DECIDUA REFLEX A OF FIRST STAGE. 



349 



cells are connected. Later on the decidual cells acquire smoother and more rounded 

 outlines, and appear to lose altogether their connections with one another. In the 

 cavernous layer there are no decidual cells. 



Decidua Reflexa of the First Stage. 



The decidua reflexa may be preserved in Zenker's fluid, Parker's fluid, or picro- 

 sulphuric acid. It should be hardened with the portions of the chorion and cho- 

 rionic villi adherent to it. It may be im- 

 bedded in celloidin and the sections stained 

 with alum hematoxylin and eosin, with 

 Beale's carmine, or with a so-called fibrin 

 stain. 



As stated above (page 343), the pres- 

 ence of the decidua reflexa distinguishes 

 the first stage of pregnancy from the 

 second, in which the reflexa is absent, 

 having disappeared by degeneration and 

 absorption. To observe this process of the 

 disappearance of the reflexa, membranes 

 from the second and third months should 

 be examined. 



Section of Decidua Reflexa of Two 

 Months. At this time the reflexa starts 

 from the edge of the placental area as a 

 membrane of considerable thickness, but it 

 rapidly thins out, the very thinnest point 

 being opposite the placenta. Examination 

 of sections shows that the entire reflexa is 

 undergoing degeneration which is found to 

 be more advanced the more remote the 

 part examined is from the placenta. The 

 chorion laeve lies very near the reflexa, being 

 separated only by the villi, which are already 

 very much altered by degeneration. In the 

 region halfway between the base and the 



apex of the reflexa the tissue (Fig. 232) shows only vague traces of its original 

 structure. Only here and there can a distinct cell with its nucleus be made out. 

 Most of the cells have broken down and fused into irregular hyaline masses with- 

 out organization. Ramifying through the fused detritus appear strands and lines, 

 which are more darkly stained by both carmine and hematoxylin. On account of 

 their fibrous appearance, these strands are often spoken of as fibrin, although they 

 are presumably not the same as the true fibrin from the blood. The fibrin is much 



FIG. 232. SECTION OF HUMAN DECIDUA REFLEXA 

 AT Two MONTHS. 



