In the course of further development, the mesonephric tubules increase in size, so that there ceases to be an interval between them, the mesonephros thus becoming a continuous gland.
The anterior mesonephric tubes are, moreover, formed earlier than the posterior.
In the case of Amia they open into the tubules or even directly into the mesonephric duct.
The mesonephric duct is now connected only with the anterior part of the kidney, and serves merely as a vas deferens or sperm duct.
The mesonephric ducts undergo fusion posteriorly in many cases to form a median urinary or urinogenital sinus.
The number of vasa efferentia varies and in the rays (Raia, Torpedo) may be reduced to a single one opening directly into the front end of the mesonephric duct.
Weldon showed that the cortical part of the suprarenals in the lizard was derived from the wall of the glomerulus of a number of mesonephric tubules.
The mesonephric tubules, called also the Wolffian body, open into this duct.
The recent observations of Brauer on the excretory organs of the Gymnophiona throw great doubt on the existence of mesonephricand pronephric tubules in the same segment.
The mesonephric tubules belong to segments posterior to those of the pronephros, are strictly segmental with the myotomes, and open into the pronephric duct.
A third series continuous with the mesonephric is situated in segments still more posterior, supplants the mesonephros and forms the kidneys of all the higher vertebrates.
He therefore argues that the pronephric duct indicates a series of pronephric tubules, which originally extended {403}along the whole length of the body, and were supplanted by the mesonephric tubules, which also belonged to the same segments.
In the majority of the lower Vertebrata the mesonephric tubes have at first a segmental arrangement, and this is no doubt the primitive condition.
The duct which receives the secretion of the anterior mesonephric tubules is the true mesonephricor Wolffian duct.
On the formation of the Muellerian duct, the duct of the mesonephros becomes the true mesonephricor Wolffian duct.
In most Teleostei the pronephros and mesonephros coexist through life, and their products are carried off by a duct, the nature of which is somewhat doubtful, but which is probably homologous with the mesonephric duct of other types.
The mesonephricduct receives the secretion of the anterior tubuli of the primitive mesonephros.
It receives the secretion of a certain number of the posterior mesonephric tubules, and usually unites with its fellow to form a kind of bladder, opening by a single pore into the cloaca, behind the anus.
This duct becomes in many forms divided longitudinally into two parts, one of which then remains attached to the segmental tubes and forms the Wolffian or mesonephric duct, while the other is known as the Muellerian duct.
The figure shews how the segmental duct becomes split into the Wolffian or mesonephric duct above, and Muellerian duct or oviduct below.
The above list will hopefully give you a few useful examples demonstrating the appropriate usage of "mesonephric" in a variety of sentences. We hope that you will now be able to make sentences using this word.
