What is the cleavage stage in embryonic development?

The cleavage stage in embryonic development refers to the phase of rapid cell division of the zygote after fertilization. During this stage, the single-celled zygote divides repeatedly to form multiple smaller cells called blastomeres. This occurs without the embryo growing in size, as the divisions are focused on increasing the number of cells while maintaining the same overall volume.

This process is crucial as it sets the stage for further development, leading to the formation of a multicellular structure known as the blastula, which eventually will undergo implantation and further differentiation into various tissue types. By understanding that cleavage is characterized by these rapid divisions, it's clear why this answer accurately defines the cleavage stage within the context of embryonic development.