THE PITUITARY BODY 



laris of mammals like the rat at different stages of the 

 oestrous cycle vary greatly. The recent careful study of 

 Wolfe (1935), who used both qualitative and quantitative 

 technics, led him to conclude that in the female rat the pro- 

 portion of none of the cells — disregarding finer qualitative 

 details such as the content of granules — varies at different 

 stages of the oestrous cycle.'" He believed that the only clear- 

 cut cyclic change is in the granules of the basophils. These 

 granules are most numerous in pro-oestrus and rapidly dimin- 

 ish in number during oestrus and metoestrus. Pfeiffer (1937) 

 supplemented his other experiments designed to alter the 

 sexual characteristics of pituitary function in rats (see chap. 

 iii) by anatomical studies. The distribution of cells typical 

 of the male or female pituitary could be produced by trans- 

 planting testes into spayed females or ovaries into castrated 

 males. The anterior pituitary of animals with both ovarian 

 and testicular grafts tended to be of the male type. After 

 puberty and, therefore, after sexual differentiation of the pars 

 glandularis, the distribution of cells could not be altered. 



The alterations in the pituitary accompanying parturition 

 and the onset of lactation have interested several investiga- 

 tors. Collin and Florentin (1935) who used guinea pigs, as 

 well as Weis (1935) who used rats, stated that an unusual and 

 marked predominance of reserve cells is observed at parturi- 

 tion and for about 24 hours later. They beheved that this 

 change is related to the initiation of lactation. Collin and 

 Florentin also concluded that the oxyphil is the more numer- 

 ous chromophil during the first half of pregnancy, whereas 

 the basophil predominates toward the end of pregnancy. 

 Desclin (1936) was interested in the significance of the corpus 

 luteum in maintaining the pituitary's lactation morphology 

 in the rat. He found that the latter persists after ovariec- 

 tomy, provided that the young continue to suckle. If, how- 



'° The proportions of the different cells confirmed Wolfe's previous report. The 

 means and standard deviations were: basophils, 4.1 + 1.3 per cent; oxyphils, 

 34.2 ± 4.3 per cent; reserve cells, 61.8 + 4.4 per cent. 



f 16I 



