HORMONAL CONTROL 551 



described by Dahlgren (1914) in the spinal cords of Fishes. They were later studied 

 in the hyjDothalamus of Teleosteans by E. Scharrer (1928) and in the eye-stalks of 

 Crustaceans by Hanstrom (1931-34) ; but our present concej^tions of the nature and 

 function of neuro -endocrine conij^lexes within the nervous system date essentially 

 from the work of Berta and Ernst Scharrer (1937-45). It now seems obvious that 

 the secretory activities of the central nervous system or of cells directly derived 

 therefrom exert a considerable influence on the metabolism and activities of many 





"^^J^-i^ 



■ I ' 1 1 'I ■ I 

 lO/t 



Fig. 721. — XEURO-sECKETOiiY Cell. 



From the right nucleus paraventricularis of the rat. The granules of neuro- 

 secretory material are seen in all the neurones and their axons. Note the charac- 

 teristic fusiform enlargements in the axon emerging from the large cell in the upper 

 left corner of the figure. The granule-laden segments seen everywhere are cut 

 portions of the axons of other neurones at a distance from theii- cell bodies (Stuart W. 

 Smith, Amer. J. Anaf., 89, 229). 



species of animals including man. The secretions are elaborated within a large cell- 

 body wherein they appear as granules and colloid-like material which are extruded 

 along the axons, sometimes to be stored in organs in which the enlarged nerve-endings 

 terminate (Fig. 721).^ The latter are gland-like structures which serve as storage- 

 release centres and, since it appears unlikely that the specialization for secretion has 

 eliminated the capacity of these cells to act as conductors, a neuro -secretory cell can 

 presumably trigger the release of its owii accumulated secretion by conducting 

 impulses to its endings at the storage-site. It follows that if it were formed from 

 several completely independent groups of jjarent cells, such a " gland " might well 

 serve as the storage-release centre for several hormones (see Brown, 1944^51 ; Brown, 

 Sandeen and Webb, 1951 ; Brown and Hines, 1952 ; B. Scharrer, 1953 ; and others). 



^ The secretory products are most dramatically shown by staining with the chrome 

 alum-hfcmatoxylin-phloxine technique of Gomori (1941). See Bargmann (1949). 



