[A study of morphopathological changes in the ovary caused by parabiotic union in rats]

Male and female Wistar rats from the same brood were joined parabiotically and histopathological changes in the ovary of the reactor were observed from the 8th to the 41st week. Only one tumor, a granulosa cell tumor appearing in the 28th week, was seen to form. Histogenetically, it appeared to have arisen from the follicular granulosa cells. In many cases, stromal luteinization progressed until the entire ovary appeared to consist of luteinized tissue, but in no case were tumor features noted. Changes followed the same process as in autotransplantation of the ovary into the spleen or as in irradiation; eventual tumor formation was judged likely from the observations in some cases. The cause of the extremely low rate of tumor formation in this experiment is thought to be inhibition of gonadotropin production by estrogen transferred from reactor to partner via capillary communicating branches.