Cytodifferentiation of Wulzen's cone of mature male sheep hypophysis cerebri with special emphasis on its parenchymal correlations with the adjacent Pars distalis, Pars intermedia and Pars nervosa

Background: Hypophysis cerebri is considered the master endocrine gland as it plays a directly critical roles in influencing and controlling the vitality of other endocrine organs via several hormones secretion. Aim: The present study was performed to clarify the localization of Wulzen's cone within sheep hypophysis and cytodifferentiation of the glandular cells filling cone parenchyma with special emphasis on the cone correlations with adjacent pars distalis, pars intermedia and pars nervosa. Methods: Pituitaries were collected and processed histologically then subjected to different combinations of special stains; Br-AB- OFG., PFA-AB-PAS-OG., PAS-Orange G., Orange G- Acid Fuchsin- Light Green, Bielschowsky technique, Masson's trichrome and Gomori's reticulin. Results: A sagittal section through pituitaries revealed a well-developed cone of glandular cells protruded from the pars intermedia like a tongue plate towards the hypophyseal cleft in the neighborhood of the pars distalis and behind to the pars nervosa. Resembling the pars distalis, various glandular cells were distinguished in the cone; chromophobes and chromophils of acidophils and basophils. The cone is mainly formed from acidophils intermingled with the chromophobes. Meanwhile, basophils were mainly localized at the most anterior and posterior part of the cone. In front of the cone, pars distalis were localized resembling a wing- shaped and filled with several categorized glandular cells; chromophobes and chromophils. Upper to the cone, pars intermedia were localized and composed mainly with weakly basophilic cuboidal or polygonal cells that arranged in parallel cords or in follicles. Behind to the cone, pars nervosa was localized as a ventral out pouching of the brain floor like a water- drop. Unlike the cone, it was devoid from any glandular secretory cells or nerve cells but consisted mainly of unmyelinated nerve fibers, herring bodies and pituicytes. Conclusion: Wulzen's cone is present and well-developed in sheep adenohypophysis. Various glandular cells were distinguished filling the cone, chromophobes and chromophils of acidophils and basophils that were typically similar to the glandular cells of pars distalis but with different distributions. [Open Vet J 2023; 13(3.000): 307-321

Cytodifferentiation of pinealocytes (I and II) and astrocyte types of mature male sheep epiphysis cerebri with special emphasis on the presence of neuronal and pigmented like cells

Background: The epiphysis cerebri (pineal gland) is a small-sized, photo neuroendocrine organ in the brain of most vertebrates. Their effect is through secretion of melatonin, a serotonin-derived hormone which is stimulated by darkness and inhibited by light and modulates the circadian rhythm; light and dark cycle like a biological clock, sleep patterns (sleep-wake cycle) and sexual development. Aim: This study aimed to identify and differentiate the different cell types filling the pineal gland parenchyma of mature male sheep. Methods: Pineal glands were collected and sliced parasagitally then processed histologically for light and electron microscopic examinations. Results: Two main cell types; pinealocytes and astrocytes were recognized within the gland parenchyma. Pinealocytes were the chief parenchymatus cells occupied the largest volume of the gland and were classified according to the nuclear pictures (activity status) into two subtypes; pinealocytes I (pale subtype, active) and II (dark subtype, in active). Astrocyte neuroglial cells had cytoplasmic processes which forms a huge supportive framework between the pinealocytes and clarified two types; type I were elongated cells with elongated snake shaped nucleus and type II were smaller in size, with oval nuclei. Another marginal cell type was identified as a neuron-like cell which appeared larger in size than others and distributed sporadically, has eccentric oval nucleus with prominent nucleoli and single, long cytoplasmic process that branched at its terminal forming T-shaped process looks like pseudo unipolar neuron. Moreover, aggregations of pigment granules were markedly observed in the intercellular spaces and also near the blood capillaries. With TEM a special characteristic feature of pinealocytes; synaptic ribbons were recognized that appeared as bands of electron-dense material with several synaptic spherules; vesicles adjacent to its surface helping in the multivesicular release. Conclusion: The gland parenchyma revealed two main cell types; pinealocytes and astrocytes. Each one was subdivided to two subtypes; I and II. The first one was classified according to their nuclear pictures (activity status) and the second one was according to their shape, size and cytoplasmic processes. Other cell types were also identified as neuronal and pigmented like cells in the pineal matrix. [Open Vet J 2023; 13(2.000): 206-217

Restricted localization of ultimobranchial body remnants and parafollicular cells in the one-humped camel (Camelus dromedarius)

Parafollicular cells (C-cells) exist within the thyroid glands and display different distributions within the glands among mammalian species. In the one-humped camel (Camelus dromedarius), localization of the C-cells remains under debate. We herein investigated appearance of C-cells and the remnants of the ultimobranchial body, origin of C-cells, in the thyroid glands of one-humped camels. Macroscopically, a white mass was present at one-third the length from the cranial end of the thyroid glands where the cranial thyroid artery entered. In addition, large fossae were frequently found adjacent to the white mass. Histologically, the mass was mainly composed of connective tissues, thyroid follicles, and two types of cell clusters: one was composed of cells with clear cytoplasm and the other was composed of non-keratinized epidermoid cells. The mass and the fossae contained p63-positive cells, indicating that they consisted of ultimobranchial body remnants. Calcitonin was expressed in cells with clear cytoplasm, which were localized just beneath the fossae and in the cell clusters of the white mass. C-cells also resided in both subfollicular and interfollicular spaces adjacent to the white mass, but gradually decreased toward the periphery. C-cells tended to display round shapes in the ultimobranchial body remnants and subfollicular spaces, and spindle shapes in interfollicular spaces. In conclusion, we demonstrated that the ultimobranchial body remnants were limited to the region around the entrance of cranial thyroid artery and vein, and C-cells were mainly concentrated within and around the ultimobranchial body remnants