THE MUCOUS MEMBRANE ELEVATION. 35 



extremity and has a gland passing through its entire length. 

 This gland in its middle portion is dilated and folded and lined 

 in its entirety with perfectly preserved cuboidal epithelium. 



Gradually this hill like elevation becomes more rounded (Fig. 

 2. b. h.) with a sharp groove on its right side. This shape is 

 maintained through almost all of the sections until section 160 

 is reached, where it takes on a more club shaped appearance. 

 The furrow to its right has become somewhat shallower and now 

 runs perpendicular. 



We might be led to believe that this elevation was brought 

 about by the embedding of the ovum, but the further examination 

 of the specimen will show that the mound is only the marginal 

 elevation of a mucous membrane field, lying just above a groove, 

 through which the ovum has bored its way. 



This ovum, like the ovule of Peters, in all probability has en- 

 tirely sunk into the mucous membrane, so that we also find in 

 this case the ovular chamber completely surrounded by a de- 

 cidua vera which extends up into the cap which covers the top 

 of the ovum and protrudes into the uterine cavity. Besides this 

 decidual tissue the cap contains the fibrinous cover consisting 

 of two layers or two flat portions, while in Peters' case the clos- 

 ure of the small opening on the top is formed by the fibrin lid 

 alone, in this case the nidus of the ovum represents a com- 

 pletely closed cavity which on its top carries the fibrinous cover. 



In investigating the histologic structure of this mucous mem- 

 brane elevation our attention is at once drawn to the decidual 

 tissue, the glands and the blood vessels, the ovular chamber and 

 its fibrin cover. Since the two last named structures will be con- 

 sidered in the next chapter, the enveloping tissue alone shall here 

 be described. 



It is probably unnecessary to state that the younger the ovum, 

 the better will be the opportunity of studying the origin of cer- 

 tain structures such as the decidual cells, the syncytium, the inter- 

 villous spaces, etc. 



If any doubt has still existed concerning the fact that the de- 

 cidual cells are nothing else but hypertrophied connective tissue 

 cells of the uterine muscosa and have nothing to do with the 

 leucocytes, this doubt is now dispelled by this specimen. 



The mucous membrane enveloping the ovum is swollen and 

 appears edematous. Large connective tissue cells with long pro- 

 cesses form a delicate network. These cells contain large nuclei 

 which in some cases completely fill the cell body. Some cells 

 have two nuclei, and like Peters (1. c. page 15.), I was able to 

 observe signs of karyokinesis in them. 



