New research offers glimpse into early human development
By LAURA UNGAR (AP) — Scientists have been able to get a rare glimpse into a crucial, early stage of human development by analyzing an embryo in its third week after fertilization — a moment in time that has been difficult to study because of both practical and ethical considerations. European researchers looked at a single embryo that was 16 to 19 days old, donated by a woman who ended her pregnancy.