MAMMALIAN OVARY 



457 



theca externa in ovaries from the cow, pig, 

 rabbit, and guinea pig. The earlier con- 

 tradictory results he reviewed were at- 

 tributed to the nonspecificity of the older 

 staining methods. A possible clue to the 

 mechanism of ovulation wliich does not seem 

 to have been explored was given by the ob- 

 servations of Boling, Blandau, Soderwall 

 and Young ( 1941 ) when they were studying 

 follicular growth in the rat. Immediately 

 before ovulation, but at no other time, a 

 large pocket at the base of the cumulus, 

 and described as an invagination of the 

 granulosa, is a constant feature of follicu- 

 lar structure (Fig. 9 in their article). No 

 guess w^as made as to its significance. 



In all the spontaneously ovulating infra- 

 human mammals that have been studied, 

 except the dog (Evans and Cole, 1931 ) , 

 possibly other Canidae, and the mouse 

 (Snell, Fekete, Hummel and Law, 1940) 

 in which it takes place early in estrus, ovu- 

 lation occurs toward the end of heat (see 

 reviews in Young, 1941; Dukes, 1943; and 

 more recent articles on the chimpanzee, rhe- 

 sus monkey, baboon, cow, and mare by 

 Young and Ycrkes, 1943; van Wagenen, 

 1945, 1947; Gillman and Gilbert, 1946; 

 Cordiez, 1949; and Trum, 1950; respec- 

 tively ) . Only in the human female in which 

 cyclic waxing ^nd waning of sexual desire 

 is not easily detected does uncertainty exist. 



Since an early period, when emphasis was 

 given to the opinion that ovulation occurs 

 about midway in the intermenstrual inter- 

 val (Knaus, 1935; Hartman, 1936; Farris, 

 1948), much evidence has been produced 

 indicating that it may occur at other times 

 as well, even during menstruation (Teacher, 

 1935; Rubenstein, 1939; Sevitt, 1946; Berg- 

 man, 1949; Stieve, 1952; and many others). 

 If we may judge from what has been found 

 in the chimpanzee (Young and Yerkes, 

 1943), baboon (Gillman and Gilbert, 1946), 

 ihcsus monkey (Rossman and Bartclmez, 

 1946), and man (Bergman, 1949; Buxton, 

 1950), irregularities in the length of the 

 preovulatory and postovulatory phases of 

 the cycle complicate the problem and could 

 account for some of the confusion. In the 

 chimjianzee, baboon, and human female, in 

 which the irregularities can be located wdth 

 respect to the time of ovulation, age in- 

 fluences the length of both phases, and fol- 



lowing pregnancies there are similar ir- 

 regularities. In the baboon, environmental 

 stresses result in temporary or even pro- 

 longed inhibition of ovarian activity. There 

 is no reason for believing that the same fac- 

 tors have less effect on folliculogenesis in 

 the human female; irregularities in adoles- 

 cence (Engle and Shelesnyak, 1934) and fol- 

 lowing pregnancy (Sharman, 1950, 1951) 

 are common and there are many reports of 

 psychic effects (see reviews by Kelley, 1942; 

 Kelley, Daniels, Poe, Easser and Monroe, 

 1954; Kroger and Freed, 1950; Randall and 

 McElin, 1951; Bos and Cleghorn, 1958). 

 In all cases follicular growth is interrupted 

 and amenorrhea follows. But if the esti- 

 mates are correct that the average fertile 

 woman ovulates normally about 85 per cent 

 of the time (Farris, 1952), or that perfectly 

 healthy women may have 3 or 4 anovulatory 

 cycles a year (de Allende, 1956; also see 

 table in Bergman, 1949), there must also 

 be cases in which much of follicular growth 

 is normal, or at least adequate to stimulate 

 growth changes in the uterus, but ovulation 

 does not occur. As if the complications noted 

 above are not enough, the reviews of the 

 methods used in determining the time of 

 ovulation (D'Amour, 1934; Cohen and 

 Hankin, 1960) and the critical study of 

 Buxton and Engle (1950) in which an at- 

 tempt was made to correlate basal body 

 temperature, the condition of the endome- 

 trium, and the stage of folliculogenesis in 

 the ovary, suggest either that a really sensi- 

 tive indicator of the time of ovulation has 

 not been found, or if one exists, that it has 

 not been used in a study sufficiently sys- 

 tematic to reveal the true situation in the 

 human female. The problem is one of the 

 many that is with us very much as it was 

 20 years ago. 



E. FOLLICULOCJENESIS IN PREGNANCY 

 AND LACTATION 



Before leaving the subject of follicular 

 growth, its course in pregnancy and lacta- 

 tion should be reviewed. Information has 

 been obtained from many species, but in 

 most cases it is not complete and a con- 

 siderable amount of conjecture is necessary. 

 What is certain is that pregnancy affects 

 the process of folliculogensis in many ways ; 

 each must be the reflection of a different in- 



