PHOTOPHORES OF PORICHTHYS NOTATUS - ULTRASTRUCTURE OF INNERVATION

Photophores in Porichthys notatus are bioluminescent organs composed of a lens, photogenic tissue, and an underlying reflector. Nerves penetrate through the reflector and branch, free of their Schwann cells, among the photogenic tissue elements. The tortuous pathways of axons have been followed by electron microscopical serial sections. After giving off occasional terminal branches, the axons continue into pockets of connective tissue which penetrate among the photogenic, supportive, and lens cells. There they form tuft‐like clusters of nerve endings, some of which contain dense‐cored vesicles. None of these endings was seen to penetrate the basal lamina and make direct intercellular contact with either a supportive cell or a photogenic cell. From these observations, it is concluded that the nerves end outside of the basal lamina surrounding photogenic, supportive, and lens cells. Adhesion sites, which may indicate chemical synaptic contact, were occasionally observed among these neural components. The photophores of the California Porichthys notatus often bioluminesce following intraperitoneal injection of the fish with epinephrine. It therefore appears from experimental, anatomical and fine structural evidence, that these luminescent organs are innervated and controlled by the sympathetic nervous system. Copyright © 1969 Wiley‐Liss, Inc.