apical cilia and desmosomal complexes contributing to transport and structural integrity.
The sperm ducts showed strong Periodic Acid–Schiff (PAS)-positive expression among
negative stained spermatocysts. Centrally, a cavity serves as a storage area for spermatozoa
that are organized into unencapsulated bundles known as spermatozeugmata. Sertoli cells
exhibited extended cytoplasmic processes that supported developing germ cells, whereas
Leydig cells occupied the interstitial tissue, contributing to hormonal regulation. Immunohistochemical labeling demonstrated strong vimentin expression in Sertoli cells and
telocytes, indicating their mesenchymal origin and structural role. Calretinin expression
was confined to Leydig cells and certain ductal epithelial cells, supporting its use as a
marker for steroidogenic and secretory functions. These findings provide new insights into
the testicular specialization of P. sphenops, highlighting key somatic–germ cell interactions,
ductal adaptations, and marker expression patterns that underlie male reproductive success
in viviparous fish 
 

The spleen plays a critical role in the immune and hematopoietic systems of
teleost fish, functioning as a major secondary lymphoid organ. This study provides a
detailed morphological and ultrastructural assessment of the spleen in goldfish (Carassius
auratus), focusing on its immunological organization and cellular diversity. Through light
and transmission electron microscopy, we examined red and white pulps, identifying key
features such as melanomacrophage centers (MMCs), ellipsoids, and various immune cell
types. The red pulp was rich in sinusoidal capillaries and splenic cords, whereas the white
pulp housed lymphocytes, dendritic cells, macrophages, and telocytes, all contributing to
immune regulation. Notably, ellipsoids were surrounded by reticular and macrophage
sheaths, forming a filtration barrier against pathogens. Ultrastructural analysis revealed
diverse immune cells with active morphological traits, including macrophages with pseudopodia and pigment granules, dendritic cells with dendrite-like extensions, and epithelial
reticular cells involved in forming the blood–spleen barrier. These findings highlight
the complex immunological microarchitecture of the goldfish spleen and its functional
relevance in teleost immune responses 
 

The kidneys of molly fish (Poecilia sphenops) exhibit complex immune and cellular activities, which
are crucial for maintaining renal function and responding to environmental stressors. This study
aimed to investigate the histological and immunohistochemical characteristics of immune cells,
autophagy, and stem cell activity within the renal tissues of molly fish. Histological analysis revealed
the presence of immune cells, including macrophages and granular leukocytes, concentrated around
the renal corpuscles (RC) and renal tubules (RT). Additionally, numerous lymphocytes were observed
surrounding the RC, and a notable presence of rodlet cells with a thick capsule and rodlet-like
inclusions was detected around the RT. Immunohistochemical staining confirmed macrophage activity
through CD68 and Iba1 expression, while APG5, an autophagy marker, was observed in macrophages,
rodlet cells, and podocytes, indicating active autophagic processes. Polymorphic granulocytes
expressed iNOS-2. Inflammatory markers IL-1β and NF-κB were highly expressed in rodlet cells and
macrophages, respectively, suggesting their role in immune modulation. The expression of S100
protein in rodlet cells and acetylcholine in macrophages further highlights their specialized functions
in immune regulation. Additionally, renal stem cells were identified by expressing Nrf2 and Sox9,
indicating a potential role in tissue repair and regeneration. These findings provide critical insights into
the kidney’s dual function in immunity and regeneration, contributing to a better understanding of
fish renal physiology and potential applications in environmental monitoring and aquaculture health
management.