Stage 2 (cleavage)

Stage 2, called cleavage, occurs shortly after fertilization when the single-celled zygote begins dividing into multiple cells. This process involves rapid, successive cell divisions without the embryo growing in size. The resulting cluster of cells, called a morula, resembles a solid ball and prepares for further development. Cleavage increases the number of cells, helping to organize the embryo and set the stage for later stages of growth and differentiation. It is a critical step in transforming the single fertilized egg into a complex, multicellular organism.