1190 



HORMONAL REGULATION 



Gustavson, 1930; Robson and Henderson, 

 1936; Robson, 1938; Leathern, 1938), fer- 

 rets (Marshall and Hammond, Jr., 1945), 

 goats (Phillips, Fraps and Frank, 1946) , and 

 monkeys (Ball, 1936; Hartman, 1938). This 

 could be taken to indicate that progesterone 

 is not involved in the induction of sexual re- 

 ceptivity in these species. 



Theoretically, there is no reason why es- 

 trogens alone should not be sufficient, but 

 for several of these species an important 

 point has yet to be checked. Until the char- 

 acter of the behavior induced by the estro- 

 gen has been shown to be identical or nearly 

 identical with that displayed before ovariec- 

 tomy, the possibility of action by a small 

 amount of progesterone should not be ex- 

 cluded. Of the investigators mentioned 

 above. Bard appears to be the only one who 

 compared the behavior following treatment 

 with that before ovariectomy. He states that 

 2000 Allen-Doisy R.U. of estradiol benzoate 

 were sufficient to throw many cats into full 

 heat and that the estrus induced in this way 

 was in every respect the same as that which 

 occurs spontaneously. He never encountered 

 a cat in which full estrus could not be pro- 

 voked by giving estradiol benzoate or some 

 other form of estrin. 



When the hormonal induction of mating 

 behavior in the male was being described, it 

 was pointed out that individuals which were 

 characteristically high, medium, or low score 

 before castration returned to the correspond- 

 ing level during the period of replacement 

 therapy, whether the amount of injected tes- 

 tosterone propionate was 25 or 500 yug. per 

 100 gm. body weight per day. During studies 

 in which the hormonal induction of estrous 

 behavior in ovariectomized females was be- 

 ing investigated, some attention was given 

 to the character of the behavior following 

 repeated injections, although the experi- 

 ments were not as systematic as those on 

 the male. Nevertheless, the tendency for a 

 particular type of response to recur was re- 

 vealed when the length of estrus and the 

 character of the lordosis were being re- 

 corded (Boling, Young and Dempsey, 1938; 

 Goy and Young, 1957b) , when mounting be- 

 havior was being studied (Young and Rund- 

 lett, 1939), and during an investigation of 



the hormonal control of running activity 

 (Young and Fish, 1945). 



Despite an earlier report to the contrary 

 (Collins, Boling, Dempsey and Young,, 

 1938), and the fact that the length of heat 

 in the female guinea pig is not related to the 

 number of developing follicles (Young, My- 

 ers and Dempsey, 1933; Young, Dempsey, 

 Myers and Hagcjuist, 1938) , Goy and Young 

 (1957b) found that the length of heat in 

 sjiayed injected animals is related to the con- 

 ditioning quantity of estrogen. However, 

 this lengthening was made by the addition 

 of weak responses without any alteration in 

 the intensity curves; consecjuently, the in- 

 crease in the duration of estrus may not 

 represent a prolongation of the period of 

 receptivity to the male. Other data obtained 

 during the same experiment are consistent 

 with this suggestion. Tentatively, therefore, 

 the guinea pig seems to be a species in which 

 large quantities of male and female hor- 

 mones are not more stimulating to sexual 

 l)eiiavior than threshold amounts. 



The hormonal basis for male-like mount- 

 ing is in need of clarification. This behavior 

 coincides closely with estrus in many species 

 and is generally thought to be stimulated by 

 the ovarian hormones present at this time 

 (Hamilton, 1914, Carpenter, 1942b, for the 

 rhesus monkey; Corner, 1921, McKenzie, 

 1926, Altmann, 1941, for the pig; Williams, 

 1921, Hammond, 1927, for the cow; Long 

 and Evans, 1922, Hemmingsen, 1933, Beach, 

 1938, 1942f, Ball, 1940, for the rat; Ham- 

 mond, 1925, for the rabbit; Loeb, 1914, 

 Avery, 1925, Louttit, 1927; Young, Demp- 

 sey and Myers, 1935, for the guinea pig; 

 Yerkes, 1939, for the chimpanzee; Markley 

 and Bassett, 1942, for the marten; Pearson, 

 1944, for the shrew; Shadle, 1946, for the 

 porcupine; Beach, 1947, for the dog and cat. 

 It is exhibited by some apparently normal 

 chickens (Domm, 1947; Guhl, 1949) and 

 turkeys (Hale, 1955). 



Uncertainty with respect to the hormonal 

 basis of mounting behavior is introduced by 

 the fact that such behavior is seen under a 

 variety of conditions. In the guinea pig it is 

 easily induced by injections of estrogen and 

 progesterone (Young and Rundlett, 1939) 

 except in a strain in which it is not displayed 

 spontaneously (Goy and Young, 1957b). 



