16 LEO LOEB. 



have not yet advanced to the last stage of atresia. There are 

 mature follicles present. The periphery of the corpora lutea 

 show some slight vacuolization. The connective tissue of the 

 uterine mucosa is at this period very edematous, the edematous 

 fluid may raise the surface epithelium. The connective tissue 

 nuclei are very small. The mucosa and also the muscularis of 

 the uterus are thin. The epithelium of the surface and of the 

 gland ducts is low cuboidal or low cylindrical. This is perhaps 

 partly due to the pressure of the underlying edematous fluid. 

 Where the connective tissue is very edematous, the overlying 

 epithelial cells may also be somewhat edematous and vacuolar. 

 At some places the epithelium of the surface and gland ducts is 

 somewhat higher. Some mitoses are present in epithelial cells 

 of the surface and at the entrance of the gland ducts. Ex- 

 ceptionally a mitosis may be found in a gland duct. 



We see, therefore, that from the fourteenth day on, mitoses 

 reappear in the surface epithelium of the uterine mucosa. If we 

 compare the cyclic changes in the uterus in cases in which copu- 

 lation took place and in which only the heat was observed, but 

 copulation had been prevented, we find the following: 



A few hours after copulation, the leucocytes begin to migrate 

 in large numbers from the connective tissue of the mucosa through 

 the surface epithelium into the lumen of the uterus. Here they 

 collect in such large numbers eight hours after copulation that its 

 contents may be like an abscess. 



These leucocytes exert an injurious influence on the surface 

 epithelium which is therefore after copulation very much earlier 

 and very much more strongly injured than if copulation has been 

 prevented. The epithelium of the gland ducts may also suffer. 

 We find, a few hours after copulation, spermatozoa which may 

 be agglutinated in the lumen of the uterus and also in the gland 

 lumen. The same large number of polynuclear leucocytes is 

 still present during the first twenty-four hours after copulation; 

 they have however mostly disappeared two days after copulation. 

 At that time the condition of the uterus is very similar in animals 

 in which copulation took place and in which copulation had been 

 prevented. A few leucocytes can also be seen in the uterus of 

 animals in which copulation had been prevented. In such 



