Primitive streak

For the album by The Subdudes, see Primitive Streak (album).
Primitive streak
Surface view of embryo of a rabbit.
arg. Embryonic disk.
pr. Primitive streak. gc. germinal crescent.
Details
Carnegie stage6b
Days15
Identifiers
Latinlinea primitiva
MeSHD054240
Anatomical terminology

The primitive streak is a structure that forms in the early embryo in amniotes.[1] In amphibians, the equivalent structure is the blastopore.[2] During early embryonic development, the embryonic disc becomes oval shaped, and then pear-shaped with the broad end towards the anterior, and the narrower region projected to the posterior. The primitive streak forms a longitudinal midline structure in the narrower posterior (caudal) region of the developing embryo on its dorsal side.[3] At first formation, the primitive streak extends for half the length of the embryo. In the human embryo, this appears by stage 6, about 17 days.[4]

The primitive streak establishes bilateral symmetry, determines the site of gastrulation, and initiates germ layer formation. To form the primitive streak, mesenchymal stem cells are arranged along the prospective midline, establishing the second embryonic axis, and the site where cells will ingress and migrate during the process of gastrulation and germ layer formation.[5]

The primitive streak extends through this midline and creates the left–right and cranial–caudal body axes.[6][7] Gastrulation involves the ingression of mesoderm progenitors and their migration to their ultimate position,[6][8] where they will differentiate into the mesoderm germ layer[5] that, together with endoderm and ectoderm germ layers, will give rise to all the tissues of the adult organism.

  1. ^ "Definition of AMNIOTE". www.merriam-webster.com. Retrieved 11 May 2022.
  2. ^ Wolpert, Lewis (2015). Principles of development (Fifth ed.). Oxford, United Kingdom. p. 113. ISBN 9780199678143.{{cite book}}: CS1 maint: location missing publisher (link)
  3. ^ Schoenwolf, Gary C. (2015). Larsen's human embryology (Fifth ed.). Philadelphia, PA. p. 57. ISBN 9781455706846.{{cite book}}: CS1 maint: location missing publisher (link)
  4. ^ Standring, Susan (2016). Gray's anatomy : the anatomical basis of clinical practice (Forty-first ed.). [Philadelphia]. p. 181. ISBN 9780702052309.{{cite book}}: CS1 maint: location missing publisher (link)
  5. ^ a b Mikawa T, Poh AM, Kelly KA, Ishii Y, Reese DE (2004). "Induction and patterning of the primitive streak, an organizing center of gastrulation in the amniote". Dev Dyn. 229 (3): 422–32. doi:10.1002/dvdy.10458. PMID 14991697. S2CID 758473.
  6. ^ a b Downs KM (2009). "The enigmatic primitive streak: prevailing notions and challenges concerning the body axis of mammals". BioEssays. 31 (8): 892–902. doi:10.1002/bies.200900038. PMC 2949267. PMID 19609969.
  7. ^ Chuai M, Zeng W, Yang X, Boychenko V, Glazier JA, Weijer CJ (2006). "Cell movement during chick primitive streak formation". Dev. Biol. 296 (1): 137–49. doi:10.1016/j.ydbio.2006.04.451. PMC 2556955. PMID 16725136.
  8. ^ Chuai M, Weijer CJ (2008). "The mechanisms underlying primitive streak formation in the chick embryo". Curr Top Dev Biol. Current Topics in Developmental Biology. 81: 135–56. doi:10.1016/S0070-2153(07)81004-0. ISBN 978-0-12-374253-7. PMID 18023726.