664 



REPRODUCTION. 



FIG. 214. 



relaxed, the hemorrhage necessarily continues; but it is at once arrested 

 by contraction of the uterine walls. 



Regeneration of the Uterus after Delivery. Both the mucous mem- 

 brane and the muscular fibres of the uterus are replaced after delivery 

 by tissues of new formation. The decidua is discharged at parturition ; 

 and the hypertrophied muscular tissue, after serving for the expulsion 

 of the foetus, undergoes a process of retrogression and atrophy. 



A remarkable phenomenon connected with the renovation of the 

 uterine tissues, is the appearance in the uterus, during pregnancy, of a 

 new mucous membrane, underneath the old, and destined to take the 

 place of the latter after its discharge. 



If the uterus be examined immediately after parturition, it will be 

 seen that at the spot where the placenta was attached, every trace of 

 mucous membrane has disappeared. The muscular fibres in this situ- 

 ation are exposed ; and the mouths of the ruptured uterine sinuses are 

 also visible, their thin edges hanging into the cavity of the uterus, and ' 

 their orifices plugged with bloody coagula. 



Over the rest of the uterine surface the decidua vera has also disap- 

 peared. Here, however, notwithstanding the loss of the original mucous 

 membrane, the muscular fibres are covered with a semi-transparent film, 

 of whitish color and soft consistency. This film is an imperfect mucous 



membrane of new formation, 

 which begins to be produced, 

 underneath the decidua vera, as 

 early as the beginning of the 

 eighth month. The old mucous 

 membrane, or decidua vera, is 

 at this time somewhat opaque, 

 and of a slightly yellowish color, 

 from partial fatty degeneration. 

 It is easily separable from the 

 subjacent parts, owing to the 

 atrophy of its vascular connec- 

 tions ; and the new mucous mem- 

 brane beneath it is distinguish- 

 able by its fresh color and semi- 

 transparent aspect. 



The mucous membrane of the 

 cervix uteri, which takes no part 

 in the formation of the decidua, 



is not thrown off in parturition. After delivery it may be seen to ter- 

 minate at the os internum by a lacerated edge, where it was formerly 

 continuous with the decidua vera. 



Subsequently, a regeneration of the mucous membrane takes place 

 over the whole extent of the body of the uterus. The membrane of 

 new formation, already in existence at the time of delivery, becomes 

 thicker and more vascular ; and glandular tubules are gradually devel- 



MUSCULAR FIBRES OF THE UNIMPREGNATED HU- 

 MAN UTERUS ; from a woman aged 40, dead of 

 phthisis. 



