Brauer's evidence seems to me to signify that the pronephros, mesonephros, and metanephros are all serially homologous, and that the pronephros bears much the same relation to the mesonephros that the mesonephros does to the metanephros.
So, also, Price, from his investigations of the excretory organs of Bdellostoma, considers that in this animal both pronephros and mesonephros are derived from a common embryonic kidney, to which he gives the name holonephros.
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.
For this reason Semon can speak of the mesonephros as a dorsal derivative of the pronephros, just as Sedgwick says that the external or somatic vesicle of Peripatus is a derivative of the appendicular nephric organ.
Such a derivation appears to me to afford an explanation of the difficulties connected with the origin of the pronephros and mesonephros respectively, which is more satisfactory than that given by the direct derivation from the annelid.
According to the much more probable and reasonable view, the pronephros represents the oldest and original excretory organs, while the mesonephros is a later formation.
In the mesonephros they remain separate and in this case the portion of coelom surrounding the glomerulus tends to be nipped off from the general coelom--to form a Malpighian body.
The anterior portion of the mesonephros is much reduced in size in correlation with the fact that it has lost its renal function.
Anterior (genital) portion of mesonephros with its coiled duct.
In the region between the pronephros and the front end of the fully developed part of the mesonephros very rudimentary tubules had become established.
On the accomplishment of these changes, the pronephros is essentially provided with all the parts typically present in a segment of the mesonephros (woodcut, fig.
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 next part of the system to appear is the mesonephros or Wolffian body.
The mesonephros of the Ammocoete undergoes at the metamorphosis complete atrophy, and is physiologically replaced by a posterior series of segmental tubes, opening into the hindermost portion of the segmental duct (Schneider).
While the lumen is gradually being formed, the segmental tubes of the mesonephrosbecome established.
The mesonephros is formed some distance behind, and some time after the pronephros, both in Acipenser and Lepidosteus, so that in the larvae of both these genera the pronephros is for a considerable period the only excretory organ.
Posteriorly the Muellerian ducts and the ducts of the mesonephros remain united.
In connection with the segmental features of the mesonephros it is perhaps worth recalling the fact that in Elasmobranchii as well as other types there are traces of segmental tubes in some of the postanal segments.
The mesonephros (r), divided into an anterior sexual part connected with a rudimentary testicular network, and a posterior part.
Mesonephros and Metanephros, the kidney, and their unseparated ducts, the ureters.
The above list will hopefully give you a few useful examples demonstrating the appropriate usage of "mesonephros" in a variety of sentences. We hope that you will now be able to make sentences using this word.
