21G 



HYPOPHYSIS AND GONADOTROPHIC HORMONES 



cm 



•m 

















N 



1* - 7-^l»,*!»^» « . 



cm 



-@r 



/ 



fjdUms. 



~^^. 





nti 



Fig. 3.27. Electron micrograph (if , I .-((imn iinn, il,, nm i lor ])ituitary of :i imini.-il 

 adult female rat showing an acidojihil iti ihe i\ pu uJneh j> ihuught to be re.^pun.^iMc for the 

 production of mammotrophic hormone (Hedinger and Farquhar, 1957; Farquhar and Rine- 

 hart, 1954a). The nucleus (A^^) and the cell membrane (cm) of the mammotroph are shown. 



These cells are typically found alone, rather than in groups, in the normal, nonlactating 

 animal. Their most distinctive feature in electron micrographs is their cytoplasmic content 

 of very large, dense secretory granules (gr) with a maximal diameter of 600 to 900 m/i. In this 

 cell they are predominantly found grouped to the left of the nucleus (N). The granules ap- 

 pear very dense and do not show evidence of internal structure. Their appearance is in con- 

 trast to that of the mitochondria (m) which are usually more elongated, much less dense, and 

 show clear internal structure which is difficult to see in detail at this relatively low magnifica- 

 tion. 



Tubular and cisternal (elongated) profiles of the endoplasmic reticulum (er) as well as 

 vacuoles of the Golgi complex (G) may also be identified in the cytoplasm. The two areas 

 marked A represent segments of the cytoplasm of two adjacent acidophils of the type 

 which are presumed to be responsible for the production of growth hormone. The smaller 

 size of the secretory granules distinguishes these cells from the mammotrophic acidophil. 



A portion of the nucleus of a thyrotroph (T) is seen to the right. Cytoplasmic processes of 

 this cell extend out from the nucleus to encircle partially the mammotroph. The cell may be 

 identified as a thyrotroph on the basis of its angular shape and content of very small secretory 

 granules. 



In the lactating animal acidophils of this type with large secretory granules are very 

 numerous and can be seen in virtually every field (Hedinger and Farquhar, 1957). X 11,700. 



