Endoreduplication

Endoreduplication is the duplication of the genome without mitosis. Endoreduplication is a common process in eukaryotes and results in an increase in the nuclear DNA content, permitting amplification of the genome of specialized cells. Moreover, the increase in the ploidy level correlates with an increase in nuclear volume and cell size, suggesting that elevated nuclear DNA content is required to maintain larger cells. In animals, endoreduplication is most frequent in Appendicularia, where endoreduplicated epithelial cells are used to produce feeding structures, and in arthropods, where the highest value of the endopolyploidy occur in the Malpighian tubules and salivary glands of various dipters. In mammals, endopolyploidy is rare and evident only in the trophoblast, decidua and myocardial cells. In contrast, endoreduplication is widespread in plants, particularly in angiosperms, and may occur in any cell types except the gametes, the meristematic and guard cells. The constant tissue-specific pattern of endopolyploidy in different organs suggest that endoreduplication cycles in plants constitute an essential part of the developmental programmes that are necessary for differentiation and for specialized function of given cells and tissues.