Ultrastructure and histochemical aspects of the oropharyngeal epithelium of Siren intermedia Le Conte.
The present electron microscopical and histochemical study of the oropharyngeal epithelium (OEPI) in Siren intermedia describes its various differentiated and developing cell types and cell contents. The OEPI is multilayered; it consists of a basal layer, a middle cell layer and a pavement layer. Three cell types are found in the pavement layer: pavement cells (PC), goblet cells (GC), and mitochondria-rich cells (MRC). These originate from basal cells and mature in the middle cell layer. The MRC is equipped with a tubule system that seems to be responsible for gaseous exchange. MRC and GC probably appear only in the caudal portions of the oropharynx. Electron microscopically, the goblet cell type appears uniform, except for the production of secretory granules; rostrad, these are largely PAS-positive and occipitad alcianophilic. The production of mucin granules is lower in the PC, where they accumulate as loose aggregations in the cell apex. Their contents react strongly to alcian blue. Only electron-lucent (loose) mucosubstances are exocytosed; they form the apically-situated acidic mucous coat of the PC. The possible osmoregulatory function of these mucins is discussed in relation to the model suggested by Kirschner (1982, in Gomme 1984).
Clemen
G
G
Institut für Spezielle Zoologie und Vergleichende Embryologie, Universität Münster, Deutschland.
Opolka
A
A
D000818:Animals; D004848:Epithelium / Q000648:ultrastructure; D005260:Female; D006651:Histocytochemistry; D008854:Microscopy, Electron; D009061:Mouth Mucosa / Q000648:ultrastructure*; D010614:Pharynx / Q000648:ultrastructure*; D014562:Caudata / Q000033:anatomy & histology*