Special cutaneous receptor organs of fish: VI. Ampullary and tuberous organs of Hypopomus

Abstract

Both ampullary and tuberous special cutaneous receptor organs are present in the gymnotid fish Hypopomus. The ampullary receptor organs are morphologically very much like those of the related genus, Eigenmannia, in organ structure and receptor cell ultrastructure. The tuberous organs are of three types, two of which are restricted to the anterior part of the fishes' body and one to the posterior part. The anterior tuberous organs differ from the single type found in Eigenmannia primarily in synaptic ultrastructure. The posterior tuberous organs differ in having a long canal between the organ capsule and the epidermis, and in having the receptor cells in a compartment that is separated by a continuous cellular cap from the extracellular spaces of the canal and the overlying epidermis.