Fertilised egg i.e., zygote divides and redivides and forms a ball of cells. This is a kind of embryo and it reaches the ** and gets attached to the wall of the **. This fixing of embryo to the ** is called implantation. Now the embryo undergoes a process “specialisation of cells’’. It leads to the formation of different parts of the body. This process is called differentiation. It leads to the formation of various tissues and other organs and thus organ systems are formed. Organ system lead to the formation of an individual. Thus the zygote forms an embryo, it forms a baby and it forms an *****.
