Immunocytological evidence for the presence of vertebrate FSH- and LH-like substances in the brain and thoracic ganglion of the swimming crab, Portunus trituberculatus

Investigating the distribution of follicle stimulating hormone (FSH) and luteinizing hormone (LH) in the swimming crab, Portunus trituberculatus, helps in the understanding of its reproductive regulation mechanism. This study has detected the location of vertebrate FSH- and LH-like substances in the brain and the thoracic ganglion mass with immunocytochemical techniques. Their immunoreaction is very weak or negative during the immature period and the post-spawning period, while it is stronger in the mature period. Localization of FSH-like immunoreactive cells resembles that of LH-like cells. These immunoreactive cells were observed chiefly in the anterior median cell-cluster of the protocerebrum with stronger immunostaining. There were only a few in the inboard cell-cluster of the olfactory lobe of the deutocerebrum and the posterior cell-cluster of the tritocerebrum. Immunoreactive cells were located in all the three ganglia in the thoracic ganglion mass. These results indicated that substances resembling the vertebrate FSH and LH exist in P. trituberculatus, and their expression has some correlation with the developmental stage of ovaries, thus they might engage in the ovary development and ovulation.