STEKILITY 229 



STERILITY 



It would seem that sterility in the female must depend upon one of 

 several causes. The ovaries may be incapable of forming eggs, or the eggs 

 when formed are defective and incapable of fertilization. The ovaries, on 

 the other hand, may be functionally perfect, but owing to some obstructive 

 condition of the Fallopian tubes or oviducts they fail to reach the uterus. 

 Again, a perfectly healthy ovum may be impregnated and safely conveyed 

 to the womb, but unless that organ is in a normal condition it may die, 

 conception would not take place, and the mare would as a consequence fail 

 to breed. 



The writer has known several instances where the entire structure of 

 the egg-forming glands have been destroyed by the growth and expansion 

 within them of cysts or bladder-like formations (fig. 527), and other cases 

 where the glands have been rendered functionally useless by the develop- 

 ment within them and round them of malignant tumours. The Fallopian 

 tubes may be rendered impervious by pressure from without, or by 

 thickening of the membrane lining them, or by morbid growths within 

 them or upon them. Mares which have passed through a period of diffi- 

 cult foaling not unfrequently become sterile owing to the Fallopian tubes 

 getting blocked up by inflammatory products, or so far thickened as to 

 obliterate the passage and prevent the ovum from reaching the uterus. 



However perfect the ovaries or oviducts may be, impregnation cannot 

 take place unless the semen of the male gains access to the uterus, for 

 which purpose it is necessary that the entrance thereto should be open to 

 receive it. 



Obstruction at this point is not unfrequently the cause of sterility in 

 mares, either as the result of a twist of the neck of the uterus, or a thicken- 

 ing of its walls, or disease of the mucous membrane, any one of which may 

 obstruct the passage and prevent the entrance of the sperm element into 

 the womb. 



From these considerations it will be seen that the possibility of restor- 

 ing fruitfulness in the sterile mare will depend upon the nature of the cause 

 to which the sterility is due. Of these some are amenable to treatment, 

 but others are altogether incapable of being removed. While it would be 

 impossible to restore the function of an ovary or egg-gland whose structure 

 had been broken up and absorbed by the growth of cysts or some other 

 formation within it, it might not be difficult to remove or overcome an 

 obstruction in the neck or mouth of the uterus, or, in some cases, to restore 

 its lining membrane to a normal condition. 



