Histomorphogenesis of sublingual salivary gland of Indian sheep

The primordial anlage of sublingual gland was first noticed as a solid epithelial bud from oral epithelium at the 24^th day of foetal development. The terminal buds were arranged in the form of clusters with undifferentiated epithelial cells and terminated in a bulb-like structure in the 30-day-old sheep foetus. On the 37^th day, lumenization and branching of the main cord was noticed. The primary septa were observed from the 55^th day onwards which resulted in the formation of lobulation on the 60^th day. The capsule formation was initiated by aggregation of mesenchymal tissue on the 63^rd day. On the 100^th day, terminal tubules differentiated to form secretory end pieces. Tubular portions formed intercalated and striated ducts. Predominantly mucous type of acinar cells was seen from the 110^th day onwards with myoepithelial cells. The number of lobules increased with increase in parenchyma from 130^th day onwards. Micrometrical studies revealed that the mean diameter of acini, intercalated, striated and large ducts was increased with advancement of age and significant differences were observed between groups. Localization of acidic and neutral mucopolysaccharides were observed in mucous and goblet cells. Fine lipid droplets were observed in intralobular and interlobular connective tissue however, phospholipids were observed in cell membrane of acini and ducts. The current investigation provides microstructural standards for the organogenesis of the sublingual gland of miniature sheep and can lay the foundation for further studies in the morphological investigation of salivary gland development.