Abstract
SUMMARY: Autotransplantation of the ovaries of guinea-pigs to either the uterus or the kidneys caused the degeneration of all luteal and follicular tissue with the exception of the primordial follicles situated in the periphery of the graft. Follicular development then took place and oestrus and ovulation occurred 10–11 days after transplantation. The corpora lutea formed at this ovulation were maintained in a functional state for more than 35 days when the ovaries were transferred to the kidneys but when ovarian grafts were made to the uterus a series of shortened vaginal cycles was observed. These results substantiate the local nature of the luteolytic abilities of the uterus in this species and imply the existence of a uterine luteolytic substance.