In the male the anterior segmental tubes undergo remarkable modifications. There appear to grow from the first three or four or more of them (though the point is still somewhat obscure) branches, which pass to the base of the testis and there unite into a longitudinal canal, form a network, and receive the secretion of the testicular ampullæ (woodcut 9, nt). These ducts, the vasa efferentia, carry the semen to the Wolffian body, but before opening into the tubuli of this they unite into the longitudinal canal of the Wolffian body (l.c), from which pass off ducts equal in number to the vasa efferentia, each of which normally ends in a Malpighian body. From the Malpighian body so connected start the convoluted tubuli of what may be called the generative segments of the Wolffian body along which the semen is conveyed to the Wolffian duct (v.d). The Wolffian duct itself becomes much contorted and acts as vas deferens.
Diagram of the arrangement of the Urinogenital Organs in an adult
Female Elasmobranch.
m.d. Müllerian duct; w.d. Wolffian duct; s.t. glandular tubuli; five of them are represented with openings into the body-cavity; d. duct of the posterior segmental tubes; ov. ovary.
In the woodcuts, figs. 8 and 9, are diagrammatically represented the chief constituents of the adult urinogenital organs in the two sexes. In the adult female, fig. 8, there are present the following parts:
(1) The oviduct or Müllerian duct (m.d) split off from the segmental duct of the kidneys. Each oviduct opens at its anterior extremity into the body-cavity, and behind the two oviducts have independent communications with the general cloaca.
(2) The Wolffian ducts (w.d), the other product of the segmental ducts of the kidneys. They end in front by becoming continuous with the tubulus of the anterior segment of the Wolffian body on each side, and unite behind to open by a common papilla into the cloaca. The Wolffian duct receives the secretion of the anterior part of the primitive kidney which forms the Wolffian body.
(3) The ureter (d) which carries off the secretion of the kidney proper. It is represented in my diagram in its most rare and differentiated condition as a single duct.
(4) The glandular tubuli (s.t), some of which retain their original openings into the body-cavity, and others are without them. They are divided into two groups, an anterior forming the Wolffian body, which pour their secretion into the Wolffian duct, and a posterior group forming the kidney proper, which are connected with the ureter.