Ultrastructural features and glycogen distribution in the electric organ of the electric ray Torpedo marmorata L.

The ultrastructural topography of glycogen in the electic organ of the fish Torpedo marmorata has been examined following Thiéry's method and the modified osmium tetroxide post-fixation of De Bruijn. Both methods reveal a high concentration of glycogen particles in the nerve terminals, particularly in pedunculate pouches issuing from the nerve endings and bulging into the intersyncytial area. A few sparse positive particles are scattered at random in the Schwann cells and in the cuff cells occasionally encapsulating the myelinated and ummyelinated subsynaptic axons. In the electric cell, glycogen occurs in the form of scattered particles homogenously distributed among all the cytoplasm. The structure and the size of glycogen granules in relation to the detection methods used and to previous parallel investigations are briefly discussed.