title: Vertebrate Embryonic Cleavage Pattern Determination.
abstract: The pattern of the earliest cell divisions in a vertebrate embryo lays the groundwork for later developmental events such as gastrulation, organogenesis, and overall body plan establishment. Understanding these early cleavage patterns and the mechanisms that create them is thus crucial for the study of vertebrate development. This chapter describes the early cleavage stages for species representing ray-finned fish, amphibians, birds, reptiles, mammals, and proto-vertebrate ascidians and summarizes current understanding of the mechanisms that govern these patterns. The nearly universal influence of cell shape on orientation and positioning of spindles and cleavage furrows and the mechanisms that mediate this influence are discussed. We discuss in particular models of aster and spindle centering and orientation in large embryonic blastomeres that rely on asymmetric internal pulling forces generated by the cleavage furrow for the previous cell cycle. Also explored are mechanisms that integrate cell division given the limited supply of cellular building blocks in the egg and several-fold changes of cell size during early development, as well as cytoskeletal specializations specific to early blastomeres including processes leading to blastomere cohesion. Finally, we discuss evolutionary conclusions beginning to emerge from the contemporary analysis of the phylogenetic distributions of cleavage patterns. In sum, this chapter seeks to summarize our current understanding of vertebrate early embryonic cleavage patterns and their control and evolution.
authors.affiliation: Laboratory of Genetics, University of Wisconsin-Madison, Genetics/Biotech Addition, Room 2424, 425-G Henry Mall, Madison, WI, 53706, USA.
authors.forename: Andrew
authors.initials: A
authors.lastname: Hasley
authors.affiliation: Division of Reproductive & Developmental Sciences, Oregon National Primate Research Center, Department of Physiology & Pharmacology, Oregon Heath & Science University, 505 NW 185th Avenue, Beaverton, OR, 97006, USA.|Division of Reproductive & Developmental Sciences, Oregon National Primate Research Center, Department of Obstetrics & Gynecology, Oregon Heath & Science University, 505 NW 185th Avenue, Beaverton, OR, 97006, USA.
authors.forename: Shawn
authors.initials: S
authors.lastname: Chavez
authors.affiliation: Department of Integrative Biosciences, L499, Oregon Health & Science University, 3181 SW Sam Jackson Park Road, Portland, OR, 97239, USA.
authors.forename: Michael
authors.initials: M
authors.lastname: Danilchik
authors.affiliation: Department of Molecular Biology & The Lewis-Sigler Institute for Integrative Genomics, Princeton University, Icahn Laboratory, Washington Road, Princeton, NJ, 08544, USA.
authors.forename: Martin
authors.initials: M
authors.lastname: Wühr
authors.affiliation: Laboratory of Genetics, University of Wisconsin-Madison, Genetics/Biotech Addition, Room 2424, 425-G Henry Mall, Madison, WI, 53706, USA. fjpelegri@wisc.edu.
authors.forename: Francisco
authors.initials: F
authors.lastname: Pelegri
mesh_terms: D000818:Animals; D005075:Biological Evolution; D002453:Cell Cycle / Q000235:genetics; D002455:Cell Division / Q000235:genetics*; D002970:Cleavage Stage, Ovum / Q000378:metabolism; D047108:Embryonic Development / Q000235:genetics*; D018507:Gene Expression Regulation, Developmental; D008322:Mammals; D008941:Spindle Apparatus / Q000235:genetics; D014714:Vertebrates / Q000196:embryology* / Q000235:genetics
keywords: Aster centering; Blastomere; Cell cleavage type; Cleavage plane determination; Compaction; Cytoskeleton; Evolution; Scaling; Spindle orientation