A cell type is a classification used to distinguish between morphologically or phenotypically distinct cell forms within a species. A multicellular organism may contain a number of widely differing and specialized cell types, such as muscle cells and skin cells in humans, that differ both in appearance and function yet are genetically identical. Cells are able to be of the same genotype, but different cell type due to the differential regulation of the genes they contain. Classification of a specific cell type is often done through the use of microscopy (such as those from the cluster of differentiation family that are commonly used for this purpose in immunology). Recent developments in single cell RNA sequencing facilitated classification of cell types based on shared gene expression patterns. This has led to the discovery of many new cell types in e.g. mouse cortex, hippocampus, dorsal root ganglion and spinal cord.
All higher multicellular organisms contain cells specialised for different functions. Most distinct cell types arise from a single totipotent cell that differentiates into hundreds of different cell types during the course of 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 molecules during division). Multicellular organisms are composed of cells that fall into two fundamental types: germ cells and somatic cells. During development, somatic cells will become more specialized and form the three primary germ layers: ectoderm, mesoderm, and endoderm. After formation of the three germ layers, cells will continue to specialize until they reach a terminally differentiated state that is much more resistant to changes in cell type than its progenitors.
Even though the concept of cell type is widely used, specialists still discuss the exact definition of what constitutes a cell types.
- Zeisel A, Muñoz-Manchado AB, Codeluppi S, Lönnerberg P, La Manno G, Juréus A, Marques S, Munguba H, He L, Betsholtz C, Rolny C, Castelo-Branco G, Hjerling-Leffler J, Linnarsson S (March 2015). "Brain structure. Cell types in the mouse cortex and hippocampus revealed by single-cell RNA-seq". Science. 347 (6226): 1138–42. doi:10.1126/science.aaa1934. PMID 25700174.
- Usoskin D, Furlan A, Islam S, Abdo H, Lönnerberg P, Lou D, Hjerling-Leffler J, Haeggström J, Kharchenko O, Kharchenko PV, Linnarsson S, Ernfors P (January 2015). "Unbiased classification of sensory neuron types by large-scale single-cell RNA sequencing". Nature Neuroscience. 18 (1): 145–53. doi:10.1038/nn.3881. PMID 25420068.
- Häring M, Zeisel A, Hochgerner H, Rinwa P, Jakobsson JE, Lönnerberg P, La Manno G, Sharma N, Borgius L, Kiehn O, Lagerström MC, Linnarsson S, Ernfors P (June 2018). "Neuronal atlas of the dorsal horn defines its architecture and links sensory input to transcriptional cell types". Nature Neuroscience. 21 (6): 869–880. doi:10.1038/s41593-018-0141-1. PMID 29686262.
- Margulis L, Chapman MJ (2009). Kingdoms and Domains: An Illustrated Guide to the Phyla of Life on Earth (4th ed.). Amsterdam: Academic Press/Elsevier. p. 116.
- "What Is Your Conceptual Definition of "Cell Type" in the Context of a Mature Organism?". Cell Systems. 4 (3): 255–259. 22 March 2017. doi:10.1016/j.cels.2017.03.006. ISSN 2405-4712. PMID 28334573.
- Alberts B, Johnson A, Lewis J, Raff M, Roberts K, Walter P. Molecular Biology of the Cell (Fourth ed.).
- "COPE database".