STUDY OF OVO-IMPLANTATION IN THE HAMSTER, RAT, MOUSE, GUINEA-PIG AND RABBIT IN CLEARED UTERINE TRACTS

Material bleached with hydrogen peroxide and cleared through benzol to benzyl benzoate is of value in study of early im¬ plantation stages. When studied with oblique illumination, opacity identifies the gestational regions in hamster and guinea-pig prior to any gestational swelling, and coincides with the first gestational swelling in mouse and rat. By the clarity of this technique, differential changes in the rat and hamster uterine lumen indicate the site of beginning implantation prior to any obvious opacity, and allow rabbit ova to be localized within the uterus by 4 days and 6 hr after artificial insemination, which is prior to spacing of the eggs along the uterus. The first gestational swelling in the rabbit was at 6 days and 22 hr; opacity appeared at the mesometrial side of the gestational swelling by 7 days and 22 hr. The subsequent development of such opacity in all forms investigated suggests that this is due to the presence of decidua. The exact nature of the substance associated with the opacity is not known but association with glycogen is suggested.