94 THE PHYSIOLOGY OF REPRODUCTION 



cells (that is to say, on this view, what takes place after men- 

 struation is merely a repetition of a process which occurs in the 

 embryo). The new epithelial cells, which are at first flattened, 

 gradually become cubical. Heape's account is thus completely 

 at variance with the descriptions of those authors who hold that 

 in the human female the epithelium is renewed entirely from 

 the torn edges of the old epithehum. Heape states that the 

 process of re-formation commences before "the expulsion of the 

 menstrual clot, and even before the cessation of the flow of 

 blood into the uterine cavity. 



(2) There is still an escape of blood as long as the menstrual 

 clot has within the uterine cavity, but after its expulsion the 

 flow is checked. Heape suggests that the contractions of the 

 uterus which serve to expel the clot may assist in stopping the 

 escape of blood. Probably, also, the growth of the new epithelium 

 helps to stop the haemorrhage. After the growth of the new 

 vessels the flow of blood entirely ceases. 



(3) At the commencement of this stage many of the ex- 

 travasated blood corpuscles are seen lying in intercellular spaces 

 in the stroma. These corpuscles, according to Heape, are drawn 

 again into the circulatory system by becoming enclosed within 

 newly formed capillaries. Heape describes the process as 

 follows : " The protoplasm of the cells bounding these [blood- 

 containing] spaces flattens out, the nuclei of the cells becoming 

 also flattened and elongated, and numerous fine capillary vessels 

 are thus formed, continuous with the deeper parts of the mucosa 

 with large pre-existing capillaries, and so with the circulatory 

 system. 



" These fine capiUaries exist only temporarily. When the 

 blood corpuscles are again drawn into the circulation, and when 

 the mucosa has shrunk, again into its resting condition, the fine 

 capillaries are no longer seen ; but during the time in which 

 the reclaiming process goes on they exist in very large numbers." 

 It should be added that this description of the formation of 

 vessels in the uterine mucosa oi Semnopitheciis and Macacus is 

 in opposition to the usual view regarding the growth of new 

 vessels, which are ordinarily supposed to be only capable of 

 developing as off-shoots from pre-existing ones. 



Heape also describes a recuperation of the old blood-vessels. 



