. Comparative anatomy of vertebrates. Anatomy, Comparative; Vertebrates -- Anatomy. 332 COMPARATIVE MORPHOLOGY OF VERTEBRATES. The testes, supported by mesorchia, lie at various levels-in the coelom. The relations of their ducts to the mesonephros are typical (p. 521). The vasa deferentia of the two side unite just before entrance into the cloaca to form a urogenital sinus, with which an oval sperm sac is connected on either side. In Chimcera the genital portion of the mesonephros (fig. 331) is widely separated from the functional por- tion, the two being connected by the Wolffian duct. In the
. Comparative anatomy of vertebrates. Anatomy, Comparative; Vertebrates -- Anatomy. 332 COMPARATIVE MORPHOLOGY OF VERTEBRATES. The testes, supported by mesorchia, lie at various levels-in the coelom. The relations of their ducts to the mesonephros are typical (p. 521). The vasa deferentia of the two side unite just before entrance into the cloaca to form a urogenital sinus, with which an oval sperm sac is connected on either side. In Chimcera the genital portion of the mesonephros (fig. 331) is widely separated from the functional por- tion, the two being connected by the Wolffian duct. In the male the Miillerian duct is rudimentary and frequently is with- out a lumen. GANOIDS.—Nothing is known of the development of the sexual organs of the ganoids, except as to the origin of the germ cells in two species. In most species the ovary is band-like and the oviducts open by broad funnels into the ccelom, but in Lepi- dostens the ovary is saccular, the eggs pass- ing into the central cavity, the duct being apparently a sterile, backward prolongation of the ovary. In the male the testes are frequently lobulated and a system of effer- ent ductules, connected by a longitudinal canal, pass from the testes into the meso- nephros (fig. 325) and thence separately or by a single tubule into the Wolffian duct. In the males of all but Lepidostcus there are short tubes with funnels, appar- ently the homologues of the oviducts of the females. TELEOSTS.—In some of the lower teleosts (salmonids, etc.) the elongate ovary is solid and the eggs pass from it into the ccelom and are carried thence to the exterior by short peritoneal funnels (fig. 332), or the tubes and funnels may be absent and the eggs then pass out by abdominal pores. is a closed sac (like that of Lepidosteus, fig. 326) continued behind by a slender oviduct. The ducts of the two sides may open separately, but usually their hinder ends are united and open by a single genital pore between the anus and the rectum In some
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Keywords: ., bookcentury1900, bookdecade1910, booksubjectanatomy, bookyear1912
