when does life begin for an embryo
Week 5: The embryonic period begins. The fifth week of pregnancy, or the third week after conception, marks the beginning of the embryonic period. This is when the baby's brain, spinal cord, heart and other organs begin to form. The embryo is now made of three layers. The top layer â the ectoderm â will give rise to your baby's outermost layer of skin, central and peripheral nervous systems, eyes, inner ears, and many connective tissues.