Histochemical observations on the gills of Lepidosiren paradoxa (Fitz)
Singh, K.P.; Thakur, R.N.; Singh, B.R.
Folia Morphologica 29(3): 263-268
1981
ISSN/ISBN: 0015-5640 PMID: 7274857 Document Number: 170012
The gills of L. paradoxa are reduced and the epithelial coverage thickened (83.2 .mu.m) due to fusion of the primary filaments and complete lack of the secondary lamellae. The diffusion distance has been considerably enlarged (31.2 .mu.m) but shortened to nearly 1/4 owing to the presence of a large number of intercellular channels in the thickened epidermis. The metabolically active cuboidal epithelial cells which become evident from their nucleo-cytoplasmic ratio (1:2.06) form the outer cellular layer of the gill and are loosely arranged to provide spaces for the intercellular channels for communicating outside. The basement membrane is very thick (16.6 .mu.m) and at certain places follows epithelial invaginations. The outer surface of the gill does not show keratinization, but there is a mobile layer of sulfated mucopolysaccharides which can meet the intrinsic needs of the aquatic or abrasive environment in which the fish lives. Goblet cells, usually lying below the surface layer of the gills, have their apical openings usually directed toward the intercellular spaces into which their secretion products can be discharged and reach the outer surface of the gill. Two types of goblet cells can be recognized: 1 secreting weakly acid polysaccharides and the other secreting strongly sulfated mucopolysaccharides.