Biology:Cell type
A cell type is a classification used to identify cells that share morphological or phenotypical features.[1] A multicellular organism may contain cells of a number of widely differing and specialized cell types, such as muscle cells and skin cells, that differ both in appearance and function yet have identical genomic sequences. Cells may have the same genotype, but belong to different cell types 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,[2] dorsal root ganglion[3] and spinal cord.[4]
Animals have evolved a greater diversity of cell types in a multicellular body (100–150 different cell types), compared with 10–20 in plants, fungi, and protists.[5] The exact number of cell types is, however, undefined, and the Cell Ontology, as of 2021, lists over 2,300 different cell types.[6]
Multicellular organisms
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.
The simplest organism considered to have well defined cell types are some volvoceans, such as Volvox carteri, in which each organism is composed of distinct and interdependent cell populations, some somatic and some reproductive.[7]
Conceptual definition
Even though the concept of cell type is widely used, specialists still discuss the exact definition of what constitutes a cell type.[8]
Humans
A list of cell types in the human body may include several hundred distinct types depending on the source.[9][10]
A 2006 peer-reviewed article by Vickaryous and Hall listed 411 distinct human cell types.[11]
See also
- List of distinct cell types in the adult human body
- List of human cell types derived from the germ layers
- Stem cell
- Types of plant cells
References
- ↑ Zeng, Hongkui (2022). "What is a cell type and how to define it?". Cell 185 (15): 2739–2755. doi:10.1016/j.cell.2022.06.031. ISSN 0092-8674. PMID 35868277. PMC 9342916. https://doi.org/10.1016/j.cell.2022.06.031.
- ↑ "Brain structure. Cell types in the mouse cortex and hippocampus revealed by single-cell RNA-seq". Science 347 (6226): 1138–42. March 2015. doi:10.1126/science.aaa1934. PMID 25700174.
- ↑ "Unbiased classification of sensory neuron types by large-scale single-cell RNA sequencing" (in En). Nature Neuroscience 18 (1): 145–53. January 2015. doi:10.1038/nn.3881. PMID 25420068.
- ↑ "Neuronal atlas of the dorsal horn defines its architecture and links sensory input to transcriptional cell types" (in En). Nature Neuroscience 21 (6): 869–880. June 2018. 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.
- ↑ Osumi-Sutherland, David; Xu, Chuan; Keays, Maria; Kharchenko, Peter V.; Regev, Aviv; Lein, Ed; Teichmann, Sarah A. (2021-06-28). "Cell type ontologies of the Human Cell Atlas". Nature Cell Biology 23 (11): 1129–1135. doi:10.1038/s41556-021-00787-7. PMID 34750578.
- ↑ Gilbert, Scott F. (1997) (in en). Developmental biology (5th ed.). Sunderland (Mass.): Sinauer. pp. 17. ISBN 978-0-87893-244-3.
- ↑ "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, Bruce; Johnson, Alexander; Lewis, Julian; Morgan, David; Raff, Martin; Roberts, Keith; Walter, Peter. Molecular Biology of the Cell (Sixth ed.). p. 1217.
- ↑ "COPE database". http://www.cells-talk.com/routingold/.
- ↑ Vickaryous, Matthew K.; Hall, Brian K. (August 2006). "Human cell type diversity, evolution, development, and classification with special reference to cells derived from the neural crest" (in en). Biological Reviews 81 (3): 425–455. doi:10.1017/S1464793106007068. ISSN 1464-7931. PMID 16790079. http://doi.wiley.com/10.1017/S1464793106007068.
Further reading
- "The evolution of cell types in animals: emerging principles from molecular studies". Nature Reviews. Genetics 9 (11): 868–82. November 2008. doi:10.1038/nrg2416. PMID 18927580.
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