684 



PHYSIOLOGY OF GONADS 



come smaller, ovulation fails, and large 

 vesicular follicles decrease in number with 

 an increase in atresia, but primary follicles 

 show a compensatory increase (Marrian 

 and Parkes, 1929; Mulinos and Pomerantz, 

 1940; Stephens and Allen, 1941; Guilbert, 

 1942; Bratton, 1957). The ovarian intersti- 

 tial cells mav be markedly altered or absent 

 (Huseby and Ball, 1945; Rinaldini, 1949) 

 and the ovary may exhibit excessive luteini- 

 zation (Arvy, Aschkenasy, Aschkenasy- 

 Lelu and Gabe, 1946) or regressing corpora 

 lutea (Rinaldini, 1949) . However, the ovar- 

 ian changes induced by inanition may be 

 reversed by refeeding, with a return to re- 

 productive capacity (Ball, Barnes and Vis- 

 scher, 1947; Schultze, 1955). The effect of 

 feed-level on the reproductive capacity of 

 the ewe has been reported (El-Skukh, Nulet, 

 Pope and Casida, 1955), but one must re- 

 alize that high planes of nutrition may ad- 

 versely influence fertility (Asdell, 1949). 

 Nevertheless, additional protein and cal- 

 cium added to an adequate diet extended 

 the reproductive life span (Sherman, Pear- 

 son, Bal, McCarthy and Lanford, 1956). 



2. Protein 



The availability of just protein has an 

 important influence on the female repro- 

 ductive system. In immature rats ovarian 

 maturation was prevented by feeding diets 

 containing per cent to 1.5 per cent protein 

 (Ryabinina, 1952) and low protein diets de- 

 creased the number of ova but without al- 

 tering their ribonucleic acid (RNA) or gly- 

 cogen content (Ishida, 1957). Refeeding 18 

 per cent protein for only 3 days was marked 

 by the appearance of vesicular follicles and 

 the release of estrogen in mice previously fed 

 a protein-free diet (Leathem, 1958a). In 

 experiments involving the opposite extreme, 

 in which 90 per cent protein diets were used, 

 a retardation of ovarian growth, and a de- 

 lay in follicular maturation, in vaginal 

 opening, and in the initiation of estrous 

 cycles were noted (Aschkenasy-Lelu and 

 Tuchmann-Duplessis, 1947; Tuchniann- 

 Duplcssis and Aschkenasy-Lelu, 1948). 



Adult female rats fed a protein-free diet 

 for 30 days exhibited ovaries weighing 22 

 mg. compared with ovaries weighing 56 mg. 

 from i)air-fed controls fed 18 per cent casein. 

 Ovarian glycogen, ascorbic acid, and cho- 



lesterol were all influenced by protein 

 deprivation and anestrum accompanied 

 the ovarian changes. Furthermore, uterine 

 weight and gl3^cogen decreased in rats fed 

 protein-free diets (Leathem, 1959b). 



In adult rats the feeding of 3.5 per cent 

 to 5 per cent levels of protein (GuillDert and 

 Gross, 1932) was followed by irregularity 

 of the cycles or by their cessation. The 

 cycles became normal when 20 to 30 per cent 

 protein was fed (Aschkenasy-Lelu and 

 Aschkenasy, 1947). However, abnormally 

 high levels of casein (90 per cent) in- 

 duced prolonged periods of constant estrus 

 (Tuchmann-Duplessis and Aschkenasy- 

 Lelu, 1947). Nevertheless, not all species 

 responded to protein depletion in the same 

 manner. For example, the rabbit exhibited 

 estrus and ovulation despite a 25 per cent 

 body weight loss imposed by to 2 per cent 

 protein diets (Friedman and Friedman, 

 1940). 



Despite a normal level of protein in the 

 diet, inadequate calories will interfere with 

 reproductive function and induce ovarian 

 atrophy (Escudero, Herraiz and Mussmano, 

 1948; Rivero-Fontan, Paschkis, West and 

 Cantarow, 1952). Furthermore, the effects 

 of 15 per cent and 56 per cent protein levels 

 on estrous cycles could not be distinguished 

 when calories were reduced 50 per cent (Lee, 

 King and Visscher, 1952). Returning mice 

 to full feeding after months of caloric de- 

 ficiency resulted in a sharp increase in re- 

 productive performance well above that ex- 

 pected for the age of the animal (Visscher, 

 King and Lee, 1952). This type of rebound 

 phenomenon has not been explained. 



Reproductive failure assigned to dietary 

 protein may be a reflection of protein 

 quality as well as level. Specific amino acid 

 deficiencies lead to cessation of estrus 

 (White and AVhite, 1942; Berg and Rohse, 

 1947) and thus feeding gelatin or wheat 

 as the protein source and at an 18 per cent 

 level was quickly followed by an anestrum 

 (Leathem, 1959b). Supplementation of the 

 wheat diet with lysine corrected the re- 

 productive abnormalities (Courrier and 

 Raynaud, 1932), but neither lysine (Pear- 

 son, Hart and Bohstedt, 1937) nor cystine 

 (Pearson, 1936) added to a low casein diet 

 was beneficial. Control of food intake must 

 be considered in studies involving amino 



