ABSTRACT
In this study 30 human embryos from 8 weeks to full term were used. The prenatal development of the human sublingual gland was histologically and histochemically studied through sections stained with Haematoxylin and eosin, PAS and Alcian blue reactions. The gland started its development at the 8th week as a branched column of cells. This denoted the earliest indication of duct system formation. The primordia of the duct system were canalised at the 12th week and became differentiated into intralobular, interlobular and intercalated ducts by 20 weeks. At full term, the lining epithelium of the duct segments was simple columnar in the intralobular, pseudostratified columnar in the interlobular and flat in the intracalated ducts. The secretory unit developed later than the duct system, since the primordia of the acini appeared at 12 weeks. They showed cavitations at 18 weeks and became differentiated into mucous and serous acini by 20 weeks. The mucous acini were more numerous than serous ones, and some of them were capped with serous demilunes. A strong PAS reaction in the primordial cells appeared from the 8th week to full term. The duet cells showed progressive decrease in PAS reaction, while moderate PAS materials within the duct lumen were seen. AB reaction, however, was observed in the mucous acini for the first time at 12 weeks and increased at full term. The serous acini were negative at early stage, while at full term they showed faint reaction. The duct cells were unreactive to AB, though, their lumina showed rective materials from 12 weeks to full term