United States or Panama ? Vote for the TOP Country of the Week !
But in the Marsupials a communication is opened between the two Mullerian ducts, and in the Placentals they combine below with the rudimentary Wolffian ducts to form a single "genital cord." The original independence of the two wombs and the vaginal canals formed from their lower ends are retained in many of the lower Placentals, but in the higher they gradually blend and form a single organ.
In the Nibelungenlied we have a case in point. What the exact mythological elements contained in it represent it would indeed be difficult to say. Students of the Müllerian school have seen in Siegfried a sun-god, who awakens Brunhild, a nature goddess.
In the strings the young ova are distinguished by their considerable size from the surrounding follicle-cells. Two young Graafian follicles, isolated. In the male mammals there is the same fusion of the Mullerian and Wolffian ducts at their lower ends.
The two uteruses had a common cervix; the anterior of the two organs had no adnexa, though there were lateral peritoneal ligaments; it had become pregnant." Hollander explains the anomaly by stating that probably the Mullerian ducts or one of them had grown excessively, leading to a folding off of a portion which developed into the anterior uterus.
Ord describes a man in whom one of the Mullerian ducts was persistent. Anomalies of the Bladder. Blanchard, Blasius, Haller, Nebel, and Rhodius mention cases in which the bladder has been found absent and we have already mentioned some cases, but the instances in which the bladder has been duplex are much more frequent.
In all the Gnathostomes or all the Vertebrates from the fishes up to man a second similar canal develops beside the nephroduct at an early stage of embryonic evolution. The latter is usually called the Mullerian duct, after its discoverer, Johannes Muller, while the former is called the Wolffian duct.
The Mullerian ducts undergo very important changes in the female mammal. The oviducts proper are developed only from their upper part; the lower part dilates into a spindle-shaped tube with thick muscular wall, in which the impregnated ovum develops into the embryo.
In all the Gnathostomes the Wolffian duct is converted into the spermaduct, and the Mullerian duct into the oviduct. Only one of them is retained in each sex; the other either disappears altogether, or only leaves relics in the shape of rudimentary organs.
The origin of the Mullerian duct is still obscure; comparative anatomy and ontogeny seem to indicate that it originates by differentiation from the Wolffian duct. Both open behind into the cloaca. However uncertain the origin of the nephroduct and its two products, the Mullerian and the Wolffian ducts, may be, its later development is clear enough.
But while in the male mammal the Wolffian ducts develop into the permanent spermaducts, there are only rudimentary relics left of the Mullerian ducts. The internal sexual organs of the mammals undergo very distinctive changes of position. In woman the ovaries travel more or less towards the small pelvis, or enter into it altogether.
Word Of The Day