Localization and identification of crustacean hyperglycemic hormone producing neurosecretory cells in the eyestalk of blue swimmer crab,Portunus pelagicus

This study intensely focuses on to the localization and identification of crustacean hyperglycemic hormone (CHH) producing neurosecretory cells in the eyestalk of the blue swimmer crab Portunus pelagicus. Anti‐Carcinus maenas‐CHH was used to identify the location of CHH neurosecretory cells by immunohistochemistry. Ten pairs of eyestalks were collected from intact adult intermoult female crab and fixed in Bouin's fixative. Eyestalks were serially sectioned and stained with chrome‐hematoxylin‐phloxine stain. Histological studies show the presence of different types of neurosecretory cells namely A (multipolar), B (tripolar), C (bipolar), D (unipolar), E (oval), and F (spherical) in the medulla interna, externa, and terminalis regions based on their size, shape, and tinctorial properties. The neurohemal organ, sinus gland (SG) was observed laterally between medulla interna and terminalis regions. Immunohistochemical studies showed the presence of distinct CHH‐like immunoreactivity in the optic ganglia. Divergent group of neurosecretory cells with varying degree of immunoreactivity with Anti‐Carcinus maenas‐CHH (low, moderate, and intense reactivity) were identified in medulla terminalis, medulla interna, medulla externa, and sinus gland. The present study maps the various types of neurosecretory cells in the optic ganglia and also shows the presence of CHH‐like immunoreactivity in various regions of optic ganglia in P. pelagicus. The presence of these unique neurosecretory cell types with larger cell diameter in medulla terminalis, a region that bears the neurosecretory cell bodies, suggest high secretory activity.