Reproduction in rabbits after excision of the oviductal isthmus, ampullary-isthmic junction, and uteroisthmic junction.

The effect of total deletion of the isthmus, including the ampullary-isthmic junction and the uteroisthmic junction, upon reproduction was determined in 21 rabbits. None became pregnant on the side lacking isthmus, whereas all became pregnant on the intact control side. Eight does were studied using in vivo and in vitro techniques at 18 to 20, 64 to 65, and 136 to 137 hours after mating. Spermatozoa fertilized the ova, with evidence of polyspermy. However, the modified oviduct did not transport fertilized ova into the uterus at the normal time. Furthermore, degeneration was noted from the morula stage onwards. We conclude that the rabbit ova can neither develop normally past the morula stage nor enter the uterus at the normal time in a recognizable form in the total absence of isthmus, and infertility results.