Summary
Rapid cell divisions of the early embryo without growth, producing a ball of smaller cells.
In depth
Divisions are fast with little growth, so cells (blastomeres) become smaller. At around 16 cells it is a morula; compaction occurs. Yolk content affects cleavage pattern: holoblastic in mammals and frogs, meroblastic in birds.
Cell cycles lack gap phases, so cleavage is fast. The cytoplasm is partitioned unequally in some species, creating differences in determinants. In mammals the zygotic genome is switched on early.
Common mistake: the embryo does not grow in size during cleavage; it only subdivides.
Frequently asked questions
What is Cleavage?
Rapid cell divisions of the early embryo without growth, producing a ball of smaller cells.
Which area of biology covers Cleavage, and how advanced is it?
Cleavage is one of the 54 topics in Developmental Biology. It is rated Beginner, so it suits learners who are starting out in biology. Related topics in this area include Zygote, Embryo, Twins.
Can you give an example of Cleavage?
Human cleavage is slow, about one division per day.
What should I learn before Cleavage?
Cleavage is a Beginner topic, so no earlier topic is required. Other Beginner topics in Developmental Biology that pair well with it include Fertilisation, Zygote, Embryo.
What topics are related to Cleavage?
The closest topics to Cleavage are Zygote, Embryo, Twins, Totipotency. Comparing them side by side is a good way to see how the ideas connect.
How can I check that I understand Cleavage?
Read the summary and the in-depth section, then use the quick check on the interactive lesson for Cleavage. To practise the whole of Developmental Biology, use the Developmental Biology quiz.
How is Cleavage different from Zygote?
Cleavage: Rapid cell divisions of the early embryo without growth, producing a ball of smaller cells. Zygote: The single cell formed at fertilisation that divides to become an embryo. Read both side by side and note what each one explains.
What is a common mistake about Cleavage?
The embryo does not grow in size during cleavage; it only subdivides.
How should I study Cleavage step by step?
First, read the summary and write the definition in your own words. Second, read the in-depth section and note any example. Third, compare it with Zygote and explain the difference aloud. Finally, take the Developmental Biology quiz and come back to this page for any question you miss.