[Human lingual organogenesis: histochemical and ultrastructural aspects]

The structural, ultrastructural and histochemical studies of tongues of human fetuses of 8 to 32 weeks development, were carried out to evaluate the possible chronologic coincidences in the differentiation process of the histologic components during organogenesis. From week 8 to 32, the epithelium increased its cellular layers, becoming flat, stratified, with parakeratinized areas, abundant desmosomes, tonofilaments and scarse intracellular granules. Chorionic fibers increased concomitantly, decreasing mucosubstances. Rudimentary papillae appeared on the dorsal surface of the tongue at 8 weeks, the fungiform ones being evident at 12 weeks. Glycoproteins in the basament layer became evident along with the papillary differentiation, reaching their definitive form at 20 weeks. Myoblasts were observed at 20 weeks. Glandular buds were noticed at the early age studied as were rich in glycogen inclusions and transversal striations were at 20 weeks the structural and ultrastructural differentiated acini, with PAS positive, metachromatic and alcianophilic secretions. The cytochemical changes observed are indicative of the cell differentiation process and tissues participating in the histogenesis present a similar rhythm of differentiation and growth.