Reduced blood supply to the uterus as a cause for early embryonic death in the mouse

Limitation of blood supply to the developing embryo of the mouse was accomplished by electrocoagulation of the blood within the vessels supplying one horn of the uterus. When blockage of both the uterine artery and vein and the secondary vessels was performed before mating, 35.6% of the ova, as represented by corpora lutea (CL), were present as implantation sites at autopsy, ten days post coitum (ten days); 91.1% of the ova (CL) were present as implantation sites on the control side. During the time between electrocoagulation and mating (average, 8.3 days), some reestablishment of circulation had usually occurred. When unilateral coagulation was performed at one day and at five days, 2.6% and 14.6% of the ova, respectively, subsequently formed implantation sites. When alternate secondary branches of the uterine blood supply to one horn were coagulated at one day, 40.6% of the ova resulted in implantation sites at ten days. Tertiary arborizations of undisturbed branches appear to revascularize portions of the horn to which the blood supply had been coagulated. When blood supply to the ovarian, middle or cervical portions of the uterus was blocked at one day, 6.3%, 42.9% and 14.3% of the ova, respectively, formed implantation sites. It is suggested that the blood supply to the ovarian portion of the uterus is critical to the descending embryo. There was a significant correlation between the number of secondary vessels and the number of implantation sites in all intact uterine horns.