A human embryo has its first heartbeat at the age of three weeks, when the heart of the embryo looks like a tube.
As it begins to beat, it starts the blood circulating through the few blood vessels that have formed around it.
A human embryo has its first heartbeat at the age of three weeks, when the heart of the embryo looks like a tube.
As it begins to beat, it starts the blood circulating through the few blood vessels that have formed around it.