Hypothalamo-neurosecretory system of the marine teleost, Decapterus russelli (Ruppell 1830)

Hypothalamo-neurosecretory system of Decapterus russelli (Family Carangidae) mainly comprised nucleus preopticus (NPO), nucleus lateralis tuberis (NLT) and their axonal tracts. NPO was a paired structure located on either side of the third ventricle slightly above and anterior to the optic chiasma. It was highly vascularized with broad anterior and narrow posterior ends. NPO was divisible into a dorsal pars magnocellularis (PMC) comprising larger neurosecretory cells and ventral pars parvocellularis (PPC) with smaller neuronal cells. Acid fuchsin-positive colloid-like neurosecretory droplets of various sizes were encountered in the NPO and NLT of the scad. Neurons of PMC and PPC contributed beaded axons to form the neurohypophysial tract. A few small herring bodies (HB) were also seen in the anterior neurohypophysis (ANH).