Editing Ontogeny (section)

=== Cleavage ===
Not long after successful fertilization by sperm, the zygote undergoes many [[Mitosis|mitotic divisions]], which are also non-sexual cell divisions. [[Cleavage (embryo)|Cleavage]] is the process of cell division, so the starting zygote becomes a collection of identical cells which is a morula and contains cells called blastomeres.<ref name="Muhr-2022">{{cite book |last1=Muhr |first1=Jeremy |last2=Arbor |first2=Tafline C. |last3=Ackerman |first3=Kristin M. |title=StatPearls |date=2024 |publisher=StatPearls Publishing |chapter-url=http://www.ncbi.nlm.nih.gov/books/NBK554394/ |chapter=Embryology, Gastrulation |pmid=32119281 }}</ref> Cleavage prepares the zygote to become an embryo, which is from 2 weeks to 8 weeks after conception (fertilization) in humans.<ref>{{cite book |last1=Gilbert |first1=Scott F. |title=Developmental Biology |edition=6th |date=2000 |publisher=Sinauer Associates |chapter-url=https://www.ncbi.nlm.nih.gov/books/NBK9992/ |chapter=An Introduction to Early Developmental Processes }}</ref>
[[File:Figure_27_01_03.jpg|thumb|590x590px|Process of zygote to gastrula in development]]