THE PITUITARY BODY 



the guinea pig, the presence of a gonad, functioning definitely 

 but at a low level, appears not to lessen the gonadotropic 

 potency of the pituitary in comparison with that of gonad- 

 ectomized animals (Lipschiitz, 1936). 



Other observations on the relation of sex to the pitui- 

 tary's content of gonadotropic hormone have attempted to 

 distinguish between the follicle-stimulating and luteinizing 

 hormones. According to Lipschiitz and Del-Pino (1936), man 

 resembles the rat and guinea pig in that (tested in the imma- 

 ture rat) the male pituitary causes more formation of lutein 

 tissue than the female. (The pituitary of women in the first 

 month of pregnancy caused luteinization of the ovaries; in 

 the later months this effect diminished or disappeared.) 

 The opposite view was expressed by Pfeiffer (1936-37), as 

 well as by others, whose experiments were performed in rats. 

 According to this author, the male pituitary is capable of se- 

 creting very little luteinizing hormone. Moreover, Pfeiffer's 

 conclusion appears to be based on a more "physiological" 

 method (the behavior of ovarian grafts as affected by the 

 gonadotropic hormone secreted by the host's pituitary). The 

 conflicting views expressed in recent reports are summarized 

 in Table 2. Some of these results will be considered later 

 when an evaluation will be attempted. Pfeiffer (1936), rely- 

 ing on the effect on ovarian transplants of gonadotropic hor- 

 mone released by the rat's pituitary in situ, concluded that 

 the normal male pituitary secretes follicle-stimulating hor- 

 mone with little or no luteinizing hormone, whereas the fe- 

 male pituitary is "bipotential" — i.e., secretes both hormones. 

 Also he believed that this sexual difference is hormonal rather 

 than genetic and that after puberty the pattern of pituitary 

 secretion is practically fixed; Pfeiffer (1936-37) cites other 

 experiments in support of these views. 



1. Experiments with animals in parabiosis.^^ — No attempt 



^5 Unless there is a statement to the contrary, all the animals used are rats. 

 References to other experiments employing the method of parabiosis will be found 

 both in this chapter and in the Index. 9 refers to a normal female; ^ refers to a 



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