100 THE PHYSIOLOGY OF REPRODUCTION 



observed. Retterer, 1 who has contributed a short account of the 

 changes in the bitch's uterus, describes the niucosa as growing 

 to three or four times its normal thickness, but this observation 

 has not been confirmed. The growth is accompanied by en- 

 largement and congestion of the capillaries, which at the same 

 time become more numerous. 2 The vessels in the surrounding 

 muscular tissue also tend to enlarge. The epithelium undergoes 



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FIG. 12. Section through procestrous uterine mucosa of dog, showing 

 congested vessels between the glands. (From Marshall and Jolly.) 



no material change so far as seen. In the case of the ferret the 

 uterine cavity is described as becoming markedly reduced in 

 size, while the glands are stated to undergo an appreciable 

 swelling accompanied by an increased secretory activity. 



(3) Period of Destruction. The walls of the stretched blood- 

 vessels break down, and red corpuscles, accompanied by 



1 Retterer, " Sur les Modifications de la Muqnensc Uterine ?i 1'Epoque 

 du Rut," C. R. de la ,S'oc. dc Bid., vol. iv , 1892. 



2 Cf. Retterer. loc. cit. ; also Keiffer, "La Formation Glandulaire de 

 1'Uterus," Annalcs dc In Soc. Mcdiw-Cliirurg. de Brabant 1899; and Bonnet, 

 " Beitriige zur Embryologie des Huudes," Anat. Hcfte, vol. xx., 1902. 



