. Outlines of zoology. Zoology. EXCRETORY AND REPRODUCTIVE SYSTEMS. 497 ap. The segmental duct of each side divides into Wolffian and Miillerian ducts. The Wolffian duct becomes in the male the vas deferens, in the female it is an unimportant Wolffian duct; the Miillerian duct becomes in the female the oviduct, in the male it is a mere rudiment. The muscles and other organs of Elasmobranchs retain considerable quantities of nitrogenous waste products. There can be no doubt that the body-cavity helps in excretion, and gets rid of waste through the two abdominal pores. In some Elasmobranchs thes
. Outlines of zoology. Zoology. EXCRETORY AND REPRODUCTIVE SYSTEMS. 497 ap. The segmental duct of each side divides into Wolffian and Miillerian ducts. The Wolffian duct becomes in the male the vas deferens, in the female it is an unimportant Wolffian duct; the Miillerian duct becomes in the female the oviduct, in the male it is a mere rudiment. The muscles and other organs of Elasmobranchs retain considerable quantities of nitrogenous waste products. There can be no doubt that the body-cavity helps in excretion, and gets rid of waste through the two abdominal pores. In some Elasmobranchs these are re- placed by openings (nephro- stomes) into the kidney. Occasionally there are both nephrostomes and abdo- minal pores. The male organs or testes lie on each side of the cardinal sinus, moored by a fold of peritoneum. Sperma- tozoa pass from the testis by vasa efferentia into a tube surrounded anteriorly by epididy- mis. The tube of the epididymis is continued into the vas deferens, which is dilated pos- teriorly into a seminal vesicle and an adjacent sperm-sac. Finally, the two vasa deferentia open into the urogenital sinus, whence the spermatozoa pass into the cloaca. Thence, in copulation, they pass into the complex " claspers " of the male, which are said to be inserted into the cloaca of the female. The female organs or ovaries lie on each side of the car- dinal sinus, moored by a fold of peritoneum. In young skates they are like the young testes, but in the adults they 32. Fig. 212.—Urogenital organs of female skate.—In part after Monro. a-p., Aperture of united oviducts; , Wolffian duct; ov., ovary ; , oviducal gland ; .£., egg in mermaid's purse; Bl., bladder at base of Wolffian ducts (arrow into cloaca); kidney; arrow from base of oviduct into Please note that these images are extracted from scanned page images that may have been digitally enhanced for readability - coloration and appearance of these illustrations may not p
Size: 1334px × 1874px
Photo credit: © The Book Worm / Alamy / Afripics
License: Licensed
Model Released: No
Keywords: ., bookauthorth, bookcentury1800, bookdecade1890, booksubjectzoology
