COLD-BLOODED VERTEBRATES 



10t)< 



TABLE n .2— Continued 



Occur regularly. 



maturity were males. Intramuscular injec- 

 tions of testosterone propionate into preg- 

 nant females, immature fish, and adult 

 nonjiregnant females caused complete mas- 

 culinization of some but not all fish. Male 

 sex characters were conspicuously developed 

 in all cases (Regnier, 1938, 1939). Baldwin 

 and Goldin (1939), Querner (1956), and 

 Vallowe (1957) in carefully controlled ex- 

 periments carried out a somewhat similar 

 series of injections and obtained masculini- 

 zation, in some cases with spermatogenesis, 

 of about half the experimental fish. Treat- 

 ment of female Lebistes and Platypoecilus 

 with androgens had little or no effect on the 

 ovaries except to suppress ovogenesis but 

 did stimulate the growth of male accessory 

 sex structures such as the gonojiodium 

 (Eversole, 1939; Regnier, 1939, 1942; Tay- 

 lor, 1948; Querner, 1956). Mohsen (1958) 

 more recently, however, gave relatively low 

 doses (0.015 or 0.03 mg. thrice weekly) 

 of pregneninolone to Lebistes for 6 months 

 after hatching and observed not only the 

 development of gonopodia in all treated fish 

 but the transformation of ovaries to ovo- 

 testes. Testes of treated males were normal, 

 except that the higher dose stimulated sper- 

 matogenesis. Testosterone propionate, para- 

 doxically, elicited the appearance of ova at 

 the base of an otherwise normal testis in 

 adult male Oryzias (Egami, 1955c). 



Not only androgen but estradiol benzoate, 

 progesterone, and desoxycorticosterone ace- 

 tate, if injected into the embryonic yolk sac, 

 feminized the genital ridges of Scyliorhinus 

 (Chieffi, 1954). Immature trout were parti- 

 ally feminized by keeping them in water to 

 which estrogen had been added (Padoa, 

 1939a). Injection of estrin into the body 

 cavity of the minnow Phoxinus laevis 

 caused l)reakdown of tlie testes and assump- 



tion of female coloration (Bullough, 1940b). 

 Administration of female sex hormones to 

 Lebistes males transformed the testes to 

 ovotestes and feminized the secondary sex 

 characters of immature, but not of mature, 

 males. Estrogen had no effect in females 

 (Berkowitz, 1938, 1941; Querner, 1956). 

 Various estrogens when given to Oryzias 

 caused the appearance of testis-ova (Egami, 

 1955b, c; Okada, 1943). Similar treatment 

 api)arently had the same result in immature 

 but not in mature male Xiphophorus (Val- 

 lowe, 1957). In Hepatus (Sey'raynis) hepatus, 

 treatment with estrogen stimulated the 

 growth of the hermaphroditic gonad (Pa- 

 doa, 1939b). 



Thus, the accessory sex structures of fish 

 apparently may be influenced by adminis- 

 tration of heterosexual sex hormones, par- 

 ticularly androgens, at any time, and the 

 sex of gonads of embryonic, immature, and 

 sometimes mature fish may be partially or 

 completely reversed by the same agents. 

 Further experiments w^ith special attention 

 to the histologic details of each stage of 

 reversal would be valuable, as would the 

 measurement of endogenous sex hormone 

 levels in blood and gonads. 



Amphibians 



See chapter by Burns. 



Reptiles 



Risley (1940) injected 0.25 mg. testos- 

 terone propionate in oily solution into the 

 eggs of the turtle, Chrysemys marginata 

 belli. The embryos were in the gastrula 

 stage. The mortality rate was high, and 

 only one injected male embryo survived. Of 

 the five surviving injected female embryos, 

 two had gonads with slight and three with 

 more advanced modification toward testes 



