THE ULTRASTRUCTURE AND IMMUNOHISTOCHEMISTRY OF THE LARYNGEAL MUCOSA OF RANA-PEREZI (AMPHIBIA, ANURA)

The ultrastructure of the laryngeal epithelium in the anuran Rana pere zi is investigated by means of transmission and scanning electron micr oscopy. Moreover, an immunocytochemical study is carried out in order to identify the presence of interspersed neuroendocrine cells (NEC). B y scanning electron microscopy, the epithelium consists of secretory c ells, which bear short, luminal microvilli, and scarce ciliated cells. In the posterior chamber of the larynx, glands which are made by thes e cells are open. By means of transmission electron microscopy, secret ory, basal, and endocrine cells are distinguished into the laryngeal e pithelium. The secretory cells also constitute the mucosal glands and show different types of granules. The first cellular type shows differ ent kinds of secretory granules. Mainly in the glands, the type of gra nule which is the most abundant is very similar to that of the lamella r bodies present in the lung type II pneumocytes. The NEC bear dense c ore granules (125 nm diameter). Intraepithelial nerves are also identi fied in the epithelium. By immunocytochemistry, polypeptide 7B2; and b ombesin-like cells are also observed in the epithelium, and PHI (pepti de histidine-isoleucine) and CGRP (calcitonin gene-related peptide)-li ke nerves are seen in the subepithelial region. The present findings s how 1) that the laryngeal epithelium of this anuran is different from that of the urodeles which have been studied till today whereas 2) it is similar to that of some reptilian orders, and 3) it seems to have a secretion which is rich in phospholipids, and, consequently, the hypo thesis of a close relationship between the secretory cells of the airw ays and of the lung can be made.