Comparative histomorphology of the Mauthner cells in some freshwater teleosts

The histomorphological observations are made on the Mauthner cells in eight species of teleosts belonging to six different families. The cells are better developed in Channa punctatus, Heteropneustes fossilis, Labeo rohita, Danio, malabaricus and Puntius ticto. They are symmetrically situated in Nandus nandus and are found to be absent in Mastocembalus armatus. Their position, shape and size vary in different species. The axon cap is well developed in Channa punctatus, Heteropneustes fossilis and carps. The cell body sends lateral and ventral dendrites besides several small dendrites. The lateral dendrite emerges through the axon cap, turns dorsolateral and becomes myelinated to form Mauthner axon. The Mauthner axon extends in the spinal region upto the caudal peduncle and forms synapses with the spinal motoneurons of the front column. There are numerous synapses and end bulbs from the vestibular fibres and VIIIth nerve distributed on the perikaryan of the Mauthner cell body. It is suggested that the Mauthner cells are comparatively well developed in those species in which the tail fin is better utilized for swimming.