Hypothalamo-hypophysial neurosecretory system of the teleost Trichogaster fasciatus (Bloch & Schneider) with a note on it's vascularization.

The hypothalamo-hypophysial neurosecretory (HN) complex of Trichogaster fasciatus is described with the help of in situ staining technique and tissue sections. The neurons of the nucleus preopticus (NPO) give rise to fine neurosecretory axons which form the left and right main tracts. The bulk of the tracts come laterally and enter the middle portion of the neurohypophysis. However, some of them spread out and penetrate the rostral neurohypophysis as well. Hypophysial artery contributes to the formation of primary capillary plexus (PCP) which extends from the subterminal region to the extremity of the anterior neurohypophysis. Structurally, the subterminal region and the anterior neurphoyophysis can be compared to the median eminence (ME) of tetrapods as it is differentiated into ependymal, fibrous and reticular layers. Also, these areas have aboundant neurosecretory and silver positive axons suggesting the possibility of direct transmission of neurohormones into the blood.