HISTOLOGICAL STUDY OF THE PAROTID GLAND OF ADULT GOAT
Reda A. Abd Elhamid
Department of Anatomy, Faculty of Medicine, Zagazig University
Background: The salivary glands of mammals exhibited a striking histological, histochemical and ultrastructural diversity. The acini and the striated ducts of the salivary glands are regarded as the principal sites for the formation of saliva. The process of secretion in the ductal cells depends on the presence of electrolytes dependent enzymes that are concentrated in the basal parts of the cells. It is likely that Na+ K-activated ATP-ase plays a direct role in the formation of the primary saliva. Aim of the work: this work aimed to study the structure of the parotid gland of adult goat. Materials and Methods: eight adult healthy goats were used in this study. After anaesthetizing the animals, small pieces of parotid salivary glands were taken and processed for light and electron microscopy examination. Results: The parotid gland was formed of lobules separated by thick septa. The lobules were formed of acini and ducts at variable sites and the acini showed strong PAS reaction. The acini of the parotid gland were lined with cells rich in rough endoplasmic reticulum, mitochondria and secretory granules. The luminal surface of the cells showed numerous microvilli that were continued with each other by intercellular canaliculi containing microvilli. The acini in between the acinar cells and the basal lamina contained microvilli. The intra-lobar (striated) ducts contained many types of ductal epithelial cells, one type appeared with electron lucent cytoplasm containing few cytoplasmic organelles, basally located nuclei and few rounded mitochondria. The other type is electron dense cells containing large sized nuclei, numerous mitochondria, electron dense granules and abundant basal enfolding. The luminal surface of the cells lining the ducts showed projection of long and short microvilli and short and long frondose processes. The cytoplasm of the luminal folds contained many glycogen showed secondary processes from their sides. The cells of the ducts revealed occludens junctions between their sides near their luminal surface. Also, the process of release of secretion of the acinar cells occurred by the apocrine process. Conclusion: The parotid gland acini and ducts showed different types of cells containing large amount of secretory granules and their cell membrane showed modification to increase surface areas of contact and ion transport.