Neurosecretion of brain and thoracic ganglion and its relation to reproduction in the female crab,Potamon koolooense (Rathbun)
The gonadotropic function of the neurosecretory system of brain and thoracic ganglion in the adult female crab,Potamon koolooense is examined. The type A-cells of brain and thoracic ganglion display marked annual cyclic changes of synthesis and release of cytoplasmic material in association with the ovarian cycle. Administration of the thoracic ganglion extract during early oogenesis induced oocyte growth and precocious vitellogenesis, with an increase in the ovarian weight or gonad index and oocyte diameter. However, the brain extract injection did not produce marked changes in the immature ovary. The results suggest that the ovarian activity, particularly growth and vitellogenesis, depend on the neurosecretion of the thoracic ganglion, especially on the activity of A-cells. The neurosecretion of A-cells of the brain seems to be involved in the process of mating and ovulation.