FOLLICULAR DEVELOPMENT FROM OVARIAN XENOGRAFTS IN SCID MICE

Cortical slices of either cat or sheep ovaries were grafted under the renal capsules of ovariectomized SCID mice. The grafts became vascular ized and were still surviving with large follicles present at autopsy up to nine months later. As developing follicles undergo atresia durin g the period of ischaemia after ovarian grafting, those found in long- term grafts at autopsy had presumably started to grow from the primord ial stage after transplantation, Some follicles had reached a diameter of 3 mm with a normal antrum and appeared to be cytologically normal, but the latent period for the emergence of antral follicles was short er in cat compared with sheep grafts. Oestradiol production from graft s, as indicated by vaginal comification and plasma measurements collec ted at autopsy, was not constant and circulating concentrations varied among animals, and were sometimes far in excess of the normal physiol ogical range of the host. The vaginal smears never presented cytologic al patterns like those of the normal mouse oestrous cycle, and ovulati on had not occurred in any of the grafts. These results demonstrate th at ovarian xenografts in SCID mice can serve as experimental models fo r investigating follicle development in species in which follicle grow th in vitro and studies of the parent animal are impracticable.