摘要Four transplant studies are described that focus on fertilisation and early development or the progression of unfertilised oocytes (eggs) in the oviduct.(1) Pig eggs transplanted from ovulations induced during the luteal phase of the estrous cycle were fertilised in the oviducts of inseminated recipient animals in estrus.By contrast,pig eggs from donors in estrus became highly polyspermic when transplanted to the oviducts of animals force-mated during the luteal phase.(2) Pig embryos at the stage of hatched blastocysts (days 7 and 8) could be transplanted successfully to synchronous recipients and full embryonic development demonstrated to between days 19 and 23of pregnancy.Thus,the exposed trophectoderm of developing embryos could withstand the physical manipulation of recovery and transplantation,and the lifespan of corpora lutea in the unmated recipients could be prolonged by transfer of day 7 and 8 blastocysts.(3) Bovine oocytes aspirated from 2 to 6 mm diameter Graafian follicles and matured in vitro were fertilized normally in the oviducts of inseminated recipient heifers,demonstrating the potential of slaughterhouse ovaries for the generation of embryos.(4)Transplanting equine eggs to a pig oviduct,in which egg descent to the uterus requires only 46 to 48 h,did not reveal a retarded progress of degenerating unfertilised horse eggs,suggesting the involvement of nonphysical factors in equine embryo progression to the uterus.Prostaglandins of embryonic origin are now known to be a key.A final section examines the postovulatory role of ovarian follicular cells on the secretory activity of the oviductal epithelium.