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 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 from embryo to embryo.
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.
- 1 Stages
- 1.1 Stage 1: 1 days
- 1.2 Stage 2: 3 days
- 1.3 Stage 3: 4 days
- 1.4 Stage 4: 5-6 days
- 1.5 Stage 5 (a-c): 7-12 days
- 1.6 Stage 6: 13-15 days
- 1.7 Stage 7: 15-17 days
- 1.8 Stage 8: 17-19 days
- 1.9 Stage 9: 19-21 days
- 1.10 Stage 10: 21-23 days
- 1.11 Stage 11: 23-26 days
- 1.12 Stage 12: 26-30 days
- 1.13 Stage 13: 28-32 days
- 1.14 Stage 14: 31-35 days
- 1.15 Stage 15: 35-38 days
- 1.16 Stage 16: 36-42 days
- 1.17 Stage 17: 42-44 days
- 1.18 Stage 18: 44-48 days
- 1.19 Stage 19: 48-51 days
- 1.20 Stage 20: 51-53 days
- 1.21 Stage 21: 53-54 days
- 1.22 Stage 22: 54-58 days
- 1.23 Stage 23: 56-60 days
- 2 See also
- 3 External links
Stages
Days are approximate, and reflect the days since the last ovulation before pregnancy ("Postovulatory age").Stage 1: 1 days
Stage 2: 3 days
Stage 3: 4 days
Stage 4: 5-6 days
Stage 5 (a-c): 7-12 days
- implantation
- bilaminar germ disk
- primary yolk sac
- amniotic cavity
Stage 6: 13-15 days
Stage 7: 15-17 days
- gastrulation
- neural plate
- start of hematopoiesis
Stage 8: 17-19 days
- primitive pit
Stage 9: 19-21 days
Stage 10: 21-23 days
- pharyngeal arches #1 and #2
- cardiac loop
- intermediate mesoderm
Stage 11: 23-26 days
Stage 12: 26-30 days
- upper limb buds
Stage 13: 28-32 days
- septum primum
- foramen primum
Stage 14: 31-35 days
Stage 15: 35-38 days
Stage 16: 36-42 days
Stage 17: 42-44 days
Stage 18: 44-48 days
Stage 19: 48-51 days
Stage 20: 51-53 days
Stage 21: 53-54 days
Stage 22: 54-58 days
Stage 23: 56-60 days
See also
External links
- [Overview at embryology.ch]
- [Photos at unsw.edu.au]
- [Overview at umich.edu]
- [Details on stages at lsuhsc.edu]
- [History of development]
- [List of structures by week, at mrc.ac.uk]
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