NEURO-ENDOCRINE SYSTEMS OF INVERTEBRATES 



453 



Sexual Development in Octopus 



Inhibitory nerves also are important in the sexual endocrinology of Octopus. 

 In this animal. Wells and Wells (1959), showed that a hormone released by 

 the optic glands promotes sexual maturity in both males and females. In 

 young octopuses the optic gland is inhibited by a nerve that originates in the 

 subpedunculate/dorsal basal region of the brain. Premature release of the optic 

 gland hormone can be experimentally elicited by cutting the inhibitory nerve 

 leading to the optic glands, by destroying the appropriate region of the brain, 

 or by cutting the optic nerves (Fig. 5). The last observation suggests that the 

 inhibitory center in the brain is normally driven by visual stimuh; perhaps it 

 is the diurnal light-dark cycle that is important. 



OPTIC NERVE 



"CENTER" IN SUBPEDUNCULATE / 

 BASAL REGION OF THE BRAIN 



OPTIC GLANDS 



optic gland 

 hormone 



IT 



GONADS 



(promotes sexuol moturity) 



Fig. 5. A diagrammatic summary of the control of sexual development in Octopus 

 (Wells and Wells, 1959). 



> excitatory nerve; > inhibitory nerve; 



y excitatory hormone. 



INHIBITORY HORMONES FROM NEUROSECRETORY 



CELLS 



Crustacean Molting 



Early in this century, Zeleny (1905) found that reinoving the eyestalks 

 from a crustacean may cause a shortening of the interval between molts. 

 The endocrine mechanism controlling crustacean molting has been worked 

 out by the efforts of many workers (summarized by Knowles and CarHsle, 

 1956; Carhsle and Knowles, 1959). Hormones are produced in the cell bodies 

 of neurosecretory cells in the central nervous system and in the ganglionic X 

 organ of the eyestalk. The hormones are transported down the axons and are 



