Cleavage

Definition

Cleavage is the series of rapid mitotic cell divisions that follow fertilization, leading to the formation of a multicellular embryo. These divisions result in smaller cells called blastomeres and do not involve growth between divisions.

5 Must Know Facts For Your Next Test

1. Cleavage typically results in the formation of a morula, which is a solid ball of cells.
2. The pattern of cleavage can vary significantly among different animal species.
3. Cleavage increases the number of cells without an increase in the overall volume of the embryo.
4. Types of cleavage include radial, spiral, bilateral, and rotational, depending on how cells divide and organize themselves.
5. Cleavage is influenced by factors such as yolk distribution and genetic regulation.

Review Questions

• What is the primary purpose of cleavage in early embryonic development?
• How does cleavage differ from typical cell division?
• Name and describe one type of cleavage pattern.

Related terms

Blastomere: The smaller cells formed during the process of cleavage.

Morula:

A solid ball of cells resulting from several rounds of cleavage.

Blastula: The stage following morula where cells form a hollow sphere around a fluid-filled cavity called the blastocoel.