274 EMBRYOLOGY. 



roots " of which are firmly grown together with the 

 uterine mucosa by means of their tips, whereas the 

 free processes project into the cavernous blood-spaces 

 of the placenta uterina. 



(6) The placenta uterina, like the decidua vera, is composed of 

 a compact layer, which becomes detached at birth (pars 

 caduca), and a spongy layer, in which the separation 

 takes place, a part remaining behind on the musculature 

 (pars fixa). 



The compact layer (basal plate of WINKLEK) sends 

 partition-walls (septae placentae) between the chorionic 

 tufts, and thereby divides them into separate bundles, 

 the cotyledons. 



There are interpolated between the arteries and veins 

 which run in the basal plate and the septse enormously 

 enlarged vascular spaces, in which the villi appear to 

 hang free. 



The vascular spaces are probably extraordinarily 

 distended maternal capillaries, in which case one may 

 expect to find the chorionic villi invested by a very thin 

 layer of maternal tissue (endothelial membrane), as is 

 maintained by some investigators. 



7. At birth the deciduse or caducous membranes become detached 

 from the uterus along the spongy layer, and together with the foetal 

 envelopes and the placenta constitute the after-birth. 



8. In the. first weeks after birth a normal mucosa is developed 

 out of the remnants of the spongy layer left upon the musculature 

 and the remnants of the uterine glands, from the epithelium 

 of which the epithelium of the mucous membrane is probably 

 regenerated. 



LITERATURE. 



Ahlfeld, Friedr. Beschreibung eines sehr kleinen menschlichen Eies. 

 Archiv f. Gynakologie. Bd. XIII. 1878. 



Beigel, Herm., und Ludw. Loewe. Beschreibung eines menschlichen 

 Eichens aus der 2. bis 3. Woche der Schwangerschaft. Archiv f . Gynako- 

 logie. Bd. XIT. 1877. 



Beigel. Der dritt kleinste bisher bekannte menschliche Embryo. Archiv f. 

 Gynakologie. Bd. XIII. 1878. 



Braun, G. Ein Abortivei aus dem 3. Schwangerschaftsmonat. Centralblatt 

 f. Gynakologie. Jahrg. XIII. 1889. 



Breus, K. Ueber ein menschliches Ei aus der 2. Woche der Graviditat. 

 Wiener medicin. Wochenschrift 1877. 



