220 HYPOPHYSIS AND GONADOTROPHIC HORMONES 



cm 



/ 



N 



N 



t \ ' 



^ cm 



Fig. 3.31. Electron iiiici(j<ii,iiili illu-tiaiiii<> im.hious of sc\cial ( ( IN wlml; uii. 1,,, mix- 

 suggested to be concerned with the formation of adrenocorticotrophic liormone (1^'arquhar, 

 1957). Two large nuclei (iV) and a segment of a third nucleus are shown. 



Such cells are typically found in groups and are arranged around large follicles or smaller 

 ductiles. Some of the follicles are quite large, measuring several microns across and are 

 undoubtedly analogous to so-called "colloid cysts" sometimes seen in the anterior lobe by 

 light microscopy. Other follicles, such as the one illustrated here, are quite small and would 

 probably escape detection by light microscopy. 



The cells which line the follicles or ductiles typically show tiny cytoplasmic projections 

 or microvilli {mv) which pro.ject into the follicular lumina. In this field portions of three 

 cells abut on the follicle and form microvilli which pro,)ect into the lumen. 



The follicular cells characteristically do not contain secretory granules. Furthermore, in the 

 normal animal their cytoplasm appears relatively empty, for organized cytoplasmic structures 

 are sparse. Only a few mitochondria {m), occasionally tubular profiles of the endoplasmic 

 reticulum (er), and basophilic particles {hp) are encountered. 



In terms of their somewhat monotonous regularity, these cells resemble more closely the 

 cells from the intermediate lobe than they do any other type of anterior lobe cell. 



Because of the response of these cells to alterations in adrenal activity and their lack 

 of response to other experimental procedures, it has been tentatively suggested (Farquhar, 

 1957) that these cells are responsible for the formation and/or transport of corticotronhin. 

 X 10,800. 



