Rabbit Fetuses Implanted and Developed in the Greater Omentum

The authors encountered rabbit fetuses that developed from fertilized eggs implanted in the peritoneal cavity. A laparotomy of a rabbit that showed no signs of parturition even in the late period of pregnancy 32 days after mating revealed two fetuses suspended from the greater curvature of the stomach. Both fetuses were dead, their body weights were 44 g and 37 g, and their body lengths were 8.0 cm and 7.8 cm. No placenta was present. Blood vessels that ran in the greater omentum communicated with the chorio-allantoic membranes of the two fetuses. Since no corpora lutea were observed in the ovaries, and since no injury was noted in the uterus, this case was judged to be primary ectopic pregnancy caused by migration of fertilized eggs in the peritoneal cavity and their implantation in the greater omentum.