668 



PHYSIOLOGY OF GONADS 



many other findings prompt a survey of the 

 relationships of vitamins to reproduction. 



It is the intention of the author to review 

 enough of the evidence which interrelates 

 nutrition and reproduction to create an 

 awareness of the problems in the area. 

 Reviews dealing with the general subject 

 of hormonal-nutritional interrelationships 

 have been presented (Hertz, 1948; Samuels, 

 1948; Ershoff, 1952; Zubiran and Gomez- 

 Mont, 1953; Meites, Feng and Wilwerth, 

 1957; Leathem, 1958a,). Other reviews have 

 related reproduction to nutrition with em- 

 phasis on laboratory (Mason, 1939; Guil- 

 bert, 1942; Lutwak-Mann, 1958) and farm 

 animals (Reid, 1949; Asdell, 1949), and on 

 protein nutrition (Leathem, 1959b, c). An 

 encyclopedic survey of the biology of hu- 

 man nutrition has been made by Keys, 

 Brozec, Hernschel, Michelsen and Taylor 

 (1950). 



II. Nature of Problems in Nutritional 

 Studies 



A. THYEOID GLAND, NUTRITION, AND 

 REPRODUCTION 



Normal development of the reproductive 

 organs and their proper functioning in 



TABLE 12.1 

 Ovarian response to chorionic gonadrotrophin, 



as modified by thiouracil and diet 



(From J. H. Leathem, in Recent Progress in 



the Endocrinology of Reproduction, Academic 



Press, Inc., New York, 1959.) 



Chorionic gonadotrophin = 10 I. U. X 20 days. 



adults are dependent not only on the en- 

 docrine glands composing the hypophyseal- 

 gonadal axis, but on others as well. The 

 importance of the thyroid, although not 

 the same for all species, is readily apparent 

 from the effects of prolonged hypo- and 

 hyperthyroid states on reproduction. Many 

 of these effects have been enumerated else- 

 where (chapters by Albert, by Young on the 

 ovary, and by Zarrow) , but others also are 

 important. Thus steroid production may be 

 altered in hypothyroid animals; certainly 

 its metabolism is influenced. Myxedema is 

 associated with a profound change in andro- 

 gen metabolism. Endogenous production of 

 androsterone is very low and subnormal 

 amounts of administered testosterone are 

 converted to androsterone. Triiodothyronine 

 corrects this defect (Hellman, Bradlow, 

 Zumoff, Fukushima and Gallagher, 1959). 

 The gonads of male and female offspring of 

 cretin rats are subnormal. The testes may 

 contain a few spermatocytes but no sper- 

 matozoa, and Leydig cells seem to secrete 

 little or no androgen. The ovaries may con- 

 tain a few small follicles with antra, but 

 corpora lutea are absent and ovarian lipid 

 and cholesterol concentrations are very 

 low. Nevertheless, the gonads are com- 

 petent to respond to administered gonado- 

 trophin with a marked increase in weight. 

 However, administration of chorionic gon- 

 adotrophin to the hypothyroid rat stimu- 

 lated follicular cyst formation rather than 

 folliculogenesis and corpora lutea formation 

 (Leathem, 1958b), but, for even this aber- 

 rant development, dietary protein was re- 

 quired (Leathem, 1959b) (Table 12.1). The 

 relationship between hypothyroidism and 

 ovarian function may provide a clue to a 

 possible origin of ovarian cysts, long known 

 to be a common cause of infertility and as- 

 sociated reproductive disorders. Clinical 

 cases of untreated myxedema exhibit ovar- 

 ian cysts, and rats made hypothyroid for 

 eight months, had a higher percentage of 

 cystic ovaries than did euthyroid rats 

 (Janes, 1944). 



The reproductive system of the adult 

 male is less affected than that of the im- 

 mature male by a decrease in thyroid func- 

 tion, just as the testis of the adult is less 

 likely to reflect a change in protein nutrition 

 which is sufficient to alter the immature rat 



