I. A series of experiments is described in which ovaries from litter sisters at the age of from 8 to 20 weeks old were grafted on to the surface of the kidney of male mice.
II. The grafts were examined at periods varying from 10 to 35 days after operation. It was found that in the majority of cases the graft had retained the typical ovarian structure; in one case corpora lutea were present (35 days after transplantation).
III. It is suggested that the survival of the graft is dependent primarily upon its vascularisation, and secondarily upon the degree of activity of the germinal epithelium.
IV. It is assumed that if the germinal epithelium is unimpaired it proliferates; proliferation occurs first sometime before the 10th day, and continues until the graft has attained the stage at which it was at the time of operation.
V. The original large follicles begin to degenerate soon after transplantation; the medium-sized and small ones develop for a certain period of time, but afterwards also undergo degeneration.
VI. Graafian follicles undergo degeneration at various stages of development.
VII. Interstitial tissue appears to be derived from the follicular cells of the atretic, or more probably of the primary and medium-sized anovular follicles.
VIII. It is concluded that the presence of the testis does not affect the vitality of the ovarian graft.