336 



HUMAN UTERUS AND FCETAL APPENDAGES. 



appearance, neighbors being often quite dissimilar; nearly all are cuboidal, but 

 some are flattened out; of the former, a number are small with darkly stained 

 nuclei, but the majority of the cells are enlarged, with greatly enlarged hyaline, 

 very refringent nuclei. There are also in many of the gland spaces isolated 

 enlarged cells, which have detached themselves from the wall, and in some cases 

 the detached cells nearly fill the gland cavity, very much as in figure i86. 



The decidual cells of the cavernous layer (Fig. 194, D') are smaller and more 

 crowded than most of those of the compact layer. The largest cells are scat- 

 tered through the compact layer, but are most numerous toward the surface. 

 They extend around the margin of the placenta and have penetrated the chorion, 



in the cellular layer of which they are 

 very numerous ; the immigration im- 

 parts to the chorionic layer in ques- 

 tion somewhat the appearance of a 

 decidual membrane. Misled by this 

 peculiarity, some authors have held 

 this layer to be maternal in origin, 

 and accordingly have described it as 

 a " decidua subchorialis." The de- 

 cidual cells exhibit great variety in 

 their features (Fig, 195). They are 

 nearly all oval discs, so that their 

 outlines differ according as they are 

 seen lying in the tissue turned one 

 way or another ; they vary greatly in 

 size; the larger they are, the more 

 nuclei they contain; the nuclei are 

 usually more or less elongated; the 

 contents of the cell granular. Some of the cells present another type, c; these 

 are more nearly round, are clear and transparent; the nucleus is round, stains 

 lightly, and contains relatively few and small chromatin granules; such cells are 

 most numerous about the placental margin. 



Fig. 195. — Decidual Cells from the Section 



Represented in Fig. 194. 



c, Multinucleate cell ; at a seven blood-corpuscles have 



been drawn in to scale as a measure of size. 



The Human Placenta. 



Specimens of the fresh normal human placenta can be obtained without 

 difficulty from maternity hospitals. The specimen should be thoroughly ex- 

 amined in the fresh state by the student and all the points in the description 

 below verified by him. To make an injected specimen either the starch injection 

 mass or the colored gelatin mass may be used accordingly as it is desired to 



