THE PITUITARY BODY 



differentiated from the primitive undifferentiated (or re- 

 serve?) cells in embryonic life is the oxyphil. In all these 

 mammals, the basophils can be recognized only later; in 

 some, like the dog, basophils cannot be found until after 

 birth. According to Nelson (1930, 1933), the process is re- 

 versed in the pig. The principal chromophil cell in pig em- 

 bryos of 7-10 cm. is the basophil. Oxyphils appear in em- 



FiG. 7. — Photomicrograph of the pars glandularis of the dog. Mallory's stain. 

 X 1,290. fi, basophils; 0, oxyphils; R, reserve cells. 



bryos about i6 cm. long and tend to predominate in embryos 

 of 20 cm. 



The distributio}i of the three types of cells in the pars glandu- 

 laris. — In some mammals like the ox, one part of the pars 

 glandularis (in this case the central part) may be richer in 

 basophils than other parts (Smith, 1923). Soos (1934) be- 

 lieved that the number and distribution of basophils varied 



[14] 



