Search

This article reports that human chorionic gonadotropin is a widely studied embryonic secretion, but its specific function and the stage of embryonic development when its secretion begins are unknown. It has been found in plasma and urine as early as 6 to 9 days after conception, that is, very soon after attachment of the blastocyst to the endometrium. In the current procedure a maximum of three embryos are replaced in the mother, and the others are observed for their growth in vitro. Surrounding cumulus cells were removed from the oocytes on the morning after they were exposed to spermatozoa and the fertilized eggs were transferred to droplets of medium identical to that described above but containing 15 percent maternal serum. The embryo from patient 1 was then transferred in a droplet containing modified Earle's solution with 15 percent maternal serum and the embryo from patient 2 was treated in the same manner, except the concentration of serum was 25 percent. Culture was continued for a further 100 hours before the outgrowths were fixed for histological analysis.