THE PITUITARY BODY 



able to produce oestrus by injecting potent cortical adrenal 

 extract into adult hypophysectomized female rats. 



3. The epiphysis. — Despite Engel's statement to the con- 

 trary (review, 1936), there is not yet satisfactory evidence 

 that pineal secretion antagonizes the gonadotropic secretion 

 of the pars glandularis. Recent observations are those of 

 Fleischmann and Goldhammer (1936), Tarkhan (1937), and 

 Wade (1937). Wade also used prolan and pregnant-mare 

 serum as gonadotropic substances. 



4. The lactogenic hormone of the anterior pituitary .^^^ ^' — 

 Lactogenic extracts of the pars glandularis, injected into fe- 

 male rats, may cause a prolonged period of dioestrus (Dresel, 

 1935). Similar results were obtained by Nathanson, Fevold, 

 and Jennison (1937) both with pituitary extract and with an 

 extract of the urine of lactating women. They suggest that 

 luteinizing hormone rather than lactogenic hormone is re- 

 sponsible for the effect. ^According to Engelhart (1936), the 

 lactogenic hormone brings about extensive luteinization of 

 the rabbit's ovary. However, not all his extracts were free of 

 gonadotropic hormone. Lahr and Riddle (1936) injected 

 lactogenic extract into rats and caused a temporary suppres- 

 sion of oestrous cycles in adult females. Large ovaries con- 

 taining corpora lutea were present after 8-12 days' treatment. 

 The authors doubted that progesterone-secretion was respon- 

 sible for the disappearance of oestrous cycles and suggested 

 that either an alteration of ovarian function or an interfer- 

 ence with the liberation of follicle-stimulating hormone ac- 

 counted for the change produced. Desclin and Gregoire 

 (1937) transplanted ovaries to the kidneys of female rats 

 spayed a few days postpartum. Lactation was permitted to 

 continue in half of the group. A comparison of the ovaries 

 of the lactating and nonlactating groups 15 days later led the 



58 Leblond and Nelson (1936) concluded that the maternal instinct depends 

 neither on lactation nor on internal secretions of the anterior pituitary, although 

 these may reinforce or reduce manifestations of the instinct. 



59 See also chap. v. 



I 98] 



