HYPOPHYSEAL MORPHOLOGY 



179 



are active during pregnancy and lactation 

 are cat (Dawson, 1946; Herlant and Raca- 

 dot, 1957), rabbit (Pearse, 1951), monkey 

 (Dawson, 1948), and bat (Herlant, 1956a). 



In the rabbit the discharge of luteinizing 

 hormone which causes ovulation occurs 

 within 1 hour after coitus. Pearse (1951) 

 found at this time a discharge of granules 

 from basophil cells which presumably were 

 secreting luteinizing hormone. For the first 

 3 to 4 hours after coitus the carminophil 

 cells were accumulating granules ; thereafter 

 there was a slow discharge of granulation 

 during the next 10 hours. These changes in 

 the carminophil cell are consistent with a 

 luteotrophic function for the secretion of 

 these cells. 



The responses of the carminophil cell of 

 the cat (Dawson, 1946) are similar to those 

 of the rabbit. They are consistent with an 

 accumulation of granules at estrus and for 

 a time after mating, with a secretion with 

 luteotrophic action immediately after ovu- 

 lation, with a further accumulation of gran- 

 ules during the later stages of pregnancy 

 when a luteotrophic action by the hypophy- 

 sis is not necessary, and with a phase of 

 strong secretory activity with a lactogenic 

 action, beginning at parturition and con- 

 tinuing for the first 3 weeks of lactation. It 

 should be noted here that Herlant and 

 Racadot (1957), while confirming the luteo- 

 trophic action of carminophil cell secretion, 

 consider that in the cat this cell secretes 

 the luteinizing hormone. They relate lacto- 

 genesis to the secretion of a hormone, pre- 

 sumably prolactin, by chromophobe cells, 

 which are rich in cytoplasmic ribonucleic 

 acid. I am inclined to think, from the simi- 

 larity in the responses of carminophil cells 

 in cat and rabbit, that they serve the same 

 function in both species, but admit the ne- 

 cessity for further investigation in the cat. 



Because of its unusual breeding cycle, the 

 bat (Herlant, 1956a) presents peculiar ad- 

 vantages for the correlation of specific cell 

 types with specific secretion. In this species 

 the carminophil cells show two phases of 

 secretory activity during the breeding cycle. 

 The first phase begins at the time of ovula- 

 tion and terminates during the latter half of 

 pregnancy; the second phase begins a little 

 before parturition and continues throughout 

 lactation. In animals wliich do not lactate. 



these cells involute rapidly after parturition. 

 The responses indicate secretion of prolactin 

 with luteotrophic and lactogenic actions at 

 appropriate times. 



In two mammalian species the carmino- 

 phil cell is the stable type, and the orangeo- 

 phil the reactive type during the breeding 

 cycle. These are: (1) Human hypophysis. 

 The orangeophil cells are active during 

 pregnancy and contain orangeophil granula- 

 tion towards the end of pregnancy. These 

 cells have been called pregnancy cells by 

 Erdheim and Stumme (1909). Romeis 

 (1940) calls the orangeophil cells seen in 

 small numbers in the hypophyses of males 

 and nonpregnant females "e"-cells, and the 

 numerous orangeophil cells seen in late 

 pregnancy "7/"-cells. Any differences be- 

 tween the two are presumably due to dif- 

 ferent states of activity. The granules of 

 both show the same staining reactions, and 

 only one type of orangeophil cell is seen in 

 any one hypophysis. (2) The rat (Lacour, 

 1950; Dawson, 1954a). Purves and Gries- 

 bach (1952) inferred the separate existence 

 of somatotroi)hin and prolactin-secreting 

 cells from the differential effects of estrogen 

 and a deficiency of thyroxine on the acido- 

 phil cell population, but could not achieve 

 a tinctorial differentiation. The orangeophil 

 staining achieved by Lacour was not repro- 

 ducible. Dawson's (1954a) modification of 

 the azan stain has usually given an orangeo- 

 phil reaction in the active-looking acidophils 

 of the pregnant rat pituitary, and in the sim- 

 ilar cells appearing after estrogen adminis- 

 tration but the staining is sometimes un- 

 successful. Obviously the staining affinities 

 of the two types of granulation in the rat 

 are very similar. 



In all tliese species except the rat, the 

 reactive acidophil type, whether it be the 

 carminophil cell in the cat, rabbit, mon- 

 key or bat, oi- the orangeophil cell in the 

 human hypophysis (Floderus, 1949), has 

 a different distribution from that of the 

 nonreactive type, and the marked increase 

 in the number of visible cells at certain 

 times is due to the appearance of granules 

 in previously nongranulated, and, there- 

 fore, chromophobic cells. In the rat the 

 orangeophil staining appears to be the re- 

 sult of a change in the nature of the gran- 

 ules in a jiroportion of the acidophils, which 



