THE HORMONES IN HUMAN REPRODUCTION 



introduce its technical name at this point, to save printing 

 two words for one every time it is mentioned: endometrium, 

 from Greek endo, within, and metron, the uterus. It is a 

 layer about 5 millimeters (1/5 inch) thick, lining the cavity 

 and therefore applied to the inner surface of the pear-shaped 

 muscular parts of the organ. At the upper end of the uterus 

 it blends with the lining of the oviducts as they enter, at the 

 lower end it continues on to become the lining of the vagina. 

 It looks rather like pink or red velvet, slightly moistened. 

 In most animals it is thrown into delicate folds, but in the 

 human uterus it is relatively smooth. Upon the cells and 

 secretions of this layer the embryo is to depend for every- 

 thing it needs during gestation. 



It is always difficult to convey in nontechnical terms an 

 idea of the finer structure of the tissues of the body. In a 

 book for general readers, microscopical anatomy is like 

 mathematics in books on astronomy or physics — something 

 to be avoided if possible. Yet physiology without cell struc- 

 ture means less than Einstein without calculus. Therefore 

 let us buckle down together for a few pages and try to build 

 up a picture of the cell structure of the endometrium for 

 subsequent use. 



The effort would be much easier if we could sit down to- 

 gether in my laboratory and prepare a specimen as shown 

 in Fig. 12. Taking a preserved human uterus from a jar of 

 formalin, we cut it in two lengthwise with a sharp knife so 

 that we can look into the cavity (Fig. 12, A). Then we cut 

 out a horizontal slab of uterine tissue {B) and from this 

 we detach a little block running down through the endo- 

 metrium into the muscle (C). This we shall place on the 

 table, so that its upper side will be that which formed the 

 surface of the lining, facing the cavity; i.e. like a cube of 

 melon with the rind downward and the pulp upward (Fig. 

 12, C). After we have studied and sketched it under low 

 magnification, we shall cut off a very thin slice (technically 



