Final answer:
Cleavage in embryonic development refers to mitotic cell divisions resulting in smaller cells called blastomeres, with little to no growth between divisions, maintaining the total volume of the embryo.
Step-by-step explanation:
Cleavage as part of embryonic development is distinctive because it involves cell division by mitosis with little or no growth between successive divisions. This specific aspect of embryogenesis starts with a single-celled zygote that undergoes multiple mitotic divisions, referred to as cleavage. This process results in smaller and smaller cells called blastomeres without an increase in the total volume or mass of the embryo.
Three such divisions transform the zygote into an eight-celled structure, and after additional divisions and rearrangements, a solid ball of cells called a morula is formed. This eventually becomes a hollow structure known as the blastula, which is characterized by a fluid-filled cavity surrounded by cells. The cleavage divisions are critical in subdividing the cytoplasm of the original egg into multiple blastomeres while maintaining the total volume of the conceptus.