Previously, the distribution of myoepithelial cells (mecs) in the salivary glands was studied by both immunohistochemistry, and transmission electron microscopy; however, little was elucidated concerning their morphological features, especially in goats. This study was performed to investigate the correlation between the cytoarchitecture of the mecs in goat major salivary glands (parotid, mandibular, and sublingual glands) and the nature of the saliva secretion. The cytoarchitectural features of the mecs were examined by scanning and transmission electron microscopy as well as immunohistochemically. The secretory endpieces in the parotid gland are of the pure serous type, but in both the mandibular and sublingual glands they are of the mixed type. In all studied glands, the intercalated ducts were covered by mecs which, unlike the large stellate cells that surrounded the secretory endpieces, were spindle-shaped with few cytoplasmic processes. Interestingly, the mecs were found to bulge on the basal surfaces of the serous acini and intercalated ducts in all glands and to be in close contact to the seromucous tubules surface in the mandibular and sublingual glands forming a continuous network around it. In conclusion, the differences in the degree of development of the mecs as well as the number of their cytoplasmic processes may be correlated with the nature of the secretion and the number of the secretory granules. Thus these observations may have some relevance in the diagnosis of atrophy and pathogenic conditions of these glands.

| Stannius corpuscles (SC) are unique endocrine gland in the kidney of bony fish. It plays an important role in regulating calcium haemostasis via secretion of hypocalcine (stanniocalcin) hormone. The structure of Stannius corpuscles has been clarified in several fish species; however, little was elucidated concerning that in African catfish (Clarias gariepinus). Therefore, the aim of the current study is to reveal the structural characteristics of SC in African catfish (Clarias gariepinus) among both sexes. Histological and ultrastructural examinations of SC were revealed among both sexes. The SC were paired, oval white colored bodies embedded in the trunk area of posterior kidneys. Histologically, the SC were surrounded by thin connective tissue (C.T) capsule from which many septa were extended dividing the glands into incomplete lobules. The parenchymal cells consist of two types; one with intensely eosinophilic cytoplasm and the other were weakly stained. Interestingly, the proportion of cells was varied among male and female. The female showed significant higher percentage of lightly eosinophilic cells than the intensely stained cells. On the other hand, the predominant cell type in male was the intensely stained one. Transmission electron microscopic observations revealed the presence of two types of cells; predominant type I (electron dense and electron lucent cells) and type II. The former showed more secretory granules than the later. In conclusion, our results revealed sexual differences in the proportion of cells and suggested that the type I could be responsible for hypocalcine hormone secretion. However, further investigations are required to reveal the structure of SC among different seasons.

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Background:The fish pancreas has been reported to be composed of two portions: compact and disseminated. However, little has been elucidated in catfish. The present study describes a unique localization of the disseminated pancreas in African catfish. Methods:The sections were obtained and used for either routine histological examination following staining with haematoxylin and eosin (H & E), periodic acid-Schiff's, or were subjected to immunohistochemical staining for detection of both insulinproducing β cells and glucagon-producing alpha cells.Results: Our investigation showed that the pancreas of catfish consisted of both compact and disseminated portions. The compact pancreas was embedded in the mesenteric adipose tissue between the spleen, stomach and liver. However, the disseminated one showed unique localization in the tunica adventitia of the middle portion of the oesophagus. The pancreas consisted of two portions, exocrine and endocrine. Furthermore, in both types of pancreas, the female showed a significantly higher ratio for the endocrine islet area/pancreatic tissue area than that of the male and also a significantly higher ratio for both insulin-and glucagon-positive area/islet area in the female pancreas (compact and disseminated) than that of the male. In conclusion:The present study provides evidence on a unique localization of the disseminated pancreas in the oesophagus of catfish. Furthermore, we revealed sexrelated difference in the endocrine portion in both pancreatic tissues with more development in the female. The study suggests that sex hormones could be contributed to such sexual dimorphism. However, further investigation is required to compare the degree of development during the spawning and resting seasons. K E Y W O R D Sglucagon-secreting alpha cells, insulin-secreting beta cells, islets of Langerhans, oesophagus, pancreas | 595 KARKIT eT Al.