CYCLIC CHANGES IN UTERUS AND OVARIES. 9 



Occasionally some edema is present in the surface epithelium 

 and at such places vacuoles are present in the epithelial cells. 



This condition of the uterus may exist notwithstanding the 

 presence of follicles in the ovaries which are near maturity. The 

 latter do, therefore, at least as long as the corpora lutea func- 

 tionate, not produce the changes in the mucosa of the uterus 

 which are characteristic of the first period in the sexual cycle. 



During pregnancy the uterus below or above the insertion of 

 the placenta or in the horn in which there happens to be no 

 embryo shows low cuboidal or low cylindrical epithelium with or 

 without mitoses. There may be some vacuoles in the epithelial 

 cells. There are small narrow coiled glands with low cylindrical 

 epithelium. There is no large connective tissue cell layer present. 

 The nuclei in the connective tissue of the mucosa are small and 

 surrounded by well developed connective tissue fibrils; especially 

 between the gland fundi do we find large connective tissue fibers, 

 while underneath the epithelium the number of connective 

 tissue nuclei is relatively greater and the tissue is less fibrillar. 

 Mitoses occur neither in the glands nor in the connective tissue. 

 It seems that in the earliest stages of pregnancy less than ten 

 days after copulation, there are not any or only exceptional 

 mitoses in the surface epithelium; correspondingly we saw pre- 

 viously that six to ten days after a previous period of heat 

 copulation having been prevented no mitoses were found in 

 the surface epithelium. During the middle or end of pregnancy 

 the uterine mucosa has a similar structure; but there may be 

 present some papillae in the mucosa. The presence of mature, 

 or nearly mature follicles in the ovaries is without influence on 

 the structure of the uterus during pregnancy. 



II. THE SEXUAL CYCLE OF UTERUS AND OVARIES IN GUINEA- 

 PIGS IN WHICH HEAT HAD BEEN OBSERVED BUT 

 COPULATION PREVENTED, is AS FOLLOWS: 



At the period of heat previous to the rupture of the follicles we 

 find the following condition : In the ovaries we find one or more 

 small corpora lutea which are just beginning to degenerate 

 (vacuolization in the periphery). The follicles with exception 

 of the smallest show degeneration of the granulosa. There may 



