title: The organelle of differentiation in embryos: the cell state splitter.
abstract: The cell state splitter is a membraneless organelle at the apical end of each epithelial cell in a developing embryo. It consists of a microfilament ring and an intermediate filament ring subtending a microtubule mat. The microtubules and microfilament ring are in mechanical opposition as in a tensegrity structure. The cell state splitter is bistable, perturbations causing it to contract or expand radially. The intermediate filament ring provides metastability against small perturbations. Once this snap-through organelle is triggered, it initiates signal transduction to the nucleus, which changes gene expression in one of two readied manners, causing its cell to undergo a step of determination and subsequent differentiation. The cell state splitter also triggers the cell state splitters of adjacent cells to respond, resulting in a differentiation wave. Embryogenesis may be represented then as a bifurcating differentiation tree, each edge representing one cell type. In combination with the differentiation waves they propagate, cell state splitters explain the spatiotemporal course of differentiation in the developing embryo. This review is excerpted from and elaborates on "Embryogenesis Explained" (World Scientific Publishing, Singapore, 2016).
authors.affiliation: Retired, University of Manitoba, Winnipeg, Canada.
authors.forename: Natalie K
authors.initials: NK
authors.lastname: Gordon
authors.affiliation: Retired, University of Manitoba, Winnipeg, Canada. DickGordonCan@gmail.com.|Embryogenesis Center, Gulf Specimen Aquarium & Marine Laboratory, 222 Clark Drive, Panacea, FL, 32346, USA. DickGordonCan@gmail.com.|C.S. Mott Center for Human Growth & Development, Department of Obstetrics & Gynecology, Wayne State University, 275 E. Hancock, Detroit, MI, 48201, USA. DickGordonCan@gmail.com.
authors.forename: Richard
authors.identifier: http://orcid.org/0000-0003-4970-9953
authors.initials: R
authors.lastname: Gordon
mesh_terms: D000199:Actins / Q000378:metabolism; D000465:Algorithms; D000558:Ambystoma mexicanum; D000663:Amphibians; D000818:Animals; D002454:Cell Differentiation; D003599:Cytoskeleton / Q000378:metabolism; D015509:Developmental Biology; D047108:Embryonic Development; D004847:Epithelial Cells / Q000502:physiology*; D053263:Gene Regulatory Networks; D006801:Humans; D008870:Microtubules / Q000502:physiology*; D008954:Models, Biological; D015388:Organelles; D020543:Proteome; D015398:Signal Transduction
chemical_list: D000199:Actins; D020543:Proteome
keywords: Cell organelle; Cell state splitter; Cytoskeleton; Differentiation; Embryo