1058 



SUBM A M M ALIAN VERTEBR ATES 



lization is somehow accomplished without 

 an intromittent organ. In .V. vivipara as 

 many as one hundred larvae may develop in 

 the bicornuate uterus. The larvae have long, 

 vascular tails which possibly maintain con- 

 tact with the uterine wall to permit respira- 

 tory exchange (Noble, 1931). In N. occiden- 

 talis (Angel and Lamotte, 1944; Lamotte 

 and Tuchmann-Duplessis, 1948 1, each slim 

 oviduct is dilated posteriorly to form a uter- 

 ine horn. The two horns, which join caudally, 

 are muscular, well vascularized, and lined 

 with columnar epithelium. In pregnancy the 

 oviduct does not change, but the horn en- 

 larges as its one to ten embryos grow. There 

 is no placenta; the fluid in which the em- 

 bryos rest may supply nourishment and oxy- 

 gen. The young are retained until after 

 metamorphosis. When born, they may be 

 two-fifths the length of the mother. 



A", occidentalis has been found only at an 

 elevation of 1200 meters, in fields on top of 

 Mount Nimba in French Guinea. The gesta- 

 tion period is from September to June (La- 

 motte and Rey , 1954 ) . During the dry season 

 (December to February) no specimens were 

 found, and it is believed that the adults may 

 aestivate at this time. It may be that vivi- 

 parity represents an adjustment to an en- 

 vironment which not only lacks bodies of 

 water for incubation of eggs but which has 

 the added hazard of a dry season. This frog 

 is also typically viviparous in that only 10 

 to 30 ova are found in an animal and that the 

 eggs have almost no yolk (Lamotte, Rey 

 and Vilter, 1956) . 



Reptiles 



Many snakes and lizards are viviparous. 

 Several types of placentae occur, and pla- 

 cental exchange takes place. -'^ Fraser and 

 Renton (1940) call attention to the simi- 

 larity between the uterine epithelium under- 

 lying the allantoplacenta in the lizard Lygo- 

 soma ocellatum, as described by Weekes 

 (1930), and the expanded pericardium 

 through which respiratory and nutritional 

 exchange take place in the embryo of the 

 viviparous fish, Heterandria jonyiosa. 



'^Flvnn, 1923; Harrison and Weekes, 1925; 

 Weekes, 1927a, 1929, 1930, 1935; Rahn, 1939; Boyd, 

 1942; Dutta, 1946; Heimlirli and Heimlicli, 1950; 

 Kasturirangan, 1951; Bellaiis, Giiffit)is and Bel- 

 laiis. 1955; Clark, Florio. and Huiowitz, 1955. 



XX. Corpus Luteum 



Fish 



Structures resembling corpora lutea occur 

 in widely divergent types of fish — the myx- 

 inoids Bdellostoma and Myxine (Conel, 

 1917), the elasmobranchs Spinax (Wallace, 

 1903), Squalus (Hisaw and Albert, 1947), 

 Cetorhinus (Harrison Matthews, 1950), 

 Myliobatis (Giacomini, 1896a), and several 

 teleosts, including Lebistes (Stolk, 19511)), 

 Rhodeus ( Bretschneider and Duyvene de 

 Wit, 1947 ) , and Fundulus (Matthews, 1938 ) . 

 The corpora persist during pregnancy in vi- 

 viparous species. Mendoza (1943), however, 

 feels that the corpus luteum of Neotoca, be- 

 cause it lacks any indication of endocrine ac- 

 tivity, cannot be compared to the mamma- 

 lian corpus luteum. Physicochemical assay 

 of blood drawn from carp, Cyprimis carpio, 

 in October, after the spawning season, did 

 not reveal the presence of progesterone 

 (Bondy, Ui)ton and Pickford, 1957). Hisaw 

 and Abramowitz (cited by Pickford antl Atz, 

 1957) failed to find progesterone in the cor- 

 jiora lutea of the dogfish, Mustelus earns, 

 and removal of the corpora lutea during 

 pregnancy did not affect the embryos. It is 

 possible, as suggested by various authors, 

 that acciuisition of an endocrine function by 

 the corpus luteum was a somewhat belated 

 evolutionary development. This area de- 

 serves fui-tlicr investigations. 



Amphibians 



Corpora lutea have l)een reported in 

 Rana, Xectophrynoides, Bufo, Triton, Sala- 

 mandrina, and Salamandra (Giacomini, 

 18961); Hett, 1923; Lamotte and Rey, 1954), 

 although Duscliak (1924) denies that cor- 

 poi'a occur in Rana. 



Reptiles 



Altland (1951) has described the cori)us 

 luteum of the box turtle, Terrapene c. 

 Carolina, and Rahn (1938), that of the 

 snapping turtle. In general, the corpora re- 

 semble those of mammals. A curious fea- 

 ture of the reptilian corpus luteum is the 

 absence of blood vessels in the central epi- 

 thelial portion. The box turtle's corpora are 

 present in June, the month when the eggs 



