CYTOLOGY AND POLYSACCHARIDE CYTOCHEMISTRY OF THE GILL OF THE AMERICAN EEL, ANGUILLA ROSTRATA

¹ Department of Biology, Trenton State College, Trenton, New Jersey, 08625

Gills of the American eel were found to be morphologically similar to those of other members of the Anguilla species, and to teleosts in general. Gill filaments contain cartilagenous gill rays rich in polysulfates, and stain intensely in PAS and Alcian blue pH 0.5.

Pillar cells delimit blood spaces within secondary lamellae; they were found to be covered by a thin connective tissue supporting a single-layered epithelium in early juvenile animals and a two cell, layered epithelium in adult eels. In the latter, nuclei of the outer layer were much larger and not as densely stained as those of the inner epithelial cells, whose nuclei appeared flattened over pillar-cell bodies.

Basement membranes supporting epithelia of secondary lamellae and gill filaments exhibited heavy concentrations of sulfate groups shown by reactions in Alcian blue pH 0.5 and Alcian blue pH 5.7 with high concentrations of MgCl₂.

Chloride cells were found in the interlamellar epithelium, especially surrounding afferent lamellar arteries. They had a granular, eosinophilic cytoplasm with carbohydrate polycarboxylates concentrated in distal portions of cells; nuclei had a prominent, centrally-situated nucleolus surrounded by small chromatin masses.

Results of cytochemical tests for all cell types were reported, and information correlated to previous findings on eel gills in particular, and teleost gills in general.