Preferred Label : primitive knot;
Uberon definition : 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].;
Uberon synonym : Hensen's node; embryonic organizer; embryo organizer; Spemann's organizer; organizer; embryonic shield; primitive node; shield; Hensen node; Spemann Mangold organizer;
Uberon related term : Henson's node; dorsal marginal zone; DMZ;
Uberon broad term : node;
Uberon Homology note : 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];
Origin ID : 0003062;
UMLS CUI : C1283999;
Automatic exact mappings (from CISMeF team)
- organ [Blood Transfusion thesaurus concept]
- organ [COVID-19 Thesaurus concept]
- organism [Blood Transfusion thesaurus concept]
Semantic type(s)
UMLS correspondences (same concept)
Uberon cross reference
contributes to morphology of
develops from
develops into
immediate transformation of
part of
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].