An in-vitro system for the fertilization of superovulated rabbit ova recovered from the ovarian surface and from the oviducts was used to study uterine-oviducal relationships in connection with sperm capacitation. Spermatozoa recovered from ligated uterine horns as early as 8 hr after mating were capacitated although they fertilized periovarian ova at a lower level than spermatozoa from control uteri.
In the last decade, a number of factors have been found which aid an in-vitro fertilization system. Replacement of serum by bovine serum albumin (BSA) (Brackett, 1966) and the maintenance of high humidity and prevention of evaporation from culture dishes (Brackett & Williams, 1965) have augmented the earlier work of Chang (1955, 1959) and Bedford & Chang (1962). Using the techniques first described by these workers and some new