About 32 days after ovulation, the embryo is about 1/4 inch in length. At this stage the heart begins to beat and the eyes begin to form. The embryo has open lens pits, a pair of depressions in the outer layer of the embryonic head where the eye lens develops. The two depressions are beginning to enclose to form the eyes. The buds that will become the limbs are elongated and tapering. Photo by Bradley R. Smith © 2009.