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primitive knot

^ http://purl.obolibrary.org/obo/UBERON_0003062

Organizer for gastrulation in vertebrates. The primitive knot starts as a regional knot of cells that forms on the blastodisc immediately anterior to where the outer layer of cells will begin to migrate inwards - an area known as the primitive streak. Posterior to the node is the primitive pit, where the cells of the epiblast (the upper layer of embryonic cells) initially begin to invaginate. This invagination expands posteriorly into the primitive groove as the cells layers continue to move into the space between the embryonic cells and the yolk. This differentiates the embryo into the germ layers - endoderm, mesoderm, and ectoderm. The primitive knot migrates posteriorly as gastrulation proceeds, eventually being absorbed into the tail bud.[WP]. the regional thickening of cells at the rostral tip of the vertebrate primitive streak through which gastrulating cells migrate anteriorally to form tissues in the future head and neck; this region organizes the formation of the three embryonic layers and establishes the longitudinal axis and the polarity of the embryo[MP]. [ http://en.wikipedia.org/wiki/Primitive_knot MP:0004066 http://en.wikipedia.org/wiki/Regional_specification#Dorsal.2Fventral_axis_.26_organizer ]

Synonyms: Hensen's node, primitive node, shield, embryonic shield, organizer, Spemann's organizer, embryonic organizer, embryo organizer, Hensen node, Spemann Mangold organizer

Term info

database cross reference
Subsets

uberon_slim, pheno_slim, early_development

UBPROP 0000001

A signaling center that directs the development of the whole embryo or of part of the embryo.[AAO], Embryonic structure that is a local accumulation of cells along the germ ring. The shield marks the dorsal side of the embryo[ZFIN:ZDB-PUB-961014-576].

UBPROP 0000003

The organizer is a central feature of vertebrate embryogenesis. It was first characterized in functional terms in amphibians by Spemann and Mangold (1924), and homologous tissues have since been identified in representatives of most other vertebrate classes, including mammals (the node), birds (Henson's node) and teleost fish (the embryonic shield).[well established][VHOG]

editor note

This class groups together possibly disparate structures, following homology class in vHOG; early development terms need review

has related synonym

DMZ, Henson's node, dorsal marginal zone, nodus primitivus

has alternative id

UBERON:0004018

id

UBERON:0003062

prefLabel

primitive knot