Ultrastructure of an electroreceptor (mormyromast) in a mormyrid fish, Gnathonemus petersii. II.

Light and electron microscopic observations on the type B organ (mormyromast) of the lateral line complex of mormyrids reveal the existence of two types of sensory cells each with distinct separate innervation. The type A cell is specific for this organ whereas the type B cell is almost identical with that of the tuberous organs of mormyrids. The type A cells are located at the base of an intradermal jelly sphere. The type B cells are found within a separate sensory chamber connected to the jelly sphere with a small duct. The type B censory cells are attached to a highly differentiated accessory platform in which three types of accessory cells can be distinguished. The morphological data suggest that the type B organ can provide, by two channels, sensory informations concerned with the same external event, i.e., can detect two different parameters of the same external stimulus.