Primitive Streak

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primitive streak

[′prim·əd·iv ′strēk]
A dense, opaque band of ectoderm in the bilaminar blastoderm associated with the morphogenetic movements and proliferation of the mesoderm and notochord; indicates the first trace of the vertebrate embryo.

Primitive Streak


a longitudinal thickening of the outer layer of the embryonic disk, or blastodisk, in the embryos of birds, mammals, and humans; it is formed during the process of gastrulation. Mesodermal cells migrate from the primitive streak to the area between the ectoderm and endoderm. These cells later form the somites and lateral plates. In the anterior end of the primitive streak, the cell accumulation known as Hensen’s node develops. This cellular material becomes the notochord.

References in periodicals archive ?
Primitive Streak has since gone on to win two awards, has toured in seven countries since 1997 and has been seen by five million people.
Primitive Streak, a 12-year-old bay gelding, was one of her best horses.
Peter Weir, directing nominee for ``Master and Commander: The Far Side of the World,'' said filmmaking shouldn't be a competitive sport, although the movie awards process certainly elicits a primitive streak in everyone involved.
Margaret Farley (Yale University), however, points out that some Catholic theologians do not confer moral status on the embryo until after the primitive streak stage at about two weeks after fertilization, leaving the door open to use of the blastocyst for hESC research.
In the case of abortion, it may well be true that fetuses have embodied self-consciousness, but very few would agree that this is present by the end of conception and probably not even when the primitive streak first appears.
fashion collection called Primitive Streak, and body jewellery .
For there is a dark, primitive streak in the Scots psyche that hates women.
Turovets poster presentation titled "An in vitro Analog of the Primitive Streak to Derive High-Purity Definitive Endoderm Lineages Uncontaminated with Undifferentiated Cells" will be on Saturday, May 21, 2011.
Pbx proteins are pioneer TFs, which are specifically expressed in the primitive streak, the region of the embryo that will produce all mesoderm, and are critical for promoting mesodermal specification.