686 



PHYSIOLOGY OF GONADS 



a characteristic keratinizing metaplasia of 

 the uterus and vagina, but estrous cycles 

 continue despite the vaginal mucosal 

 changes. Furthermore, ovulation occurs 

 regularly until advanced stages of de- 

 ficiency appear. The estrous cycle becomes 

 irregular in cattle fed for a long period 

 of time on fodder deficient in carotene. The 

 corpora lutea fail to regress at the normal 

 rate and ovarian follicles become atretic and 

 cystic ( Jaskowski, Watkowski, Dobrowol- 

 ska and Domanski, cited by Lutwak-Mann, 

 1958). The alterations in reproductive or- 

 gans associated with a lack of vitamin A 

 may be due in part to a vitamin E deficiency 

 since the latter enhances the rate at which 

 liver stores of vitamin A are depleted. 



Definite effects of hypervitaminosis A 

 have been observed on reproduction. Masin 

 (1950) noted that estrus in female rats 

 could be prolonged by administration of 

 37,000 I.U. of vitamin A daily. The im- 

 plications, however, have not been studied. 

 The effect of hypervitaminosis A may actu- 

 ally induce secondary hypovitaminoses. 

 The displacement of vitamin K by excess 

 A is almost certain and similar relationships 

 appear to exist with vitamin D (Nieman 

 and Klein Obbink, 1954). 



The failure of vitamin E-deficient fe- 

 male rats to become pregnant is apparently 

 due to disturbances of the implantation 

 process rather than to the failure of ovu- 

 lation. There is no direct proof of ovarian 

 dysfunction (Blandau, Kaunitz and Slanetz, 

 1949). However, the ovary of the rat de- 

 ficient in vitamin E may have more con- 

 nective tissue and pigment, and Kaunitz 

 (1955) showed by ovarian transplantation 

 that some nonspecific ovarian dysfunction 

 appears to exist (cited by Cheng, 1959 (. 

 Vitamin E is essential for birds, but there 

 is little evidence for a dependency in most 

 mammals; sheep, cows, goats, and pigs have 

 been studied. Treatment of low-fertility 

 farm animals with tocopherol has not pro- 

 vided conclusive data favoring its use (Lut- 

 wak-Mann, 1958), nor has the treatment 

 of human females been rewarded with any 

 indication that vitamin E might be helpful 

 in cases of abnormal cycles and habitual 

 abortion (Beckmann, 1955). 



No specific reproductive disturbances in 

 man, the rhesus monkey, or the guinea pig 



have been associated with vitamin C de- 

 ficiency (Mason, 1939). Nevertheless, the 

 high ascorbic acid content of ovarian and 

 luteal tissue and of the adrenal cortex sug- 

 gests a physiologic role in association with 

 steroid synthesis. (3varian ascorbic acid 

 varies with the estrous cycle, dropping 

 sharply in the proestrum (Coste, Delbarre 

 and Lacronique, 1953), and decreasing in 

 resjionse to gonadotrophin (Hokfelt, 1950; 

 Parlow, 1958). Virtually no ascorbic acid is 

 present in bovine follicular fluid (Lutwak- 

 Mann, 1954) or in rat ovarian cyst fluid 

 (Blye and Leathem, 1959). Uterine ascorbic 

 acid decreased in immature mice treated 

 with estrogen, but remained unchanged 

 in rats following thiouracil administration 

 (Leathem, 1959a). Its role in the uterus 

 awaits elucidation. 



Delayed sexual maturation and ovarian 

 atrophy have been described when there 

 are deficiencies of thiamine, riboflavin, pyri- 

 doxine, pantothenic acid, biotin, and B12 

 (Ershoff, 1952; Ullrey, Becker, Terrill and 

 Notzold, 1955). However, as we noted when 

 deficiencies of the vitamins were being con- 

 sidered, much of the impairment of repro- 

 ductive function can be related to inanition 

 rather than to a vitamin deficiency (Drill 

 and Burrill, 1944). Pyridoxine deficiency, 

 although not affecting structure (Morris, 

 Dunn and Wagner, 1953) , markedly reduces 

 the sensitivity of the ovary to administered 

 gonadotrophin (Wooten, Nelson, Simpson 

 and Evans, 1958) . 



Bird, frog, and fish eggs contain consider- 

 able quantities of vitamins. In fact, the 

 daily human requirements for vitamins may 

 be contained in a hen's egg and thus it is 

 not surprising that hatchability is decreased 

 l)y virtually any vitamin deficiency. Lut- 

 wak-Mann (1958) has provided an excellent 

 survey of these data with numerous refer- 

 ences to studies of frogs and fishes. Nearly 

 all the B vitamins are present in fish roe 

 and the pantothenic acid concentration in 

 cod ovaries {Gadus morrhua) exceeds most 

 otlicr natural sources. The amount of the 

 latter varies with the reproductive cycle, 

 d(>creasing to its lowest level before spawn- 

 ing. Riboflavin and vitamin B12 , on the 

 other h;ui(l, do not change (Braekkan, 

 1955). 



