HORMONES AND MATING BEHAVIOR 



1201 



substances) before they are incubated, may 

 be advantageous in future studies of the 

 effect of prenatally administered hormones 

 on the behavior disphiyed as adults. In their 

 frankly preliminary communication Pincus 

 and Hopkins noted that raasculinization of 

 the female was not accomplished as easily 

 as feminization of the male. This relation- 

 ship is the reverse of that encountered in 

 mammals and is not unexpected. If it is 

 seen generally in birds, extensive experi- 

 ments will be of more than ordinary inter- 

 est. 



Results from a series of experiments on 

 intact albino rats during the prepubertal 

 period are not suggestive of an organiza- 

 tional action; on the contrary, damaging 

 effects are indicated, but in view of what 

 has been found during the work on the 

 guinea pig, the rat should be restudied. Fe- 

 males injected with androgens or estrogens 

 during the first 10 days after birth experi- 

 enced a permanent impairment of cyclic 

 rei)roductive function. They are described 

 as displaying no sexual behavior (Wilson, 

 Young and Hamilton, 1940; Wilson, Hamil- 

 ton and Young, 1941; Wilson, 1943). The 

 effect could not be attributed solely to gon- 

 adal failure because in neither group could 

 estrus be induced with estrogen and pro- 

 gesterone, even with 10 or more times the 

 quantity of estrogen required to condition 

 normal animals. Treatment of males with 

 androgen induced serious alterations of 

 structure and function accompanied by im- 

 potence, especially when 0.75 to 36.0 mg. of 

 testosterone propionate were given between 

 the day of birth and day 28 (Wilson and 

 Wilson, 1943). Ejaculation was less frequent 

 in the injected animals and the mean num- 

 ber of mountings per test was low. 



In other experiments on immature rats 

 no such damaging action followed the ad- 

 ministration of testosterone propionate into 

 males or of estradiol benzoate into females; 

 instead, the precocious activation of previ- 

 ously organized neuromuscular mechanisms 

 was reported (Stone, 1940; Beach, 1942c). 

 In comparing these results with those ob- 

 tained by Wilson, Young and Hamilton 

 (1940). Wilson, Hamilton and Young 

 (19411. Wilson (1943), and Wilson and 

 Wilson (1943) the circumstance should be 



considered that administration of the hor- 

 mones was not begun by Stone and Beach 

 until day 22 to 26 and day 14, respectively. 

 That the age of the animal at the time of 

 treatment could be crucial has been brought 

 out by Barraclough (1955) and by Doeg 

 and Leathern (1958) and traced to an im- 

 balance induced at the hypophyseal level. 

 In mice injected with estradiol or testos- 

 terone at 5 days of age there was a prema- 

 ture opening of the vagina followed by 

 conspicuous irregularities in the cycles. Ab- 

 normalities of the latter type were much 

 less marked when treatment with the ster- 

 oids was delayed until the 20th day. 



Results different from those reported by 

 Wilson and Wilson (1943) were also ob- 

 tained when young male guinea pigs, cas- 

 trated the day of birth, were injected daily 

 with testosterone propionate for 120 days 

 (Riss, Valenstein, Sinks and Young, 1955; 

 Gerall, 1958). The animals appeared normal 

 and the development of behavior was not 

 different from that in intact controls. The 

 difference in this case may be attributable 

 to the greater maturity of the guinea pig at 

 birth. 



The suggestion from the work on sexually 

 immature animals that androgens and es- 

 trogens do not have an organizing action on 

 l)atterns of behavior is reinforced by the 

 demonstration that the develoj^ment of sen- 

 sitivity to gonadal hormones can occur 

 when the gonads are absent. Female guinea 

 pigs and rats spayed immediately after 

 birth and first injected with estrogen and 

 progesterone 10 months (rat) and 2 years 

 (guinea pig) later were as reactive as ani- 

 mals ovariectomized during adulthood 

 (Wilson and Young, 1941). A female rat in 

 which there was congenital absence of the 

 ovaries, tubes, and uterus displayed typical 

 feminine behavior following injections of 

 estrogen and progesterone (Beach, 1945b). 

 The male is not different, for the capacity 

 to respond to androgen develops in the ab- 

 sence of the testes (Beach and Holz, 1946; 

 Riss, Valenstein, Sinks and Young, 1955). 



The problem of the manner of hormone 

 action in adults was brought into sharp 

 focus by Ball (1937a), although Goodale 

 had noted as early as 1918 that the behavior 

 of the capon receiving an implanted ovary 



