174 



HYPOPHYSIS AXD GOXADOTROPHIC HORMONES 



greatly influences the proportionate count 

 obtained from the examination of thin sec- 

 tions. The larger cells not only show a 

 greater area of cross section in the sections 

 in which they appear, but they also appear 

 more frecjuently owing to their greater ex- 

 tension in the direction perpendicular to the 

 plane of section. The third effect, which is 

 also related to the size of the cell as well as 

 to its granule content, is the ease of recogni- 

 tion. When the cytoplasm is scanty the true 

 nature of the cell may be missed and it may 

 be classed as a chromophobe, whereas with 

 equal granule density but with an increased 

 width of cytoplasm it would be classed as a 

 chromophil. These three effects are responsi- 

 ble for most of the variations in cell propor- 

 tions reported in experimental studies of the 

 |)ars distalis. 



It should be noted here that, although 

 marked variations in apparent cell pro])or- 

 tions occur in some species, the hypophyses 

 of other species are remarkably uniform in 

 appearance despite extreme variation in 

 secretory function. Thus the bovine hy- 

 pophysis shows little change in response to 

 thyroxine deficiency, thyroxine administra- 

 tion, castration, or administration of sex 

 hormones. The tendency for experimental 

 work to be concentrated on those species in 

 which functional changes are accompanied 

 by marked cytologic changes has obscured 

 the fact that such obvious cytologic changes 

 are not a necessary accomjianiment to 

 changes in a secretion rate. 



VII. The Acidophil Cell Class 



A. ACroOPHIL GRANULES 



Acidojihil granules consist of a membrane 

 (enclosing solid contents. The presence of the 

 membrane has been demonstrated by elec- 

 tron microscopy (Farquhar and Wellings, 

 1957). The contents include an insoluble 

 protein, phospholipid, and hormones. 



In size acidophil granules range from 0.1 

 to about 1.0 jx. In species where two types of 

 acidophil cells can be seen, it is usual for the 

 granules in one type to have a larger aver- 

 age size than those in the other. In species 

 with large granules, the fact that tliere is a 

 variation of size in the granules within in- 

 dividual cells can be determined with the 

 light microscope. The granule size varies 



with the species, being relatively^ large in 

 man, dogs, and cats, but fine in guinea pigs, 

 mice, and sheep. 



The acidophil granules are highly refrac- 

 tile in the fresh state. In living cells, under 

 dark-ground examination, they are seen to 

 be in constant rapid motion and show a re- 

 fractility and luminosity greater than that 

 of any element in basophil or chromophil 

 cells. Their high refractility is a conse- 

 quence of their solid nature. In typical 

 acidophil cells a high concentration of gran- 

 ules is present in the cytoplasm, and this 

 confers on acidophil-containing areas an 

 opacity which enables them to be distin- 

 guished in the fresh state from zones in 

 which acidophil cells are absent (Smith and 

 Smith, 1923b). 



In rats, almost total degranulation of the 

 acidophil cells follows complete thyroxine 

 deficiency, and in such hypophyses the nor- 

 mal opaque appearance of the anterior lobe 

 changes to the translucent semitransparent 

 api)earance normally seen in the acitlophil- 

 free areas of the bovine hypophysis (Purves 

 and Griesbach, 1946). 



Acidophil granules are quite different 

 from mitochondria. Specific staining meth- 

 ods for the demonstration of mitochondria 

 leave the granules unstained (Severinghaus, 

 1932; 1939). When what may be termed 

 ordinary methods of fixation and staining 

 are used, the staining reactions of mito- 

 chondria and acidophil granules are similar. 



The acidophil granules, like mitochon- 

 dria, are readily released when the cells are 

 disrujited in water, saline solutions, or su- 

 crose solutions. In suspension they have the 

 appearance of spherical highly refractile 

 bodies of varying size. They have a higher 

 density than any other element, but sedi- 

 ment more slowly than nuclei and erythro- 

 cytes because of their smaller size. On pro- 

 longed centrifugation acidophil granules 

 make their way through the layer of nuclei 

 and erythrocytes and api)car on the bottom 

 of the centrifuge tube. Tiiey differ from 

 mitochondria in not swelling up and disin- 

 tegrating in saline solutions or distilled wa- 

 ter, and in not collai)sing on drying. 



H. L1I>()1I) COX'l'K.N r OK A('n)()PHlL GRANULES 



The acidophil granules isolated by cen- 

 trifugation (Herlant, 1952a) are positively 



