Editing Ploidy (section)

===Tissue-specific polyploidy===
In large multicellular organisms, variations in ploidy level between different tissues, organs, or cell lineages are common. Because the chromosome number is generally reduced only by the specialized process of meiosis, the somatic cells of the body inherit and maintain the chromosome number of the zygote by mitosis. However, in many situations somatic cells double their copy number by means of [[endoreduplication]] as an aspect of [[cellular differentiation]]. For example, the hearts of two-year-old human children contain 85% diploid and 15% tetraploid nuclei, but by 12 years of age the proportions become approximately equal, and adults examined contained 27% diploid, 71% tetraploid and 2% octaploid nuclei.<ref>{{cite book |url=https://books.google.com/books?id=VhLOSt1bq-wC&pg=PA234 |title=The Development and Regenerative Potential of Cardiac Muscle |author1=John O. Oberpriller |author2=A Mauro |publisher=Taylor&Francis|isbn=9783718605187 |year=1991 }}</ref>