ABSTRACT
Gonad stimulating substance (GSS) is a peptide extractable from radial nerves that stimulates ovarian follicle cells to release 1-methyladenine, which in turn induces oocyte maturation and spawning in seastars. Although a great deal is known about this neuroendocrine phenomenon, the precise location of GSS in the radial nerve cord, and the pathway by which GSS is transported to the ovary remain unclear. Here we report immuno-histochemical localization of GSS to the nerihemal epithelium of the radial nerve cord in Pycnopodia helianthoides. The location of GSS appears to correspond to axons containing numerous 100 nm diameter, electron-dense vesicles. We propose that GSS is released into the radial hemal sinus and transported to the ovary within the hemal system.
