What is the human embryo?
The human embryo is formed when a sperm penetrates an egg, fertilising it and forming a unique genetic identity. After four days the embryo gains an outer layer of cells which become the placenta, and an inner cell mass which will become the fetus. That minute, growing thing becomes itself and its environment! Over the next 14 days the embryo travels up the fallopian tube to the womb, where it settles in the womb wall and starts to grow. In that time it might divide and become two or even three identical twins/triplets. Normally, about 70% of all embryos never reach the womb. When does life begin?
