Getty Images/iStockphoto. The embryo models included a placenta, a yolk sac, an outer membrane called the chorionic sac and other cellular structures one would see in human embryos of ...

If scientists could watch an embryo’s cells develop in real time, they might be able to understand, track, and ultimately prevent, the formation of mutations and diseases in human infants ...

Now, for the first time, scientists have captured images and video in real time of these early developmental stages, offering exciting insights into the long-standing "mystery" of human development.

Understanding the early embryo as not-yet-human contributed to widespread tolerance of abortion. This would begin to change only in the Enlightenment. So, the Enlightenment apparently had its flaws.

SNEAK PEEK At 9.5 weeks of pregnancy, a human embryo is almost 16 millimeters long — about the size of a 1-cent euro coin. A new 3-D tool lets users check out (from left) the embryo’s skin ...

Origins The 14-day rule is an ethical line past which cultured human embryos are not to continue developing outside the body. It is protected by law in 12 countries, including the United Kingdom ...

A living human embryo (left) is shown at the eight-cell stage, when it is already undergoing asymmetric cell division (asymmetric cell division in blue, right; artist’s illustration).

Human embryos are more muscle-bound than adult humans, new microscope images cataloging early development show. For instance, at seven weeks of gestation, embryonic hands have about 30 muscles.

The little clump of cells looked almost like a human embryo. Created from stem cells, without eggs, sperm, or a womb, the embryo model had a yolk sac and a proto-placenta, resembling a state that ...

A Japanese scientist plans to insert human cells into rat embryos (pictured). Credit: Science Pictures ltd/SPL. A Japanese stem-cell scientist is the first to receive government support to create ...