Age Changes in the Ovary 151 



could be attempted. Foa (1900, 1901) transplanted newborn 

 rabbit ovaries into rabbits of different ages. One of his 

 experimental groups, in which twelve to eighteen-month-old 

 rabbits were used as hosts, demonstrated for the first time 

 that transplantation into a mature environment accelerates 

 the maturation of a young ovary. This group, however, only 

 contained three experiments of which two gave positive 

 results. In another group the hosts were five to six years old 

 and the newborn ovary never survived the transplantation. 

 Conversely, Lipschutz (1925) showed that the transplantation 

 of mature ovaries failed to induce rapid feminization if the 

 host guineapigs were prepubertal. Other experiments, which 

 indicate that ovaries of newborn animals develop precociously 

 when grafted into older animals, have also been described 

 by Lipschutz (1925), Del Castillo (1929), Engle (1929) and 

 Pfeififer (1934). Goodman (1934), May (1940) and Dunham, 

 Watts and Adair (1941) showed that immature ovaries which 

 are implanted into the anterior chamber of the eye of adult 

 male and female rats of the same inbred strain also develop 

 more rapidly than normal. CEstrous cycles are restored after 

 only a very slightly longer delay (thirteen to seventeen days) 

 than follows the grafting of adult ovaries (seven to fourteen 

 days). In many of these experiments there is some doubt 

 about the final result and Del Castillo, for instance, believes 

 that the oestrous cycles which appear in adult spayed animals 

 grafted with young ovaries, soon disappear again. He could 

 find no trace of the grafts at autopsy. 



Hertz and Hisaw (1934), whose work on the sensitivity of 

 young ovaries to gonadotrophin has already been mentioned, 

 grafted four-week-old ovaries under the renal capsule of 

 twelve to fourteen-week-old rabbits. Ten days later they 

 began treatment with gonadotrophin. In four experiments in 

 which the grafts took successfully the hosts' ovaries responded 

 normally, but the grafts were not affected. They interpreted 

 this observation to indicate that the failure of the very young 

 gonad to respond resided specifically in the ovary and was 

 not influenced by conditions in the rest of the intact animal. 



