1 6 Veterinary Obstetrics 



sheep and goat ; or in varying numbers, as in the carnivora and 

 rodentia. 



It is estimated that the ovaries of a child two years of age 

 are fully developed so far as the new formation of ova is con- 

 cerned. Ovogenesis must cease much earlier in our domestic ani- 

 mals, all of which may reach sexual maturity within one year 

 from birth and are in most ways more mature when born than is 

 the child when two years old. 



In old animals which have ceased to breed or to show sexual 

 desire, the ovaries are much atrophied and contain degenerate ova 

 incapable of fecundation, signifying that the supply of fecunda- 

 ble ova has become exhausted during the span of sexual life. 

 This suggests that any estoppel of ovulation, like pregnancy, 

 where the cycle is longer than that of ovulation, as in all our 

 larger animals, will tend in some degree to conserve the num- 

 ber of ova capable of further development. In harmony with 

 this thought, we find that mares which are regularly bred tend to 

 retain their reproductive powers to a later period in life than 

 those which are not permitted to breed until aged, but here 

 other factors, probably of greater importance, are at work. 



The rupture of the ovisac leaves a lesion which usually be- 

 haves differently according to whether the discharged ovum be- 

 comes impregnated and undergoes development into a fetus or, 

 failing of fecundation, perishes. The ruptured sac becomes filled 

 with lymph, blood or other products of the disturbances of the 

 tissues. Should the ovum perish, the ruptured ovisac tends to 

 heal rapidly, with a faintly yellowish cicatrix, which .soon disap- 

 pears entirely so that no visible trace exists of the ruptured sac. 

 The temporary scar is known as ■Sl false corpus luteum. The per- 

 sistence of a corpus luteum, especially if over size, in a non- 

 pregnant animal, inhibits ovulation and induces sterlity. (See 

 under " Sterility." " Persistent Corpus lyUteum "). 



Should the ovum become fecundated and undergo normal de- 

 velopment, the scar resulting from the ruptured ovisac normally 

 attains greater dimensions, is markedly yellow in color, projects 

 beyond the ovarian surface and persists nearly or up to the time 

 of parturition, and is known as a true corpus luteuvi, We thus 

 note a bond of functional sympathy between the ovary and the 

 fate of a discharged ovum, a harmony shown constantly between 

 the various organs of the reproductive system. An important 



