Carnegie stages

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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.

Stages

Days are approximate, and reflect the days since the last ovulation before pregnancy ("Postovulatory age").

Stage 1: 1 days

• fertilization
• polar bodies

Stage 2: 3 days

• cleavage
• morula
• compaction

Stage 3: 4 days

• blastocyst and blastocoele
• embryonic disk
• trophoblast and embryoblast

Stage 4: 5-6 days

• syncytiotrophoblast
• cytotrophoblast
• amniotic ectoderm

Stage 5 (a-c): 7-12 days

• implantation
• bilaminar germ disk
• primary yolk sac
• amniotic cavity

Stage 6: 13-15 days

• primitive streak
• primitive groove
• chorionic villi

Stage 7: 15-17 days

• gastrulation
• neural plate
• start of hematopoiesis
• notochord

Stage 8: 17-19 days

• primitive pit

Stage 9: 19-21 days

• neural groove
• neural folds
• septum transversum
• placode
• early heart

Stage 10: 21-23 days

• pharyngeal arches #1 and #2
• cardiac loop
• intermediate mesoderm

Stage 11: 23-26 days

• sinus venosus
• mesonephric duct

Stage 12: 26-30 days

• upper limb buds

Stage 13: 28-32 days

• septum primum
• foramen primum

Stage 14: 31-35 days

• ureteric bud

Stage 18: 44-48 days

• septum secundum

See also

• Mammalian embryogenesis

External links

• 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 and 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 | Germ layer (Ectoderm, Endoderm, Mesoderm, Chordamesoderm, Paraxial mesoderm, Intermediate mesoderm, Lateral plate mesoderm)
Histogenesis and Organogenesis
Circulatory system: Primitive atrium | Primitive ventricle | Bulbus cordis | Truncus arteriosus | Ostium primum | Foramen ovale | Ductus venosus | Ductus arteriosus | Aortic arches | Septum primum | Septum secundum | Cardinal veins Nervous system: Neural development/Neurulation | Neurula | Neural folds | Neural groove | Neural tube | Neural crest | Neuromere (Rhombomere) | Notochord | Optic vesicles | Optic stalk | Optic cup Digestive system: Foregut | Midgut | Hindgut | Proctodeum | Rathke's pouch | Septum transversum Urinary/Reproductive system: Urogenital folds | Urethral groove | Urogenital sinus | Kidney development (Pronephros | Mesonephros | Ureteric bud | Metanephric blastema) | Fetal genital development (Wolffian duct | Müllerian duct | Gubernaculum | Labioscrotal folds) Glands: Thyroglossal duct Uterine support: Placenta | Umbilical cord (Umbilical artery, Umbilical vein, Wharton's jelly) | Amniotic sac (Amnion, Chorion)