human embryos

A human embryo is the developing stage that begins when a sperm fertilizes an egg, forming a single cell with combined genetic material. This cell quickly divides and multiplies, creating a cluster of cells that gradually differentiate into tissues and organs. Over approximately eight weeks, the embryo develops structures such as the heart, brain, and limbs, laying the foundation for the fetus. This process involves complex biological signals that orchestrate growth and specialization, guided by genetic instructions, and marks the beginning of human development from conception to fetal stage.