COLD-BLOODED VERTEBRATES 



1049 



oviduct and uterus. In the dogfish, Scylio- 

 rhinus canicula, abdominal cilia, present 

 only in the adult female, move the ova from 

 the ovary to the oviduct (Metten, 1939). 



The varieties of female reproductive tract 

 in the bony fish were long ago categorized 

 by Brock (1878) on the basis of his study 

 of 57 species in almost as many genera. In 

 one class the solid ovary has no excurrent 

 duct, eggs being discharged into the coelomic 

 space and escaping by way of the abdominal 

 pore. The ovary may consist of a single layer, 

 as in the eel Anguilla, or of several layers, as 

 in the Salmonidae. In a second category of 

 fish the ovary is a sac, closed anteriorly and 

 ending posteriorly in an oviduct. Only a lit- 

 tle of the ovarian wall may contain eggs, as 

 in Scorpaena, Lepadogaster, and Ophidmm, 

 or most of the wall may be filled with eggs 

 carried in masses which are knob-shaped in 

 cross section, as in Lophobranchis and Blen- 

 nius, or in lamellae. MacLeod (1881) also 

 recognized these two classes of ovary. He 

 pointed out that in the first, or solid, type 

 the medial surface {face vasculaire) is 

 smooth, invested with endothelium, and 

 lacks germinal epithelium. The lateral sur- 

 face, or face germinative, is covered with 

 egg-bearing folds and germinal epithelium. 

 The solid type of ovary is seen in salmonid 

 and murenid fish. In all other bony fish, the 

 paired ovaries are hollow ; their external sur- 

 face is vascular, whereas the interior is in- 

 vested with germinal epithelium. The ovar- 

 ian sac ends posteriorly in an oviduct. Right 

 and left oviducts join to form a common 

 canal which opens through the body wall 

 between anus and urinary orifice. Part or 

 all of the internal, or ovigerous, surface of 

 the ovary is folded in a variety of patterns. 



The ovary of Fundulus as described by 

 Matthews (1938) belongs in the second cat- 

 egory. This ovary is single but bilolx'd an- 

 teriorly. (Ovigerous lamellae project into its 

 central cavity. Follicles may begin to ma- 

 ture at any time of year. The ovary is small- 

 est in July, increases slowly in size until 

 April, then grows rapidly until o\'uhition in 

 June. The ovaries of Neotoca and Oryzias 

 also belong in this class (Mendoza, 1940; 

 Robinson and Rugh, 1943). 



Oviposition necessarily coincides with the 



shedding of sperm by the male in those fish 

 in which fertilization is external. 



A))ip}ubiatis 



Ovulation and fertilization occur during 

 the spring in most amphibians (Smith, 

 1955). In Rana pipiens the the cyst-like fol- 

 licle bulges as it matures (Rugh, 1935). 

 Eventually it ruptures at the stigma, not 

 abruptly but in less than a minute. The ovum 

 slowly emerges, being forced through an 

 aperture smaller than the egg itself. The fol- 

 licles of the frog's ovary can be rui^tured ar- 

 tificially by pressure or by the application 

 of a pepsin-hydrochloric acid mixture 

 (Rugh, 1935; Kraus, 1947). Smooth muscle 

 fibers are a normal component of the am- 

 phibian ovary. Kraus and others have noted 

 that the muscle fibers are larger in the ma- 

 ture than in the immature ovary. Tlie fibers 

 contract rhythmically, not only during ovu- 

 lation but at other times. Their role, if any, 

 is not clear. Rugh believes that normal fol- 

 licular rupture follows, and is due to local 

 changes induced earlier by pituitary hor- 

 mones. It is interesting that if ripe follicles 

 are excised they still may ovulate up to 12 

 hours later. Thus the final release of the 

 ovum would seem to be an autonomous proc- 

 ess. 



Reptiles 



Important early descriptions of the adult 

 reptilian ovary include those of von Leydig 

 (1853, 1872)"^ Waldeyer (1870), Braun 

 (1877), and Loyez (1905-1906). In turtles 

 and lizards the ovaries are round and plump ; 

 in snakes, elongated; in the immature alli- 

 gator, flat and ratlier long (Reese, 1915; van 

 den Broek, 1933; Forbes, 1937). 



The musk turtle, Sternotherus odoratus, 

 breeds in April and early May and ovulates 

 usually between May 15 and 20. The eggs 

 are carried in the oviducts for 20 to 35 days, 

 then laid (Risley, 1933a). The box turtle, 

 Terrapene Carolina, ovulates in .June and 

 July and lays its eggs soon afterward (Alt- 

 land, 1951). Munson (1904) says that the 

 ovaries of the tortoise, CleniDu/s niannorata, 

 fill most of the abdominal ca\ity when the 

 eggs have acquired all of their yolk. In an 

 Algerian tortoise, Emys leprosa, the eggs ap- 



