100 STUDIES ON PATHOLOGIC OVA. 



to gain access to the stroma of the villi. Indeed, the only invasion of the stroma 

 which I have ever seen in preserved villi is due to invaginations of and extensions 

 from the Langhans layer, for the presence of large numbers of Hofbauer cells hardly 

 can be regarded as an invasion, even if these cells themselves are not fixed in 

 position. 



Besides lytic and degenerate changes due to retention or putrefaction, the 

 occurrence of Hofbauer cells and other appearances suggesting tissue-cultures, 

 thickening of the amnion and chorion was also frequently present. Amniotic 

 villi and fusion of adjacent amniotic folds were seen quite frequently, but the 

 rarest of all changes encountered were such strange appearances on the surface 

 of the amnion as represented in figures 73 and 74. As indicated by the accom- 

 panying scales, both of these chorionic vesicles were small. Upon microscopic 

 examination of these amnions it was seen that the hummocky appearance was 

 due to local thickenings formed by increase in the connective tissue of the amnion. 

 The amniotic epithelium was never found to be involved in these thickenings, and 

 since only two specimens were observed I am at a loss for an explanation of this 

 peculiar condition. 



If the condition of the uterine mucosa at the time of implantation of the 

 impregnated ovum may show variations in structure at all comparable to those 

 frequently seen in the deciduse accompanying abortuses, then it is easily conceiva- 

 ble that the fate of the conceptus may be determined by the structure of the 

 implantation site. Not infrequently a small area of the decidua surrounding an 

 abortus shows all the transitions represented in figures 75 to 77. Figure 75 shows 

 the fine, large, clear, polygonal decidual cells slightly infiltrated and hence rather 

 homogeneous in appearance. Figure 76 shows considerable infiltration and autol- 

 ysis, but there are marked changes in the cell-form which remind one of the con- 

 dition of the post-menstrual endometrium, as described by Hitschmann and Adler 

 (1908). The decidual cells in these areas seem to take on the character of fibro- 

 blasts, and this characteristic is brought out still more in figure 77. In some 

 specimens the decidua is composed of a decidedly fibrous mass, which reminds one 

 at once of connective tissue. I do not know how far these changes of fibrosis may 

 be present before implantation occurs or before placental differentiation has 

 taken place; but if at all pronounced they can scarcely fail to affect profoundly 

 the nutrition and growth of the conceptus. 



It also may be urged that fibrosis of the decidua is but an effect of the death 

 and retention of the conceptus rather than of pathologic conditions pre-existent 

 to the advent of pregnancy, but the many instances in which the decidua is very 

 degenerate and also infiltrated would seem to argue against such an assumption. 

 Besides, many deciduse surrounding specimens retained for a considerable period 

 of time do not show comparable changes, and (as Orloff, Iwanoff, and L. Fraenkel 

 have shown) restoration of the mucosa actually may begin before the conceptus is 

 expelled from the uterus. In the few cases I have seen of partial regeneration of 

 the mucosa, the decidua was not markedly fibrous. Infiltration of the decidua 

 may possibly arise after the death of a conceptus, but that it is frequently present 



