Pub. date: 2008 | Online Pub. Date: September 15, 2008 | DOI: 10.4135/9781412963954 | Print ISBN: 9781412959087 | Online ISBN: 9781412963954| Publisher:SAGE Publications, Inc.About this encyclopedia
Division Types (Symmetrical and Asymmetrical)
TWO DISTINCT TYPES of cell division have been observed during the development of both invertebrates and vertebrates: symmetrical and asymmetrical cell divisions. An asymmetric cell division produces two daughter cells with different properties. This is in contrast to symmetric cell divisions, which give rise to equivalent daughter cells. Notably, stem cells divide asymmetrically to give rise to two distinct daughter cells: one copy of themselves and one cell programmed to differentiate into another cell type. Animals are made up of a vast number of distinct cell types. During development, these cell types are generated from a single cell, the zygote. Asymmetric divisions contribute to this expansion in cell type diversity by making two types of cells from one. For example, it is thought that many of the cells in the central nervous system derive from asymmetric divisions. Cells may divide asymmetrically to produce two novel cells at the expense of ...