Sources
Help build the largest human-edited directory on the web.
Submit a site - Become an editor
Wikipedia. Licensed under the GNU Free Documentation License.
Are you an expert in this subject? Join the discussion and share your knowledge at Wikipedia.org.
Carnegie stages
From Wikipedia, the free encyclopedia
 |
Please help improve this article or section by expanding it. Further information might be found on the talk page or at requests for expansion. This article has been tagged since January 2007. |
In embryology, Carnegie stages are a standardized system of 23 stages used to provide a unified developmental chronology of the vertebrate embryo.
The stages are delineated through the development of structures, not by size or the number of days of development, and so the chronology can vary between species, and to a certain extent between embryos. It only covers the first 60 days of development; at that point the term embryo is usually replaced with the term fetus.
It was based on work by Streeter (1942) and O'Rahilly and Müller (1987). The name "Carnegie stages" comes from the Carnegie Institute.
While the Carnegie stages provide a universal system for staging and comparing the embryonic development of most vertebrates, other systems are occasionally used for the common model organisms in developmental biology, such as the Hamburger-Hamilton stages in the chick.
Days are approximate, and reflect the days since the last ovulation before pregnancy ("Postovulatory age").
- blastocyst and blastocoele
- embryonic disk
- trophoblast and embryoblast
- syncytiotrophoblast
- cytotrophoblast
- amniotic ectoderm
- implantation
- bilaminar germ disk
- primary yolk sac
- amniotic cavity
- gastrulation
- neural plate
- start of hematopoiesis
- notochord
- primitive pit
- pharyngeal arches #1 and #2
- cardiac loop
- intermediate mesoderm
- upper limb buds
- septum primum
- foramen primum
- Swiss embryology (from UL, UB, and UF) iperiodembry/carnegie02
- Embryology at UNSW wwwhuman/Stages/carnegie
- Photos at unsw.edu.au
- Overview at umich.edu
- Details on stages at lsuhsc.edu
- List of structures by week, at mrc.ac.uk
| Mammalian development of embryo and development of fetus (some dates are approximate - see Carnegie stages) |
|---|
| Week 1: Zygote - Morula - Blastula/Blastomere/Blastosphere - Archenteron/Primitive streak - Blastopore - Allantois - Trophoblast (Cytotrophoblast - Syncytiotrophoblast - Gestational sac)
Week 2: Yolk sac - Vitelline duct - Bilaminar disc Week 3: Hensen's node - Gastrula/Gastrulation - Trilaminar embryo Branchial arch (1st) - Branchial pouch - Meckel's cartilage - Somite/Somitomere - Sclerotome - Myotome - Germ layer (Ectoderm, Endoderm, Mesoderm, Chordamesoderm, Paraxial mesoderm, Intermediate mesoderm, Lateral plate mesoderm, Splanchnopleure, Somatopleure) Histogenesis and Organogenesis Uterine support: Placenta - Umbilical cord (Umbilical artery, Umbilical vein, Wharton's jelly) - Amniotic sac (Amnion, Chorion) |
 |
This developmental biology article is a stub. You can help Wikipedia by expanding it. |