Prenatal development of human palatine glands: a structural and cytochemical study

The histogenesis of the salivary glands was structurally and cytochemically studied in human embryos and fetuses during the period of 8 to 32 weeks of intrauterine life. Glandular buds appeared at about 12 weeks of embryonic development. The rounded distal ends of the epithelial cords and neighbouring mesenchyma showed small and abundant PAS positive and alcianophilic granules. At age 14 weeks the secretory end pieces and the duct system were seen at different morphologic and structural stages of a differentiation. Mucous acini with scanty mixed acini predominated and serous acini appeared occasionally. From 20 to 24 weeks the mucous acini stained with toluidine blue featured different degrees of metachromasia even in the case of cells of the same acinus. In the ducts it was also possible to identify metachromatic cells intermingled with basophilic cells in the epithelial coat. These findings suggest that the palatine glands present typical histophysiological material from 14 to 20 weeks. The presence of PAS positive, alcianophilic and metachromatic secretory substance in the acinar lumen and the luminal content of ducts suggests that mucin secretion begins during intrauterine life.