9 8 



THE PHYSIOLOGY OF REPRODUCTION 



during oestrus are fertilised. During pseudo-pregnancy the uterus 

 undergoes growth changes which relate chiefly to the blood-vessels 

 and glands of the mucosa. 1 These increase in size, the whole organ 

 assuming a histological appearance of great activity. Three weeks 

 after the beginning of proosstrous bleeding, the epithelial cells lining 

 the crypts and glands are columnar, and this condition remains until 

 about the end of the fifth week when the cells become cubical. The 



FIG. 17. Section through mucosa of dog during a late stage of recuperation. 

 (From Marshall and Jolly.) 



bl. v., Blood-vessel ; sp., spermatozoa in cavity of gland. 



lumina of the glands contain a colloidal secretion and in the later 

 stages remains of desquamated epithelial cells. About the eighth 

 or ninth week from the beginning of " heat " the capillaries begin 

 to break down and corpuscles are freely extravasated in the 



1 Marshall and Hainan, "On the Post-CEstrous Changes occurring in the 

 Generative Organs and Mammary Glands of the Non-Pregnant Bog," Proc. 

 Ray. Soc., B., vol. Ixxxix., 1917. Cf. Keller, "Uber den Bau des Endometi'iums 

 beim Hunde," Anat. ffefte, vol. cxviii., 1909; and Drahn, "Die anatomischen 

 Veranderungen am Geschlechtsapparat unserer Haustiere bei der Bi-unst mit 

 besonderer Beriicksichtigung der Hundin," Liang. -Diss. zu Hannover, Berlin, 

 1913. This memoir contains interesting comparative data. 



