ATTACHMENT OF EGG TO UTERUS. 753 



If abortion occur at this time, the mucous membrane of the uterus, 

 that is, the decidua vera, is thrown off, and brings with it the egg and 

 the decidua reflexa. On examining the mass so discharged, the egg 

 will be found imbedded in the substance of the decidual membrane. 

 One side of the membrane, where it has been torn away from its attach- 

 ment to the uterus, is ragged ; the other side, corresponding to the cavity 

 of the uterus, is smooth or gently convoluted, and exhibits distinctly 

 the orifices of the uterine tubules; while the egg itself can only be 

 extracted by cutting through the decidual membrane, either from one 

 side or the other, and opening in this way the special cavity in which it 

 is inclosed. 



During the formation of the decidua reflexa, the entire egg, as well 

 as the body of the uterus which contains it, has considerably enlarged. 

 That portion of the uterine mucous membrane situated immediately 

 underneath the egg, and to which it first became attached, has also con- 

 tinued to increase in thickness and vascularity. The remainder of the 

 decidua vera, however, ceases to grow as before, and no longer keeps 

 pace with the increasing size of the egg and of the uterus. It is still 

 thick and vascular at the end of the third month ; but after that period 

 it becomes comparatively thinner and less glandular, while the activity 

 of growth is concentrated in the egg, and in that portion of the uterine 

 mucous membrane with which it is in immediate contact. 



Attachment of the Egg to the Uterus. While the above changes are 

 taking place in the lining membrane of the uterus, the formation of the 

 embryo, and the development of the amnion 

 and chorion have been going on simultane- Fig. 268. 



ously ; and soon after the entrance of the 

 egg into the uterine cavity, the chorion is 

 everywhere covered with projecting villosities. 

 These villosities insinuate themselves into the 

 uterine tubules, or between the folds of the 

 decidual surface ; penetrating in this way into 

 little cavities of the uterine mucous mem- 

 brane. When the formation of the decidua 

 reflexa is completed, the chorion has already 

 become uniformly shaggy ; and its villosities, 

 spreading in all directions from its external 

 surface, penetrate everywhere both into the 



. , ,, IMPREGNATED UTERUS, 



decidua vera beneath it and into the decidua showing the connection he- 

 reflexa witn which it is covered. In- this way tween the viiiositiea of the 



c chorion and the decidual mem- 



. , 



the egg becomes entangled with the decidua, 



and cannot be readily separated from it with- 



out rupturing some of the filaments which have grown from its surface, 



and have penetrated the substance of the decidua. The nutritious fluids, 



exuded from the glandular textures of the decidua, are now imbibed by 



the villosities of the chorion ; and a more rapid supply of nourishment 



