MAMMALIAN OVARY 



479 



mann, 1937; and others). Modern 

 counterparts are the reports of the in- 

 crease during pregnancy in the concen- 

 tration of serum precipitable iodine 

 (Heinemann, Johnson and Man, 1948; 

 Dowling, Freinkel and Ingbar, 1956a; 

 Tanaka and Starr, 1959), in serum thy- 

 roxine (Danowski, Gow, Mateer, Everhart, 

 Johnson and Greenman, 1950), and in the 

 accumulation of radioiodine (Pochin, 1952). 

 Some conflicting reports should be noted. 

 There was said to be no consistent altera- 

 tion in the concentration of serum pre- 

 cipitable iodine in oophorectomized women 

 (Stoddard, Engstrom, Hovis, Servis and 

 Watts, 1957), and Pochin (1952) found no 

 detectable variation in P^^ uptake during 

 the menstrual cycle in 5 women he studied. 

 Comparable observations have been made 

 on laboratory mammals (Greer, 1952; Soli- 

 man and Reineke, 1954; Soliman and Bada- 

 wi, 1956; Feldman, 1956a) and the baboon, 

 Papio ursinus (Van Zyl, 1957), except that 

 Brown-Grant (1956) could not agree from 

 his findings in the rat and rabbit that the 

 level of gonadal function exerts any striking 

 influence on thyroid activity in the normal 

 experimental animal. 



In man (Engstrom, Markardt and Lieb- 

 man, 1952; Engstrom and Alarkardt, 1954; 

 Bowling, Freinkel and Ingbar, 1956b) and 

 in laboratory mammals (chiefly the rat) 

 (Money, Kraintz, Eager, Kirschner and 

 Rawson, 1951; Feldman, 1956a; Feldman 

 and Danowski, 1956) the enhancement of 

 thyroid activity is attributed to the level 

 of circulating estrogen, whether it be endog- 

 enous or exogenous in origin. On the other 

 hand, many who have worked with labo- 

 ratory mammals have not found evidence 

 of augmented thyroid activity, and not in- 

 freciuently decreases were reported (see 

 Paschkis, Cantarow and Peacock, 1948; 

 and the numerous articles cited by Farb- 

 man, 1944; and Feldman, 1956a). The con- 

 flicting results may perhaps be accounted 

 for by the circumstance that the response of 

 the thyroid seems to be related to the dura- 

 tion of the estrogen treatment and to the 

 estrogen that was used. Decreases in thy- 

 roid activity have been reported when the 

 estrogen treatment was prolonged (Feld- 

 man, 1956a), and Money and his associates 

 showed clearly that estrone and some other 



components increased the collection of P-^^ 

 by the thyroid of rats whereas estradiol, 

 estriol, and diethylstilbestrol decreased the 

 collection. ]\Iany attempts have been made 

 to ascertain the nature of the mechanism 

 whereby the effective estrogenic substances 

 exert their action on the thyroid (Noach, 

 1955a, b; Feldman, 1956b; Dowling, Frein- 

 kel and Ingbar, 1956a, b; Bogdanove and 

 Horn, 1958). but they are so varied and 

 speculative that they will not be reviewed 

 here. 



The second category of observations re- 

 lated to the thyroid and ovarian functioning 

 includes those in which there is evidence of 

 action of thyroid hormone on the ovary. 

 Reviews of this work are contained in the 

 articles by Peterson, Webster, Rayner and 

 Young (1952), Hoar, Goy and Young 

 (1957), and Parrott, Johnston and Durbin 

 (1960) and most of their citations of work 

 done on the relationship of the thyroid 

 to the ovary will not be repeated here. 

 As they point out, many investigators 

 have reported that thyroidectomy is fol- 

 lowed by ovarian degeneration, arrested 

 folliculogenesis, and failure of ovulation. 

 Irregularity of the reproductive cycles 

 was common and much of this in the 

 guinea pig could be attributed to retarded 

 and sporadic follicular development (Hoar, 

 Goy and Young, loc cit.) . The latter in- 

 vestigators gave especial attention to the 

 condition of the ovaries in their hypothyroid 

 guinea pigs. In 10 pairs from thyroidec- 

 tomized animals (oxygen consumption and 

 heart rate were depressed) follicular de- 

 velopment was good in the sense that the 

 follicles appeared healthy, but a generation 

 of corpora lutea was missing in four. This 

 absence of corpora lutea, which is not seen 

 in normal adult guinea pigs, was believed 

 to be a consequence of the involution of the 

 older generation during the longer than nor- 

 mal interval between ovulations. It is con- 

 sidered significant in terms of the functional 

 capacity of such ovaries, that although the 

 percentage of sterile matings was higher 

 than in the controls, that, in the course of 

 the two studies at Kansas, 29 of 38 matings 

 were fertile. This experience may perhaps 

 account for the many reports (cited in tlu 

 papers from the Kansas laboratory) that 

 thvroidectomv or treatment with antithv- 



