Stages are based on the external and/or internal morphological development of the vertebrate embryo, and are not directly dependent on either age or size.
Below is an alphabetical listing of different species and the systems used to stage embryonic development.
Hendrickx Embryology of the baboon. University of Chicago Press.
Cretekos CJ, Weatherbee SD, Chen CH, Badwaik NK, Niswander L, Behringer RR, Rasweiler JJ 4th. Embryonic staging system for the short-tailed fruit bat, Carollia perspicillata, a model organism for the mammalian order Chiroptera, based upon timed pregnancies in captive-bred animals. Dev Dyn. 2005 Jul;233(3):721-38.
Hamburger and Hamilton A series of normal stages in the development of the chick embryo. J. Morph. 88 p49 (1951)
Butler and Juurlink An atlas for staging mammalian and chick embryos. CRC Press Inc., Florida (1987)
Harman and Prickett The development of the external form of the guinea-pig between the ages of 11 and 20 days of gestation. Am. J. Anat. 49 p351 (1932)
Donkelaar Stages in the prenatal development of the chinese hamster. Anat. Embryol. 156 p1 (1979)
Carnegie 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.
As this staging can be applied to all vertebrates, and most vertebrate embryos develop during the embryonic period in much the same way, we can directly compare the timing of development for different species. Carnegie is the name of a historical US embryology institute.
O'Rahilly Early human development and the chief source of information on staged human embryos. Eur. J. Obstet. Gynec. Reprod. Biol. 9 p273 (1979)
Phillips The embryology of the common marmoset. Adv.
Hendrickx and Sawey Embryology of the rhesus monkey. The Rhesus Monkey, Bourne (ed), Academic Press, NY (1975)
Theiler The house mouse. Springer-Verlag, NY (1972)
Staging of gastrulating mouse embryos by morphological landmarks in the dissecting microscope. Downs KM, Davies T Development 1993 Aug;118(4):1255-66 PubMed Entry | DevelopmentArticle
Abstract: "We describe and illustrate a set of morphological landmarks for classifying mouse embryos by gross morphology from before gastrulation to the beginning of organogenesis. These landmarks are visible at the resolution of the dissecting microscope in embryos that are intact except for reflexion of Reichert's membrane. Adoption of these criteria should facilitate interpretation of both the expression patterns of genes and the consequences of experimental manipulation of embryos during early postimplantation development."
Marrable The embryonic pig. A chronological account. Pitman Medical, London (1971)
Witschi Growth. Altman and Dittmer (ed), Fed. Soc. Exp. Biol., Washington (1962)
Edwards The external development of the rabbit and rat embryo. Advances in teratology, Vol 3, Woollam (ed), Academic Press, NY (1968)
Bryden Embryology of the sheep. J. Morphology 138 p169 (1972)
The data in relation to days is only an approximation (an average of the range) due to the variability that occurs in normal developmental. The most common measurement is the crown to rump length (CRL) and the effects of fixation should always be considered when making these measurements.
From the table you can see that to reach the end of embryonic development, Carnegie stage 23, can take from as little as 10 days in chickens to nearly 60 days in humans.
Species |
Stage |
|
|
|
|
|
|
|
|
|
|
|
|
|
|
|
|
Days |
20 |
22 |
24 |
28 |
30 |
33 |
36 |
40 |
42 |
44 |
48 |
52 |
54 |
55 |
58 |
|
|
Baboon |
Days |
23 |
25 |
27 |
28 |
29 |
30 |
31 |
33 |
35 |
37 |
39 |
41 |
43 |
45 |
47 |
|
Rhesus Monkey |
Days |
21 |
22 |
25 |
28 |
29 |
30 |
32 |
34 |
36 |
37 |
38 |
40 |
42 |
44 |
46 |
|
Marmoset |
Days |
57 |
60 |
64 |
67 |
74 |
||||||||||
|
Days |
9 |
9.5 |
10 |
10.5 |
11 |
11.5 |
12 |
12.5 |
13 |
13.5 |
14 |
14.5 |
15 |
15.5 |
16 |
|
|
Rat |
Days |
10.5 |
11 |
11.5 |
12 |
12.5 |
13 |
13.5 |
14 |
14.5 |
15 |
15.5 |
16 |
16.5 |
17 |
17.5 |
|
Chinese Hamster |
Days |
10 |
10.5 |
11 |
11.5 |
12 |
12.5 |
13 |
13.5 |
14 |
14.5 |
15 |
15.5 |
16 |
16.5 |
17 |
|
Guinea Pig |
Days |
14.5 |
15 |
15.5 |
17 |
18 |
19 |
20 |
21 |
22 |
23 |
24 |
25 |
26 |
27 |
29 |
|
Rabbit |
Days |
8 |
8.5 |
9.5 |
10.5 |
11 |
12 |
12.5 |
13.5 |
14 |
14.5 |
15.5 |
16 |
16.5 |
17 |
18 |
|
Sheep |
Days |
15 |
16 |
17.5 |
18.5 |
19.5 |
20.5 |
22 |
23 |
24.5 |
25.5 |
27.5 |
29.5 |
30 |
33 |
|
|
Pig |
Days |
14 |
15 |
16 |
17 |
18 |
19 |
20.5 |
21.5 |
23 |
24 |
25.5 |
27.5 |
29 |
30.5 |
32.5 |
|
Days |
1 |
1.5 |
2 |
2.25 |
2.5 |
3 |
3.25 |
3.75 |
4.75 |
5.5 |
6.25 |
7.25 |
7.75 |
8.5 |
10 |
Source: Butler, H. and Juurlink, B.H.J. An atlas for staging mammalian and chick embryos. CRC Press Inc., Florida (1987) and specific references listed below.
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Our understanding of development relies a great deal on our ability to organise embryonic events into a timed sequence. This means that we can not only understand the order of events but also when they occur.
This is also experimentally useful as comparisons can be then made between embryos of the same species.
This page is a summary of a great deal of work by other embryologists over many years (see references) to stage embryos from different species, and having done so, we can also compare the timing of embryonic development between species.
Note that the day timing for each stage is the average of a range from many embryos, and I have also included a table of the data used to generate the comparison graph.
Please cite the original authors when using this data.
Please email Dr Mark Hill if you wish to make a comment about this current project.