Doaa M. Mokhtar

Melatonin administration induced reactivation in the seminal gland of the soay rams during non-breeding season: An ultrastructural and morphometrical study

Fifteen adult Soay rams were used in this experiment. Eight animals were given subcutaneous implants containing melatonin, while the other seven animals were used as control. After 11 weeks, the rams were killed and the seminal vesicles were examined by light and electron microscope. In contrast to the control grouped animals, the melatonin treated rams showed morphological, morphometrical, and ultrastructural changes as a result of reactivation of the glandular tissues of the seminal glands. The ratio of interstitial connective tissues to glandular tissues was reduced in the treated group. Melatonin induced an evident significant increase in number and height of principal cells that showed signs of increased secretory activity; apical cytoplasmic protrusions became well developed and covering the inner surface of the glandular end‐pieces, also, the basal cells were significantly increased in number. The main cytological alteration in the principal cells of the seminal vesicles in treated animals was prominent increase in the concentrically arranged membranes of sER, secretory vacuoles and glycogen granules and appearance of numerous lysosomes and multivesicular bodies. Interstitial Cajal‐ like cells were significantly increased in number and formed a network around the epithelium and between smooth muscle cells in the treated group. The main components of these cells were mitochondria, rER, sER, and many caveolae. The cytological alterations were accompanied by subepithelial and intraepithelial nonmyelinated nerve terminals in the treated animals. The results support the view that melatonin activates and increases the secretory activity of seminal gland in sheep. J. Morphol. 277:231–243, 2016.

Comparative Histomorphological Studies on Oesophagus of Catfish and Grass Carp

The present work was carried out on 40 specimens of oesophaguses of both sexes of catfish (carnivorous fish) and grass carp (herbivorous fish) in order to observe the morphological and histological differences between the two species. Oesophagus of catfish was divided into 2 parts: anterior and posterior ones. The anterior part of the oesophagus of catfish was characterized by the presence of numerous mucosal folds. It was lined by stratified epithelium with goblet cells. In addition to club cells were observed in between the stratified epithelium. Scanning electron examination of the oesophageal epithelium of catfish demonstrated the presence of microvilli and fingerprint-like microridges in the superficial cell layer. The posterior part of the oesophagus of catfish was characterized by simple columnar mucus-secreting epithelium. The oesophagus of grass carp had shown the same structure along its entire length. It consisted of less folded mucosa than that observed in the oesophagus of catfish. The epithelium was characterized by the presence of taste buds. In conclusion, the present work revealed some differences in the structure of catfish oesophagus and grass carp oesophagus. These differences are related to type of food and feeding habits of each species.

Microscopic and histochemical characterization of the bovine uterine tube during the follicular and luteal phases of estrous cycle

The morphometrical and morphological features of the infundibulum and ampulla of the uterine tubes of adult cattle were studied. The materials used in this study were consisted of 12 pairs of uterine tube of healthy cows at age of 16–36 months, collected from Assiut slaughterhouses. Through observations of the ovaries, follicular and luteal phases of estrous cycle of each cattle were specified. Semithin sections of ampulla and infundibulum at follicular and luteal phases were made and histochemical analysis of the ampulla by use of PAS, Alcian Blue, Sudan Black B was also done. In addition, acid phosphatase activity of the ampullar epithelium was demonstrated. Histological analysis of the epithelium of bovine oviduct revealed that it was consisted of non-ciliated secretory cells, two populations of ciliated cells (CC), basal cells and Peg cells. At the luteal phase, the secretory cells possessed many cytoplasmic protrusions that extended beyond the luminal borders of the ciliated cells and exocytosis of secretory materials was observed. While at the follicular phase, the ciliated cells were predominated. The histochemistry of the ampullar epithelium revealed increase in secretions of neutral, acidic mucopolysaccarides and lipid from the secretory cells at the luteal phase with moderate acid phosphatase activity. Histomorphometric examinations of infundibulum and ampulla indicated that the mean number and height of primary folds as well as the thickness of the epithelium were increased significantly at the follicular phase.

Identification of morphological markers of sarcopenia at early stage of aging in skeletal muscle of mice

The gastrocnemius muscle (GM) of young (3months) and aged (12months) female wild-type C57/BL6 mice was examined by light and electron microscopy, looking for the presence of structural changes at early stage of the aging process. Morphometrical parameters including body and gastrocnemius weights, number and type of muscle fibers, cross section area (CSA), perimeter, and Ferets diameter of single muscle fiber, were measured. Moreover, lengths of the sarcomere, A-band, I-band, H-zone, and number and CSA of intermyofibrillar mitochondria (IFM), were also determined. The results provide evidence that 12month-old mice had significant changes on skeletal muscle structure, beginning with the reduction of gastrocnemius weight to body weight ratio, compatible with an early loss of skeletal muscle function and strength. Moreover, light microscopy revealed increased muscle fibers size, with a significant increase on their CSA, perimeter, and diameter of both type I and type II muscle fibers, and a reduction in the percentage of muscle area occupied by type II fibers. Enhanced connective tissue infiltrations, and the presence of centrally nucleated muscle fibers, were also found in aged mice. These changes may underlie an attempt to compensate the loss of muscle mass and muscle fibers number. Furthermore, electron microscopy discovered a significant age-dependent increase in the length of sarcomeres, I and H bands, and reduction on the overlapped actin/myosin length, supporting contractile force loss with age. Electron microscopy also showed an increased number and CSA of IFM with age, which may reveal more endurance at 12months of age. Together, mice at early stage of aging already show significant changes in gastrocnemius muscle morphology and ultrastructure that are suggestive of the onset of sarcopenia.

Effect of Melatonin on Telocytes in the Seminal Vesicle of the Soay Ram: An Immunohistochemical, Ultrastructural and Morphometrical Study

Telocytes (TCs) are a special type of interstitial cell with characteristic cellular processes that are described in many organs. The current study aimed to investigate TCs in seminal vesicles of the Soay ram responding to melatonin treatment during the nonbreeding season by conventional immunohistochemical stains, and to detect the ultrastructural and morphometrical changes of TCs. TCs in the control group showed a broad range of staining affinity and also reacted positively to CD117/c-kit, CD34, desmin, S-100 protein, and progesterone and estrogen receptors alpha, while after melatonin treatment a strong reaction against these 6 antibodies was recorded. Electron microscopically, TCs in the control group were characterized by a small cell body with distinct long cytoplasmic extensions called telopodes (Tps). Tps had alternation of the thin segment (podomers) and dilated segments (podoms), in which the latter accommodate mitochondria, rough endoplasmic reticulum and caveolae. TCs and their Tps were interconnected by homo- and heterocellular junctions and form a wide network to communicate between different cell types. Tps showed close contact with immune cells, progenitor stem cells, smooth muscle cells and other interstitial cells. Melatonin caused a significant increase in the number of TCs, length of Tps, and number and diameter of secretory vesicles. Also, the melatonin-treated group showed exaggerated secretory activity in the form of a massive release of secretory vesicles from Tps. Moreover, Tps showed an increase in their contact with blood and lymphatic capillaries, nerve endings and Schwann cells. In addition, the shedding of secretory structures (exosomes, ectosomes, and multivesicular bodies) was greater from Tps, which were involved in paracrine signaling in the melatonin-treated group. The length and ramifications of Tps together with the intercellular junctions and the releasing of shed vesicles or exosomes assumed an essential role of TCs in intercellular signaling and coordination. On the basis of their distribution and morphology, we investigated whether the different locations of TCs could be associated with different roles.

Light and Scanning Electron Microscopic Studies on the Intestine of Grass Carp (Ctenopharyngodon idella): II-Posterior Intestine

The present work was carried out on 20 specimens of grass carp in order to observe the morphological features of intestine. The present study showed that the intestine was long, which may help in retention of food for a longer period of time to ensure proper digestion. Also, the percent of relative gut length (RGL) of grass carp was 1.92%. This RGL with a large intestinal diameter of this species allowing increase the storage capacity of food. The intestine of grass carp were divided into anterior, posterior intestine and rectum. There were no intestinal villi or multicellular intestinal glands in any regions of intestine. The most important features of anterior intestine were a wide diameter of the lumen and a great number and height of mucosal folds. The anterior intestine was lined by simple columnar epithelium, intercalated with goblet cells, wandering lymphocytes and enteroendocrine cells. Scanning electron microscopy, revealed presence of long wavy mucosal folds that formed of enterocytes covered with numerous microvilli, intermingled with numerous openings for goblet cells.

Melatonin Elicits Stimulatory Action on the Adrenal Gland of Soay Ram: Morphometrical, Immunohistochemical, and Ultrastructural Study

Endogenous melatonin is a hormone secreted by pineal gland; it has several roles in metabolism, reproduction, and remarkable antioxidant properties. Studies on the melatonin effect on the adrenal glands which are important endocrine organs, controlling essential physiological functions, are still deficient. In this study, we attempted to investigate the effect of exogenous melatonin treatment on the adrenal cortex and medulla using several approaches. Adrenal glands of 15 Soay ram were examined to detect the effect of melatonin treatment. Our results revealed that the cells of adrenal cortex of the treated animals were separated by wide and numerous blood sinusoids and showed signs of increase steroidogenic activity, which are evidenced by functional hypertrophy with increase profiles of mitochondria, smooth endoplasmic reticulum, and lipid droplets. The most striking ultrastructural features in the medulla of the treated group were the engorgement of chromaffin cells with enlarged secretory granules enclosed within a significantly increased diameter of these cells. The cytoplasm of these cells showed numerous mitochondria, rough endoplasmic reticulum (rER), Golgi apparatus, lysosomes, and glycogen granules. Exocytosis of secretory granules to the lumen of blood vessels was evident in the treated group. Piecemeal degranulation mode of secretion was recorded after melatonin treatment. Chromaffin cells in the control group expressed moderate immunoreactivity to Synaptophysin and tyrosine hydroxylase, compared with intensified expression after melatonin treatment. The ganglion cells of the melatonin-treated group showed a significant increase in diameter with numerous rER. The most interesting feature in this study is the presence of small granule chromaffin cells (SGC) and telocytes (TCs) for the first time in the adrenal glands of sheep. Moreover, these SGC cells, Schwann cells, fibroblasts, and progenitor stem cells showed a stimulatory response. The TCs were small branched cells scattered in the adrenal glands around cortical cells, chromaffin cells, nerve fibers, and blood vessels. These cells increased significantly in number, length of their telopodes, and secretory activity after melatonin treatment. In addition, multiple profiles of unmyelinated nerve fibers were demonstrated in all treated specimens. These results indicated that melatonin treatment caused a stimulatory action on all cellular and neuronal elements of the adrenal gland. This study may act as a new direction for treatment of adrenal insufficiency.

A Histological, Histochemical and Ultrastructural Study on the Fundic Regionof the Stomach of Nile Catfish (Clarias gariepinus)

The present work was carried out on 20 specimens of both sexes of Nile catfish in order to observe the morphological and histological as well as the fine structure of fundic gland region of the stomach. The present study demonstrated the presence of folded mucosa in the fundic region of the stomach and its surface epithelium was lined by simple columnar mucosecretory cells. The lamina propria contained simple tubular branched glands. The fundic glands were made up of oxyntico-peptic cells. The glandular cells were positive to PAS and negative to Alcian blue and showed strong positive activity for acid phosphatase. The electron microscopic examination revealed that the oxyntico-peptic cells contained a dense tubulovesicular system that may participate in hydrochloric acid production, in addition to the extensive presence of mitochondria and rough endoplasmic reticulum. The Golgi complex is involved in the formation of secretory or zymogen granules. Oval to round- shaped enteroendocrine cells were scattered among the glandular and superficial columnar cells, which stained positive to Grimelius stain. The glands were surrounded by collagenous fibers and smooth muscle fibers

Comparative structural organization of skin in red-tail shark (Epalzeorhynchos bicolor) and guppy (Poecilia reticulata).

The surface architecture and histological organization of the skin of two ornamental fish; red-tail shark (Epalzeorhynchos bicolor) and guppy (Poecilia reticulata) were the main focus of this study. The skin of the two species was composed of epidermis, dermis and hypodermis, although the epidermis showed great variations in their components in the two species. The epidermis of red-tail shark was consisted of epidermal cells, mucous goblet cells, serous goblet cells, club cells, rodlet cells and melanocytes. While, the epidermis of guppy was composed of epidermal cells, mucous goblet cells, eosinophilic granular cells, lymphocytes and melanocytes. The skin of red-tail shark included a variety of sense organs as tuberous receptor organs in the head, superficial neuromasts on the lower lips and the head, canal neuromast in the operculum and the head, and taste buds on the lips, operculum, dorsum of the head and lateral regions of the trunk. However, the skin of guppy was characterized by presence of ampullary organ on the dorsal side of the head, superficial neuromasts on the lips and the head, canal neuromast in the operculum and the head, and taste buds on the operculum, dorsum of the head and trunk regions. These structural peculiarities with histochemical features indicate additional physiological role of the skin of the two species, as the mucous goblet cells in the two species contained a considerable amount of glycoconjugates, whereas the other unicellular gland types, the serous goblet cells and club cells in red tail shark were proteinous in nature. The dermis and hypodermis was consisted of connective tissue, mainly collagenous fibers. Scanning electron microscopy indicated presence of fingerprint like- patterns of microridges of the epidermal cells, pores for lateral canal system, openings of mucous cells and taste buds with specific sensory organs in each fish species.

Cellular and stromal elements organization in the liver of grass carp, Ctenopharyngodon idella (Cypriniformes: Cyprinidae)

Fish liver is considered as a key organ that controls various life functions. The cellular and stromal elements of liver of eighteen specimens of adult grass carp were investigated by light- and electron- microscopy and enzyme histochemistry. The liver was formed of two lobes with a long process extended from the right lobe. Serial paraffin section of the liver identified different kinds of vascular- biliary structures as follows: 1) pancreatic-venous-biliary-arteriolar tracts (P-VBAT); 2) venous-biliary-arteriolar tracts, (VBAT); 3) pancreatic-venous-biliary tracts (P-VBT); 4) venous-biliary tracts (VBT); 5) venous-arteriolar tracts (VAT); 6) isolated veins named as venous tracts (VT); 7) isolated bile ducts, named as biliary tracts (BT); 8) biliary-arteriolar tracts (BAT); 9) pancreatic-biliary tracts (P-BT); 10) pancreatic- venous tracts (P-VT). Macrophages aggregates were associated with VBT and P-BT. The hepatic parenchyma was consisted of many populations of cells. Histochemically, the hepatocytes were strongly reacted with PAS, and Bests carmine. Moreover, strong staining patterns for acid phosphatase, ATPase, and alkaline phosphatase were demonstrated in hepatocytes. The hepatic satellate (Ito) cells were observed in the space of Disse and between hepatocytes. Rodlet cells and eosinophilic granular/ mast cells were encountered in the liver of grass carp. The sinusoids were lined by fenestrated endothelial cells and Kupffer cells. Moreover, dendritic-like cells were demonstrated in the sinusoids and perisinusoidal connective tissue. The biliary duct system was constituted of bile canaliculi, ductules, and bile ducts. Telocytes with their characteristics telopodes were located around bile ducts. The current findings are offering fundamental data on histology of grass carp liver.