148 



KINETIC HORMONES — II 



the hypophysis and the source of ACTH, the naturally induced 

 secretion of ACH is only reduced to one half. 



4.232 Gonads stimulated by gonadotrophic hormones 



Morphogenetic hormones, secreted by the gonads, have a variety 

 of effects related to reproduction, and have been reported from 



500 



400 



cr> 

 O 

 O 



300 



< 

 en 



2 



200 



Saline 



Histamine 



30 

 Minutes 



45 



60 



Fig. 4-11. Effects of injections of saline, epinephrine (adrenaline) 

 and histamine on the ascorbic acid content of the adrenal cortex of 

 rats, in mg/100 g gland (ordinates). The saline causes no change in 

 60 min (abscissae) ; the reduction due to adrenaline and histamine 

 is by then the same, showing the two doses to be equivalent. The 

 effect of histamine is much the more rapid, and must therefore 

 evoke secretion of ACTH directly and not through any inter- 

 mediary action of adrenaline (cf. Fig. 4-10, based on similar 

 experiments). (From Munson and Briggs, 1955). 



many animals, including an unusually wide range of invertebrates 

 as well as vertebrates. So far, it is only in the vertebrates that the 

 secretion of these gonadial hormones is known to be controlled by 

 endocrinokinetic hormones. Like the other hormones of this type 

 in vertebrates these are all secreted from the adenohypophysis ; 

 they are often referred to as gonadotrophins, in common with 



