714 



E. V. COWDRY 



philic granules. The chromophobe, or clear cells, are also called chief, or 

 principal ce^ls and reserve cells (Addison(a)). According to Tilney(a,), 

 they are in reality faintly basophilic. We have then three cell types; (a) 

 acidophil, (b) basophil and (c) chief cells. It is easy, however, to find ap- 

 parent transitions between them. The basophil and acidophil varieties are 

 usually considered to be descendents or differentiations of the chief cells, 

 but their genetic and functional relations to each other are not at all well 

 understood. At present we do not know whether both of them have 

 definite and specific functions to perform, or whether they represent 

 stages in a single type of activity. The chief cells are distributed fairly 



Fig. G. The same hypophysis area containing for the most part basophil cells. 



evenly throughout the anterior lobe, while the acidophil cells are usually 

 most abundant in its posterior part. The chief cells (c) are often sur- 

 rounded by the basophil (b) and acidophil (a) varieties, so that the 

 latter are brought into close association with the capillaries (Fig. 6). 



Cytology. The structure of the cells has not been very carefully 

 worked out. It is not clear whether they possess a definite secretory 

 polarity in which the capillaries take the place of the usual gland ducts; 

 but tho heaping np of granules near the blood vessels, illustrated in Fig. 

 5, would scorn to indicate that this may be the case. From birth onward 

 most of tho cells contain a small number of fat droplets which stain with 

 Sudan III and blacken with osmic acid. As in other tissues, the fat in- 

 creases with old age. The nuclei of the different cells are similar, except 

 perhaps for slight differences in size. The mitochondria are well known 



