DEVELOPMENTAL FAILURE OF SWINE EMBRYOS RESTRICTED TO THE OVIDUCAL ENVIRONMENT

Restriction of embryos to the oviducal environment (tube-locked embryos) does not prevent embryonic development to the early blastocyst stage in mice(Kirby, 1962; Orsini & McLaren, 1967), rabbits (Pincus & Kirsch, 1956; Adams, 1958), rats (Alden, 1942) and sheep (Wintenberger-Torres, 1956), though further development of the tube-locked embryos has not been observed and they degenerate (Adams, 1958; Kirby, 1962; Orsini & McLaren, 1967). Kirby (1962) observed that mouse embryos recovered from the uterus con-tinued to develop when transplanted beneath the kidney capsule; when tube-locked embryos were treated similarly only the trophoblast continued to develop. Kirby (1962) suggested that a `uterine factor ' was required for the development of mouse embryos beyond the blastocyst stage. Recently, Krishnan & Daniel(1967) isolated a specific uterine protein, blastokinin, from rabbit uteri and demonstrated that blastokinin stimulated blastulation and blastocyst expansion in vitro. A similar protein, designated uteroglobin, has also been demonstrated in rabbit uterine secretions by Beier (1968) and Kirchner (1969). Uteroglobin has been demonstrated in rabbit embryo blastocoelic fluid between Days 3 and 9 ofpregnancy (Hamana & Hafez, 1970). This study was designed to determin