Search results
Results from the WOW.Com Content Network
Figure 1: Schematic diagrams of the epididymis of a reptile (A), monotreme mammal (B) and scrotal mammal (C) showing the anatomical caput, corpus and cauda, and the histologic initial segment, middle segment and terminal segment. The reptilian testis and epididymis typically undergo seasonal recrudescence coupled to the breeding season.
The epididymis is present in male reptiles, birds, mammals, and cartilaginous fish. [1] The caput epididymidis is fused to the testis in eutherian mammals, but not in marsupials. [13] In reptiles, there is an additional canal between the testis and the head of the epididymis and which receives the various efferent ducts.
Epididymis evolution from reptiles to mammals; Metadata. This file contains additional information, probably added from the digital camera or scanner used to create ...
Male monotremes are testicond (have intraabdominal testes) with the testes undergoing seasonal emergence during winter. The fully developed seminiferous tubules exhibit distinctly small stages of spermatogenesis in that more than one stage is often observed in a cross section of the tubule, [3] a characteristic of spermatogenesis that has also been observed in a reptile, [4] common in birds [5 ...
[9] [10] [11] Moreover, this increase in scrotal storage of sperm corresponds with epididymis evolution from reptiles to mammals. The mechanism by which sperm storage in the epididymis is enhanced at lower extra-abdominal temperatures has been shown to be a consequence of the biophysics of oxygen availability and sperm oxidative respiration. [12]
In amniotes (mammals, birds, and reptiles), the archinephric duct has become a true vas deferens, and is used only for conducting sperm, never urine. As in cartilaginous fish, the upper part of the duct forms the epididymis. In many species, the vas deferens ends in a small sac for storing sperm. [21]
At University of Newcastle (1978–1983), he conducted research on the evolution of the male reproductive tract as revealed by monotreme mammals.These studies showed that periurethral glands in the male monotreme represent a rudimentary disseminate prostate (prostate evolution in monotreme mammals), [1] and that the monotreme epididymis has many similarities to that of reptiles compared with ...
The hemipenis is the intromittent organ of Squamata, [4] which is the second largest order of vertebrates with over 9,000 species distributed around the world. They differ from the intromittent organs of most other amniotes such as mammals, archosaurs and turtles that have a single genital tubercle, as squamates have the paired genitalia remaining separate. [5]