92 FORMATION AND STRUCTURE OF THE DECIDUA. 



brane of the unimpregnated human uterus, appears to have never yet been 

 clearly demonstrated, although their appearance immediately after impreg- 

 nation and the existence of them in the unimpregnated uterus of the bitch, 



Fig. 16.* 



and many other animals, renders it highly probable that in the human 

 uterus also they exist previous to impregnation, although of such minute 

 size that they have hitherto escaped detection. 



According to the account furnished by Weber, and that given by the 

 other physiologists who have written on the subject, the mucous membrane 

 of the uterus immediately after conception becomes swollen and soft, the 

 cilia of its epithelial cells disappear (Weber),f its tubular glands and the 

 vascular network occupying the spaces between them increase considerably 

 in size, whilst, as shewn both by Professor Weber and Professor Goodsir,| 

 a substance composed of nucleated cells fills up the inter-follicular spaces 

 in which the bloodvessels are contained. To this inter-follicular substance 

 Professor Goodsir attributes much of the increased thickness of the mucous 

 membrane, and he considers that it plays an important part in the further 

 purposes of the decidua. When thus developed, the mucous membrane 

 of the uterus, according to Professor Goodsir, begins to secrete largely, and 

 the cavity of the uterus is shortly filled with the secreted fluid which con- 

 stitutes the " hydroperione " of Breschet. The portion of this secretion by 

 which the os uteri is plugged up, is composed of elongated epithelial cells ; 

 whilst the portion which immediately surrounds the ovum consists of cells 

 of a spherical form. To these latter cells Professor Goodsir attributes an 

 important office, that, namely, of preparing nutritive material for the ovum 

 by their further development and the production of successive quantities 01 

 new cells. 



It is of these cells also, according to the same observer, that the decidua 

 reflexa is formed, and not, as was formerly supposed, by the ovum protrud- 



* Fig. 16. Section of the lining membrane of a human uterus at the period of com- 

 mencing pregnancy, shewing the arrangement and other peculiarities of the glands d. d. d, 

 with their orifices, a. a. a., on the internal surface of the organ. Twice the natural size. 

 After E. H. Weber. 



t Froriep's N.Notizen, No. 507, p. 1, 1842. 



Anatomical and Pathological Observations, Edinburgh, 1845. 



