Presence of Pseudobranchial Neurosecretory System in Barilius bendelisis : A Paraneuronal Neuroendocrine System

“Diffused neuroendocrine system (DNES)” includes a diversity of paraneuronal cells which are known to be scattered throughout the vertebrate body. They are well known to secrete a plethora of neurochemicals that act in autocrine and/or paracrine mode. Pseudobranchial neurosecretory system is one such DNES. It is found uniformly in all the catfishes and some other groups of non-catfish teleosts. However, it was not found in carps so far. The present investigation is the first time report of the presence of this system in a carp Barilius bendelisis. In catfish, the system is present in association with carotid labyrinth—a chemosensory structure known in fish and amphibians. The carotid labyrinth is a derived structure of pseudobranch. Hence, the revelation of the pseudobranchial neurosecretory system in association with pseudobranch in B. bendelisis has significant evolutionary implications.