MEMBRANE DECIDU.E. 375 



It is now well known that the mucous membrane lining 

 the gravid uterus forms what has been called the decidua 

 vera, and that a portion is reflected over the ovum, to form 

 the decidua reflexa. Reichert is of the opinion that the view 

 entertained by most observers, that the fecundated ovum 

 lodges itself in one of the furrows of the hypertrophied 

 membrane and is finally enclosed by an elevation of the walls 

 of the furrow, cannot be sustained. He thinks that the ovum 

 first becomes attached to one of the " islands ; " at the point 

 of attachment, the island does not increase in size as rapidly 

 as at other portions, so that the ovum rests in a cup-shaped 

 depression ; finally, a growth takes place from the margin of 

 this depression, which extends around and encloses the ovum, 

 presenting a spot where the final closure takes place, called 

 the decidual umbilicus. 1 



We have given the recent views of Reichert thus fully, 

 for the reason that they are based upon the study of a re- 

 markably young ovum, and appear to be more exact and def- 

 inite than any observation hitherto recorded ; and we shall 

 adopt this description as representing the early stages of the 

 formation of the membranse deciduoe. 



According to Reichert, the ovum is completely enclosed 

 at the twelfth or the thirteenth day. The mucous membrane 

 lining the uterus becomes the decidua vera, and the border 

 from which the new growth is formed which covers the ovum 

 is the boundary between this and the decidua reflexa. The 

 new growth, springing from this border, envelops the ovum 

 completely, and is called the decidua reflexa; and, in this 

 membrane, there is no trace of the uterine tubules. 



As development advances, a portion of the decidua vera, 

 the description of which we reserve for the present, under- 



1 REICHERT, Beschreibung einer fruhzeitigen menschlichen Frucht im bldschen- 

 formigen Bildungszustande nebst vergleichenden Untersuchungen uber die blds- 

 cJienformigen Friichte der Sdugethiere und des Menschen. Archiv fur Anatomic, 

 Physiologie und wissenschaftliche Medicin, Leipzig, 1873, No. 1, S. 127, et seq. 

 This article has also been published separately in 4o., with illustrations. (Idem, 

 Berlin, 1873, S. 89.) 



