CHANGES IN THE NON-PREGNANT UTERUS 101 



leucocytes, become extravasated throughout the stroma. Some 

 of the vessels, however, remain intact. The breaking down of 

 vessels appears to occur fairly uniformly throughout the stroma 

 instead of being restricted to any particular portion. The 

 extravasated blood for the most part collects immediately below 

 the superficial epithelium, but it is not aggregated in large 

 lacuna-like spaces, such as Heape has described in the monkey. 





polyrr/ }*jfa 



V*!? * * * * * * 



ex. bl. 



w 



FIG. 13. Section through prooestrous uterine mucosa o dog. (From 



Marshall and Jolly.) 



ex. bl., Extravasated blood corpuscles ; polym., polymorph ; sec., cells 

 probably indicating secretory activity. 



These " sub-epithelial hsematomata " have been noticed espe- 

 cially in the procestrous bitch. The walls of the vessels in the 

 muscular layers do not give way. 



Eventually the extravasated blood corpuscles (or, at any 

 rate, the majority of them) make their way into the cavity of 

 the uterus, and thence to the vagina, where external bleeding is 

 observed. This is especially noticeable in the case of the bitch, 

 with which, as already mentioned, external bleeding may last 

 for as long as ten days. The bleeding is accompanied by an 

 increase in the mucous secretion. At about the same stage 



