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.
 

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.
 

Non-typhoidal Salmonella (NTS) is a major foodborne zoonotic pathogen worldwide. In the current study, Various NTS strains were isolated from (cows, milk and dairy products in addition to humans) in New Valley and Assiut Governorate, Egypt. NTS were firstly serotyped and tested by antibiotic sensitivity test. Secondly, some virulence genes and Antibiotic resistance genes have been identified by using PCR. Finally, Phylogenesis was performed depending on the invA gene, for two S. typhimurium isolates (one of animal origin and the other of human origin for evaluating zoonotic potential).

Results

Out of 800 examined samples, the total number of isolates was 87 (10.88%), which were classified into 13 serotypes, with the most prevalent being S. Typhimurium and S. enteritidis. Both bovine and human isolates showed the highest resistance to clindamycin and streptomycin, with 90.80% of the tested

The specific arrangement and distribution of photoreceptors in the retina can vary among different fish species, with each species exhibiting adaptations related to its habitat, behavior, and visual requirements. Poecilia sphenops, a diurnal fish, was the focus of this study. The retinas of a total of eighteen Molly fish were investigated utilizing light and electron microscopy. The retina exhibited a square mosaic pattern of the inner segments of cones. This pattern comprised double cones positioned along the sides of a square, with two types of single cones situated at the center and corners of the square arrangement across the entire retina. The corner cones were slightly shorter than the central ones. Additionally, the outer plexiform layer contained both cone pedicles and rod spherules. The rod spherule consisted of a single synaptic ribbon arranged in a triad or quadrat junctional arrangement within the invaginating free ends of the horizontal and bipolar cell processes. On the other hand, cone pedicles have more than one synaptic ribbon in their junctional complex. The inner nuclear layer consisted of the amacrine, bipolar, Müller, and horizontal cell bodies. Müller cell processes, expressing GFAP, extended across all retinal layers, segmenting the deeper retina into alternating fascicles of optic axons and ganglion cells. The outer and inner plexiform layers showed many astrocyte cell processes expressing GFAP. In conclusion, the current study is the first record of the retinal structures of Molly fish. This study illustrated the mosaic arrangement of photoreceptors and GFAP expression patterns of astrocytes and Müller cells. The presence of three cone types, coupled with a sufficient number of rods, likely facilitates motion awareness for tasks like finding food and performing elaborate mating ceremonies.

The structure of photoreceptors (PR) and the arrangement of neurons in the retina of
red-tail shark were investigated using light and electron microscopy. The PR showed
a mosaic arrangement and included double cones, single cones (SC), and single rods.
Most cones occur as SC. The ratio between the number of cones and rods was
3:1.39 (±0.29). The rods were tall that reached the pigmented epithelium. The outer
plexiform layer (OPL) showed a complex synaptic connection between the horizontal
and photoreceptor terminals that were surrounded by Müller cell processes. Electron
microscopy showed that the OPL possessed both cone pedicles and rod spherules.
Each rod spherule consisted of a single synaptic ribbon within the invaginating terminal endings of the horizontal cell (hc) processes. In contrast, the cone pedicles possessed many synaptic ribbons within their junctional complexes. The inner nuclear
layer consisted of bipolar, amacrine, Müller cells, and hc. Müller cells possessed intermediate filaments and cell processes that can reach the outer limiting membrane and
form connections with each other by desmosomes. The ganglion cells were large multipolar cells with a spherical nucleus and Nissl’ bodies in their cytoplasm. The presence of different types of cones arranged in a mosaic pattern in the retina of this
species favors the spatial resolution of visual objects.