THE MULLERIAN DUCTS 



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animals, and certain malformations of the genital tract which occur in the human 

 subject, involving a greater or lesser degree of duplicity of the tract, are explained 

 by defective fusion of the ducts. Meanwhile the urogenital sinus shortens, the 

 vaginal bulbs elongate, and the Miillerian eminence is brought close to the surface. 

 It follows that when the opening out of the fused solid ends of the ducts takes 

 place the orifice is superficial, and the urogenital sinus is only represented by the 

 vestibule of the vagina. 



For a considerable period the vagina is solid. Opinions differ as to the origin of this 

 condition. According to one view (Nagel) it is primary, the vagina being formed from the 



FIG. 247. SECTION THROUGH A HUMAN EMBRYO OF 30 MM. ABOUT THE BEGINNING 

 OF THE THIRD MONTH. (T. H. Bryce.) 



Below the spinal cord is seen the body of a vertebra with the iiotochord, and on each side of the 

 cord the neural arch ; between them a pair of spinal ganglia. The large cartilages on each side are 

 the ilia. The peritoneal cavity is bridged over by the genital cord formed by the fusion of the Wolffian 

 mesenteries ; in the cord are seen the two Miillerian ducts about to fuse, and externally the Wolffian 

 ducts. Above the genital cord is the rectum ; in the wall of the pelvis, one on either side, the ureters ; 

 below the cord the bladder and allantoic arteries. On each side of this the peritoneal cavity is interrupted 

 by a fold, the plica gubernatrix extending from the Wolffian mesentery to the inguinal region, 

 liotice how at the inguinal attachment of these folds the muscular tissue of the abdominal wall extends 

 into the gubernaculum. 



elongated epithelial mass in which the Miillerian ducts end. According to Berry Hart and 

 F. Wood- Jones, who adopt a' very similar explanation, two separate epithelial cords are formed, 

 which fuse to give rise to the solid vagina. According to another view, the condition is 

 secondary, and is due to the temporary fusion of the epithelial walls. The cavity is produced 

 or restored by the shedding of the central cells after the fourth month. Opinions also 

 differ as to the origin of the hymen. According to the most generally accepted view, it 

 represents the remains of the margins of the opening of the thickened ends of^ the fused 

 ducts into the urogenital sinus. Berry Hart, and also recently Kempe, have, however, derived 

 it from the epithelium in which the genital ducts end. 



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