New formation of sensory cells in the tuberous organ (Electroreceptor) of Brienomyrus niger (Mormyridae) induced by transection of afferent nerve.

The tuberous organs-cutaneous electroreceptors of the mormyrid fish Brienomyrus niger-were examined, with the light and electron microscope, after sectioning of the afferent nerve of the lateral line. Transection of the afferent nerve leads to the concomitant complete degeneration of all sensory cells, and to a differentiation of new sensory cells from accessory cells, which constitute the platform. Ultrastructural examination of the newly formed sensory cells shows that within a few days these gain the characteristics of normal sensory cells. The rapidly growing cytoplasm is enclosed in a folded membrane; the foldings develop typical dense microvilli. At the same time, in spite of lack of innervation, synaptic bars surrounded by vesicles differentiate in the cytoplasm; these are opposed to the basal cell membrane which is attached to the accessory cell platform. The newly formed sensory cells never reach the size of normally developed sensory cells. Their existence is transitory, for they degenerate, together with the sensory cells, one month after de-afferentiation.