STEREOLOGICAL AND IMMUNOHISTOCHEMICAL STUDY OF DEVELOPMENT OF HUMAN FETAL LABIAL SALIVARY-GLANDS AND THEIR S-100 PROTEIN REACTIVITY

Stereological and certain histochemical aspects of fetal growth and de velopment of human labial salivary glands are reported. Stereological analysis showed a highly significant progressive increase in proportio nal gland volume occupied by acini from 27% at 20 weeks to 56% at 38 w eeks (P<0.0001), and a comparable halving of the relative gland volume occupied by connective tissue in the same period (P < 0.0001). Linear regression fitted the data well (r(2) = 0.59 and 0.47 respectively, n = 46). The change in relative volume occupied by ducts or by vascular tissue was small and did not reach significance. S-100 protein reacti vity was demonstrated in the cytoplasm of cells of the labial gland pr imordia from their origin. As gland differentiation progressed, the S- 100 reactivity became localized in basophil acinar cells and in proxim al (intercalated and intralobular), but not in distal, duct cells. A g radual increase in intensity of S-100 protein activity at these sites during salivary gland development was observed. Morphological maturity seems to be complete before 29 weeks but myoepithelial cells could no t be identified with certainty.