Morphology of the pineal organs of Mystus aor (Ham.) and Puntius sophore (Ham.) with special reference to their innervation.

In Puntius sophore and Mystus aor the pineal end-vesicle (EV) has prominent lumen which is in open communication with the third ventricle through the long hollow stalk. In both the species the EV as well as the stalk have all the three component cell types namely sensory epithelial, supportive and nerve cells. The outer segments of the photoreceptor cells gave positive reaction to PAS, alcian blue, aldehyde fuchsin, sudan black, acetic thionin and Heidenhains' iron haematoxylin, but almost negative to toluidine blue. Apart from the Palmgren, Cajal and Golgi, nerve impregnation techniques, the neurons could be identified with the aid of Heidenhains' iron haematoxylin, acetic thionin and toluidine blue. They are arranged in all planes generally in contact with the synaptic pedicles of the sensory epithelial cells. The axons of the neurons present both in EV and stalk contribute to the formation of the pineal tract which courses down the pineal stalk. Rapid Golgi technique is apparently selective as only less number of neurons are impregnated. But with Cajal and Palmgren the intense maze of axons present in the pineal could be demonstrated. In both the species bulk of the pineal tract could be traced into posterior commissure (PC) and subcommissural organ (SCO). However, in P. sophore some projections are seen entering the optic tectum and the ependymal lining of the third ventricle.