1050 



SUBMAMMALIAN VERTEBRATES 



parently reach their maximal size and are 

 ovulated in June (Combescot, 1954b). 



Waldeyer (1870) mentions an investing 

 layer of germinal epithelium on the ovary 

 of Lacerta and the numerous layers of epi- 

 thelium in the mature follicle. Regamey 

 (1935) adds details. The ovary is supported 

 by a mesovarium developed from the dorsal 

 abdominal wall. Young ovocytes lie close to 

 the hilus. The ovary is invested with cuboi- 

 dal epithelium, but only the epithelium close 

 to the hilus is considered to be germinative. 

 Ovogenesis continues throughout the year. 

 Ripe follicles are seen in April and May, and 

 ovulation occurs at this time. Uromastix fol- 

 lows the same schedule (Kehl, 1935), as do 

 Eumeces (Breckenridge, 1943), Hemidacty- 

 lus (Dutta, 1944), and Sceloporus (Wood- 

 bury and Woodbury, 1945). It is believed 

 that Anolis ovulates alternately from the 

 right and left ovaries (Noble and Green- 

 berg, 1941) ; the ovaries are largest between 

 March and September (Dessauer, 1955). 

 This lizard produces single eggs at intervals 

 of about two weeks during a breeding season 

 lasting from midspring until the end of sum- 

 mer (Hamlett, 1952) . Usually only one ovum 

 matures at a time in Xantusia vigilis (Mil- 

 ler, 1948) . 



It seems that the snake Tropidonotus 

 viperinus mates in October or November and 

 ovulates in the following June or July, 

 whereas Coronella laevis mates in August 

 and September and ovulates in May and 

 June (Rollinat, 1898). The viviparous prai- 

 rie rattler, Crotalus v. viridis, ovulates late 

 in the spring or early in the summer. The 

 young are born in August or September. The 

 evidence is strong that the snake does not 

 ovulate the next year, but only in the spring 

 two years after the previous ovulatio;< 

 (Rahn, 1942). 



Alligators lay their numerous ( 100 to 200) 

 eggs in April or May after maturing to a 

 length of at least six feet (Cope, 1900; McU- 

 henny, 1935 ) . The immature alligator ovary 

 is lobulated (Reese, 1915). It consists of a 

 well defined cortex and a medulla (Forbes, 

 1937, 1940a). The cortex is invested with 

 germinal epithelium and contains numerous 

 immature follicles with eggs of various sizes. 

 The underlying medulla consists chiefly of 

 connective tissue strands (the remains of the 



medullary cords), between which are large 

 lacunae. The posterior third of the ovary is 

 composed of solid medullary tissue. This is 

 a "medullary rest"; it persists with little 

 change from the embryonic period, lacks 

 germinal epithelium, and resembles primi- 

 tive testicular tissue. 



XII. Sources of Estrogens 



Fish 



A few investigators have searched for es- 

 trogens in fish gonads. Assay of an extract 

 of 10 pounds of swordfish, Xiphias gladius, 

 ovaries showed less than 6 rabbit units of 

 estrogen (W^eisman, Mishkind, Kleiner and 

 Coates, 1937) . Ovaries of the flounder, Pseu- 

 dopleuronectes americanus, contain small 

 amounts of estrogen, as indicated by assay 

 of extracts in rats (Donahue, 1941). Chemi- 

 cal assay of 420 cc. pooled urine from 25 

 male and female Lophius piscatorius, the 

 angler fish, revealed 0.7 mg. folliculin, 1.5 

 mg. total phenolic steroids, 0.055 mg. 11- 

 oxy steroids, and 0.35 mg. 17-ketosteroids 

 (Brull and Cuypers, 1954). The mature ova 

 of the dogfish, Mustelus canis, contain a 

 large amount of estrogen (Hisaw and 

 Abramowitz, cited bv Pickford and Atz, 

 1957). 



The production of estrogens by fish ova- 

 ries deserves vigorous study. The results 

 might well shed light not only on morpho- 

 logic changes but on reproductive behavior. 

 Perhaps migration itself is stimulated in part 

 by sex hormones. 



Amphibians 



The writer has found only one pertinent 

 report (Grant, 1937), and that without de- 

 tails: an "estrogenic substance can be ex- 

 tracted from amphibian ovaries." Further 

 research is desirable, but no doubt has been 

 impeded by the problem of obtaining enough 

 ovarian tissue to yield detectable amounts 

 of sex hormone. 



Reptiles 



Injection daily for four days of 0.1 cc. 

 follicular fluid from the ovaries of Crotalus 

 terrificus provoked vaginal estrus in castrate 

 mice (Fraenkel and Martins, 1938). Alco- 

 holic extracts of the ovaries of crotalid 



