Editing Cell type (section)

==Multicellular organisms==
All higher [[multicellular organism|multicellular]] [[organism]]s contain cells specialised for different functions. Most distinct cell types arise from a single [[totipotent]] cell that [[Cellular differentiation|differentiates]] into hundreds of different cell types during the course of [[Development (biology)|development]]. Differentiation of cells is driven by different environmental cues (such as cell–cell interaction) and intrinsic differences (such as those caused by the uneven distribution of [[molecule]]s during [[cell division|division]]). [[Multicellular organisms]] are composed of cells that fall into two fundamental types: [[germ cell]]s and [[somatic cell]]s. During development, somatic cells will become more specialized and form the three primary [[germ layer]]s: [[ectoderm]], [[mesoderm]], and [[endoderm]]. After formation of the three [[germ layer]]s, cells will continue to specialize until they reach a terminally differentiated state that is much more resistant to changes in cell type than its [[Progenitor cell|progenitors]].

The simplest organism considered to have well defined cell types are some [[Volvocaceae|volvoceans]], such as ''[[Volvox carteri]]'', in which each organism is composed of distinct and interdependent cell populations, some somatic and some reproductive.<ref>{{Cite book |last=Gilbert |first=Scott F. |title=Developmental biology |date=1997 |publisher=Sinauer |isbn=978-0-87893-244-3 |edition=5th |location=Sunderland (Mass.) |pages=17 |language=en}}</ref>