UNSW Embryology

Carnegie Stages Movie

© Dr Mark Hill (2009)

Acknowledgements

Introduction

An animation of Carnegie stage 1 to 23 of Human embryonic development.

This current page also has the original animation of Carnegie stage 11 to 23 of Human embryonic development.

Movie of Human stages from 11-23.

Individual stages can be stepped through by using the righthand buttons at the bottom of the movie.

(Quicktime 96K)

More

Stages are based on the external and/or internal morphological development of the embryo, and are not directly dependent on either age or size. The human embryonic period proper is divided into 23 Carnegie stages. Criteria beyond morphological features include age in days, number of somites present, and embryonic length. (about Carnegie) Note that images are not to scale.

Related Stage pages: Carnegie Stage page with larger images of each stage. Week by week timeline of human development showing key features with links to other resources. Carnegie Stage Posters poster versions (in preparation) of the human carnegie stages.

Clicking on the small image will open a large image version of that stage.

To see the various staging systems for each species look at the Embryo Staging Systems references.

Carnegie Stage table

Stage	Days (approx)	Size (mm)	Images (not to scale, click image to see original)	Events
1	1 (week 1)	0.1-0.15		fertilized oocyte, pronuclei
2	2 - 3	0.1-0.2		cell division with reduction in cytoplasmic volume, formation of inner and outer cell mass
3	4 - 5	0.1-0.2		loss of zona pellucida, free blastocyst
4	5 - 6	0.1-0.2		attaching blastocyst
5	7 - 12 (week 2)	0.1-0.2		implantation
6	13 - 15	0.2		extraembryonic mesoderm, primitive streak
7	15 - 17 (week 3)	0.4		gastrulation, notochordal process
8	17 - 19	1.0 - 1.5		primitive pit, notochordal canal
9	19 - 21	1.5 - 2.5		Somite Number 1 - 3 neural folds, cardiac primordium, head fold
10	22 - 23 (week 4)	2 - 3.5		Somite Number 4 - 12 neural fold fuses
11	23 - 26	2.5 - 4.5		Somite Number 13 - 20 rostral neuropore closes
12	26 - 30	3 - 5		Somite Number 21 - 29 caudal neuropore closes
13	28 - 32 (week 5)	4 - 6		Somite Number 30 leg buds, lens placode, pharyngeal arches
Stage 13/14 shown in serial embryo sections series of Embryology Program
14	31 - 35	5 - 7		lens pit, optic cup
15	35 - 38	7 - 9		lens vesicle, nasal pit, hand plate
16	37 - 42 (week 6)	8 - 11		nasal pits moved ventrally, auricular hillocks, foot plate
17	42 - 44	11 - 14		finger rays
18	44 - 48 (week 7)	13 - 17		ossification commences
19	48 - 51	16 - 18		straightening of trunk
20	51 - 53 (week 8)	18 - 22		upper limbs longer and bent at elbow
21	53 - 54	22 - 24		hands and feet turned inward
Stage 22 shown in serial embryo sections series of Embryology Program
22	54 - 56	23 - 28		eyelids, external ears
23	56 - 60	27 - 31		rounded head, body and limbs
Following this stage Fetal Development occurs until birth (approx 40 weeks)

(Source: Rothenburger and Gay, 1995. and others)

References

Search Pubmed Now: Human[TITL]+embryo[WORD]+stages[WORD]

• Nishimura H, et al.   [See Related Articles] Normal development of early human embryos: observation of 90 specimens at Carnegie stages 7 to 13. Teratology. 1974 Aug;10(1):1-5.
• O'Rahilly R.   [See Related Articles] Early human development and the chief sources of information on staged human embryos. Eur J Obstet Gynecol Reprod Biol. 1979 Aug;9(4):273-80
• O'Rahilly R.   [See Related Articles] Guide to the staging of human embryos. Anat Anz. 1972;130(5):556-9.
• Gaubert-Cristol R, et al.   [See Related Articles] [End of embryonic somite period in the rat and a comparison with the corresponding embryonic period in humans]. Bull Assoc Anat (Nancy). 1991 Sep;75(230):55-9. French.

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