Chicken stages: Difference between revisions

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Introduction

Hamburger & Hamilton Stage 11 (40-45 hr; 13 somites)

Viktor Hamburger (1900 – 2001)

Hamburger & Hamilton staged the chicken embryo in 1951.^[1] The original paper had approx 25 citations between 1955 - 59, while in the year 1991 alone there were over 300 citations. Series of Embryonic Chicken Growth. J. Morphology, 88 49 - 92 (1951). Atlas recently republished by J.R. Sanes in Developmental Dynamics 195 229-275 (1992). There was also an earlier Witschi staging though the Hamburger Hamilton Stages most commonly currently used.

Franz Keibel (1861 - 1929)

An even older 1900 staging^[2] in the Normentafeln zur Entwicklungsgeschichte der Wirbeltiere - Gallus domestics (Normal Plates of the Development of the Chicken Embryo by Franz Keibel and Karl Abraham. This was part of a series of embryo stagings in different species designed by Franz Keibel.

See also the 1910 description of chicken somitogenesis staging.^[3]

The table overview below describes feature of the chicken that can be seen at specific times (mean of a range) after fertilization, see Hamburger Hamilton Stages page for complete details and stage images. Some of the stages can be clicked to see sample embryo pictures on another page. There is also a stage comparison with the alternative universal Witschi staging.

**Avian Incubation Periods**
Bird	Days
Budgerigar	18
Chicken	21
Duck	28
Finch	14
Goose	28
Guinea fowl	28
Muscovy duck	35
Parrot	26
Pheasant	24
Pigeon	18
Quail	16
Swan	35
Turkey	28

Historic Chicken Embryology
1883 History of the Chick \| 1900 Chicken Embryo Development Plates \| 1904 X-Ray Effects \| 1910 Somites \| 1914 Primordial Germ Cells 1919 Lillie Textbook \| 1920 Chick Early Embryology \| 1933 Neural \| 1939 Sternum \| 1948 Limb \| Movie 1961 \| Historic Papers

Hamburger Hamilton Stages

Hamburger Hamilton Stages	Age	Identification of Stages	Links
Before Laying
Early cleavage	3.5 - 4.5 hr	Shell membrane of egg formed in isthmus of oviduct
During cleavage		Germ wall formed from marginal periblast
Late cleavage	4.5 - 24.0 hr	Shell of egg formed in uterus
After Laying
1		Preprimitive streak (embryonic shield)
2	6 - 7 hr	Initial primitive streak, 0.3-0.5 mm long	Gastrulation
3	12 - 13 hr	Intermediate primitive streak
4	18 - 19 hr	Definitive primitive streak, 1.88 mm long	Gastrulation
5	19 - 22 hr	Head process (notochord)
6	23 - 25 hr	Head fold
7	23 - 26 hr	1 somite; neural folds	Somitogenesis
7 to 8-	ca. 23 - 26 hr	1-3 somites; coelom
8	26 - 29 hr	4 somites; blood islands
9	29-33 hr	7 somites; primary optic vesicles
9+ to 10-	ca. 33 hr	8-9 somites; anterior amniotic fold
10	33-38 hr	10 somites; 3 primary brain vesicles
11	40 - 45 hr	13 somites; 5 neuromeres of hindbrain
12	45 - 49 hr	16 somites; telencephalon	Heart
13	48-52 hr	19 somites; atrioventricular canal
13+ to 14-	ca. 50 - 52 hr	20-21 somites; tail bud
14	50 - 53 hr	22 somites; trunk flexure; visceral arches I and II, clefts 1 and 2
14+ to 15-	ca. 50 - 54 hr	23 somites; premandibular head cavities
15	50 - 55 hr	24 - 27 somites; visceral arch III, cleft 3
16	51 - 56 hr	26 - 28 somites; wing bud; posterior amniotic fold; trigeminal ganglion (CN V) close lateral head ectoderm.	Heart
17	52 - 64 hr	29-32 somites; leg bud; epiphysis
18	3 da	30 - 36 somites extending beyond level of leg bud; allantois
19	3.0 - 3.5 da	37 - 40 somites extending into tail; maxillary process
20	3.0 - 3.5 da	40 - 43 somites; rotation completed; eye pigment
21	3.5 da	43-44 somites; visceral arch IV, cleft 4	Heart
22	3.5 - 4.0 da	Somites extend to tip of tail
23	4 da	Dorsal contour from hindbrain to tail is a curved line
24	4.5 da	Toe plate, eye primordium reaches optic cup stage.
25	4.5 - 5.0 da	Elbow and knee joints	Heart
26	5 da	1st 3 toes
27	5.0 - 5.5 da	Beak
28	5.5 - 6.0 da	3 digits, 4 toes
29	6.0 - 6.5 da	Rudiment of 5th toe
30	6.5 - 7.0 da	Feather germs; scleral papillae; egg tooth
31	7.0 - 7.5 da	Web between 1st and 2nd digits
32	7.5 da	Anterior tip of mandible has reached beak
33	7.5 - 8.0 da	Web on radial margin of wing and 1st digit
34	8 da	Nictitating membrane
35	8.5 - 9.0 da	Phalanges in toes
36	10 da	Length of 3rd toe from tip to middle of metatarsal joint = 5.4±0.3mm; length of beak from anterior angle of nostril to tip of bill = 2.5mm; primordium of comb; labial groove; uropygial gland
37	11 da	Length of 3rd toe = 7.4¬±0.3mm; length of beak = 3.0 mm
38	12 da	Length of 3rd toe = 8.4¬±0.3 mm; length of beak = 3.1 mm
39	13 da	Length of 3rd toe = 9.8¬±0.3 mm; length of beak = 3.5 mm
40	14 da	Length of beak = 4.0 mm; length of 3rd toe = 12.7¬±0.5 mm
41	15 da	Length of beak from anterior angle of nostril to tip of upper bill = 4.5 mm; length of 3rd toe = 14.9¬±0.8 mm
42	16 da	Length of beak = 4.8 mm; length of 3rd toe = 16.7¬±0.8 mm
43	17 da	Length of beak = 5.0 mm; length of 3rd toe = 18.6¬±0.8 mm
44	18 da	Length of beak = 5.7 mm; length of 3rd toe = 20.4¬±0.8 mm
45	19 - 20 da	Yolk sac half enclosed in body cavity; chorio-allantoic membrane contains less blood and is "sticky" in living embryo
46	20 - 21 da	Newly-hatched chick

Standard Stage Comparison

Witschi Stages

Standard Stages (Witschi)	Hamburger Hamilton Stages	Age	Identification of Stages
Before Laying
3,4	Early cleavage	3.5-4.5 hr2	Shell membrane of egg formed in isthmus of oviduct
5,6	During cleavage		Germ wall formed from marginal periblast
7	Late cleavage	4.5-24.0 hr2	Shell of egg formed in uterus
After Laying
8,9	1		Preprimitive streak (embryonic shield)
10	2	6-7 hr	Initial primitive streak, 0.3-0.5 mm long
11	3	12-13 hr	Intermediate primitive streak
12	4	18-19 hr	Definitive primitive streak, ¬±1.88 mm long
13a	5	19-22 hr	Head process (notochord)
13b	6	23-25 hr	Head fold
14a	7	23-26 hr	1 somite; neural folds
14b	7 to 8-	ca. 23-26 hr	1-3 somites; coelom
14c	8	26-29 hr	4 somites; blood islands
15a	9	29-33 hr	7 somites; primary optic vesicles
15b	9+ to 10-	ca. 33 hr	8-9 somites; anterior amniotic fold
15c	10	33-38 hr	10 somites; 3 primary brain vesicles
16a	11	40-45 hr	13 somites; 5 neuromeres of hindbrain
16b	12	45-49 hr	16 somites; telencephalon
16c	13	48-52 hr	19 somites; atrioventricular canal
17a	13+ to 14-	ca. 50-52 hr	20-21 somites; tail bud
17b	14	50-53 hr	22 somites; trunk flexure; visceral arches I and II, clefts 1 and 2
17c	14+ to 15-	ca. 50-54 hr	23 somites; premandibular head cavities
17d	15	50-55 hr	24-27 somites; visceral arch III, cleft 3
18	16	51-56 hr	26-28 somites; wing bud; posterior amniotic fold
19	17	52-64 hr	29-32 somites; leg bud; epiphysis
20	18	3 da	30-36 somites extending beyond level of leg bud; allantois
21	19	3.0-3.5 da	37- 40 somites extending into tail; maxillary process
22	20	3.0-3.5 da	40-43 somites; rotation completed; eye pigment
23	21	3.5 da	43-44 somites; visceral arch IV, cleft 4
24	22	3.5-4.0 da	Somites extend to tip of tail
25	23	4 da	Dorsal contour from hindbrain to tail is a curved line
26	24	4.5 da	Toe plate
27	25	4.5-5.0 da	Elbow and knee joints
28	26	5 da	1st 3 toes
29	27	5.0-5.5 da	Beak
30	28	5.5-6.0 da	3 digits, 4 toes
31	29	6.0-6.5 da	Rudiment of 5th toe
32	30	6.5-7.0 da	Feather germs; scleral papillae; egg tooth
33a	31	7.0-7.5 da	Web between 1st and 2nd digits
33b	32	7.5 da	Anterior tip of mandible has reached beak
34a	33	7.5-8.0 da	Web on radial margin of wing and 1st digit
34b	34	8 da	Nictitating membrane
34c	35	8.5-9.0 da	Phalanges in toes
34d	36	10 da	Length of 3rd toe from tip to middle of metatarsal joint = 5.4¬±0.3mm; length of beak from anterior angle of nostril to tip of bill = 2.5mm; primordium of comb; labial groove; uropygial gland
34e	37	11 da	Length of 3rd toe = 7.4¬±0.3mm; length of beak = 3.0 mm
34f	38	12 da	Length of 3rd toe = 8.4¬±0.3 mm; length of beak = 3.1 mm
35a	39	13 da	Length of 3rd toe = 9.8¬±0.3 mm; length of beak = 3.5 mm
35b	40	14 da	Length of beak = 4.0 mm; length of 3rd toe = 12.7¬±0.5 mm
35c	41	15 da	Length of beak from anterior angle of nostril to tip of upper bill = 4.5 mm; length of 3rd toe = 14.9¬±0.8 mm
35d	42	16 da	Length of beak = 4.8 mm; length of 3rd toe = 16.7¬±0.8 mm
35e	43	17 da	Length of beak = 5.0 mm; length of 3rd toe = 18.6¬±0.8 mm
35f	44	18 da	Length of beak = 5.7 mm; length of 3rd toe = 20.4¬±0.8 mm
36a	45	19-20 da	Yolk sac half enclosed in body cavity; chorio-allantoic membrane contains less blood and is "sticky" in living embryo
36b	46	20-21 da	Newly-hatched chick

Modified from: GROWTH Altman, P.L. and Dittmer, D.S. (ed) Biological Handbooks, FASEB (1962)

Images

HH4 and HH10 endoderm
HH20 head muscle MyoR
HH20 head muscle MyoR and MyoD

References

↑ Hamburger V & Hamilton HL. (1992). A series of normal stages in the development of the chick embryo. 1951. Dev. Dyn. , 195, 231-72. PMID: 1304821 DOI.
↑ Keibel F. and Abraham K. Normal Plates of the Development of the Chicken Embryo (Gallus domesticus). (1900) Vol. 2 in series by Keibel F. Normal plates of the development of vertebrates (Normentafeln zur Entwicklungsgeschichte der Wirbelthiere) Fisher, Jena., Germany.
↑ Williams LW. The somites of the chick. (1910) Amer. J Anat. 11(1): 56 -100.

Other Chicken Atlases

Vertebrate and Invertebrate Embryos (7th Edition) G.C. Schoenwolf, Prentice Hall, New Jersey
An Atlas of Embryology (1975) W.H. Freeman and B. Bracegirdle, Heinemann Educational Books, UK.
- This is an ATLAS (no description of development) , asically reprinted from the original 1963 edition.
- Photos with labelled diagrams covering Amphioxus (worm) Frog, Chicken.
Butler H. and Juurlink BHJ. An atlas for staging mammalian and chick embryos. (1987) CRC. Boca Raton, Florida.
- This ATLAS is not a complete series of development but has interesting comparisons of species. Mostly photos of embryos with a few drawn diagrams and a series of staging correlation graphs.

Glossary Links

Glossary: A | B | C | D | E | F | G | H | I | J | K | L | M | N | O | P | Q | R | S | T | U | V | W | X | Y | Z | Numbers | Symbols | Term Link

Cite this page: Hill, M.A. (2024, April 18) Embryology Chicken stages. Retrieved from https://embryology.med.unsw.edu.au/embryology/index.php/Chicken_stages

What Links Here?

[PMID1304821-1] Hamburger V & Hamilton HL. (1992). A series of normal stages in the development of the chick embryo. 1951. Dev. Dyn. , 195, 231-72. PMID: 1304821 DOI.

[Keibel1900-2] Keibel F. and Abraham K. Normal Plates of the Development of the Chicken Embryo (Gallus domesticus). (1900) Vol. 2 in series by Keibel F. Normal plates of the development of vertebrates (Normentafeln zur Entwicklungsgeschichte der Wirbelthiere) Fisher, Jena., Germany.

[Williams1910-3] Williams LW. The somites of the chick. (1910) Amer. J Anat. 11(1): 56 -100.

[1]

[2]

[3]

@@ Line 1: / Line 1: @@
+{{Header}}
 == Introduction ==
-[[File:Chick33h.jpg|thumb|Hamburger & Hamilton Stage 10 (33 hours)]]
+[[File:HHstage11.jpg|thumb|Hamburger & Hamilton Stage 11  (40-45 hr; 13 somites)]]
-Hamburger & Hamilton staged the chicken embryo in 1951.<ref><pubmed>1304821</pubmed></ref> The original paper had approx 25 citations between 1955 - 59, while in the year 1991 alone there were over 300 citations. '''Series of Embryonic Chicken Growth.''' J. Morphology, '''88''' 49 - 92 (1951). Atlas recently republished by J.R. Sanes in Developmental Dynamics '''195''' 229-275 (1993).
+{|
+| width=110px valign=top|[[File:Viktor Hamburger.jpg|100px|alt=Viktor Hamburger]]
-The table below describes feature of the chicken that can be seen at specific times (mean of a range) after fertilization. Some of the stages can be clicked to see sample embryo pictures on another page.
+Viktor Hamburger (1900 – 2001)
+| valign=top|[[Hamburger Hamilton Stages|Hamburger & Hamilton]] staged the chicken embryo in 1951.{{#pmid:1304821|PMID1304821}} The original paper had approx 25 citations between 1955 - 59, while in the year 1991 alone there were over 300 citations. '''Series of Embryonic Chicken Growth.''' J. Morphology, '''88''' 49 - 92 (1951). Atlas recently republished by J.R. Sanes in Developmental Dynamics '''195''' 229-275 (1992). There was also an earlier [[Chicken_Stages_-_Witschi|Witschi staging]] though the [[Hamburger Hamilton Stages]] most commonly currently used.
-There is also an comparisons with the alternative universal Witschi staging and, on another page, the staging of embryos.
+|-
+| [[File:Franz Keibel.jpg|100px|alt=Franz Keibel|link=Embryology History - Franz Keibel]]
+Franz Keibel (1861 - 1929)
+| valign=top|An even older 1900 staging<ref name=Keibel1900>{{Ref-Keibel1900}}</ref> in the Normentafeln zur Entwicklungsgeschichte der Wirbeltiere - ''Gallus domestics'' ([[Book_-_Normal_Plates_of_the_Development_of_Vertebrates_2|Normal Plates of the Development of the Chicken Embryo]] by [[Embryology_History_-_Franz_Keibel|Franz Keibel]] and Karl Abraham. This was part of a series of embryo stagings in different species designed by [[Embryology_History_-_Franz_Keibel|Franz Keibel]].
+See also the 1910 description of chicken somitogenesis staging.<ref name=Williams1910>{{Ref-Williams1910}}</ref>
+|}
+The table overview below describes feature of the chicken that can be seen at specific times (mean of a range) after fertilization, see [[Hamburger Hamilton Stages]] page for complete details and stage images. Some of the stages can be clicked to see sample embryo pictures on another page. There is also a [[Chicken_stages#Standard_Stage_Comparison|stage comparison]] with the alternative [[Chicken_Stages_-_Witschi|universal Witschi staging]].
+{{Bird incubation period table}}
-:{{Template:Chicken}}
+{{Chicken links}}
 == Hamburger Hamilton Stages ==
+[[Hamburger Hamilton Stages]]
 {| class="prettytable"
-| <center>'''Hamburger Hamilton Stages'''</center>
+|-bgcolor="CEDFF2"
-| <center>'''Age'''</center>
+| width="150px"|<center>'''Hamburger Hamilton Stages'''</center>
+| width="100px"|<center>'''Age'''</center>
 | <center>'''Identification of Stages'''</center>
+| <center>'''Links'''</center>
-|-
-| colspan="3" | <center>'''Before Laying'''</center>
 |-
+| colspan="4" | <center>'''Before Laying'''</center>
+|
+|-bgcolor="F5FAFF"
 | <center>Early cleavage</center>
-| 3.5-4.5 hr
+| 3.5 - 4.5 hr
 | Shell membrane of egg formed in isthmus of oviduct
@@ Line 28: / Line 45: @@
 |
 | Germ wall formed from marginal periblast
+|
-|-
+|-bgcolor="F5FAFF"
 | <center>Late cleavage</center>
-| 4.5-24.0 hr
+| 4.5 - 24.0 hr
 | Shell of egg formed in uterus
 |-
-| colspan="3" | <center>'''After Laying'''</center>
+| colspan="4" | <center>'''After Laying'''</center>
+|-bgcolor="F5FAFF"
-|-
 | <center>1</center>
 |
@@ Line 44: / Line 60: @@
 |-
 | <center>2</center>
-| 6-7 hr
+| 6 - 7 hr
 | Initial primitive streak, 0.3-0.5 mm long
+| [[Gastrulation]]
-|-
+|-bgcolor="F5FAFF"
 | <center>3</center>
-| 12-13 hr
+| 12 - 13 hr
 | Intermediate primitive streak
 |-
 | <center>4</center>
-| 18-19 hr
+| 18 - 19 hr
-| Definitive primitive streak, ¬±1.88 mm long
+| Definitive primitive streak, 1.88 mm long
+| [[Gastrulation]]
-|-
+|-bgcolor="F5FAFF"
 | <center>5</center>
-| 19-22 hr
+| 19 - 22 hr
 | Head process (notochord)
 |-
 | <center>6</center>
-| 23-25 hr
+| 23 - 25 hr
 | Head fold
+|
-|-
+|-bgcolor="F5FAFF"
 | <center>7</center>
-| 23-26 hr
+| 23 - 26 hr
 | 1 somite; neural folds
+| [[Somitogenesis]]
 |-
 | <center>7 to 8-</center>
-| ca. 23-26 hr
+| ca. 23 - 26 hr
 | 1-3 somites; coelom
+|
-|-
+|-bgcolor="F5FAFF"
 | <center>8</center>
-| 26-29 hr
+| 26 - 29 hr
 | 4 somites; blood islands
@@ Line 86: / Line 102: @@
 | 29-33 hr
 | 7 somites; primary optic vesicles
+|
-|-
+|-bgcolor="F5FAFF"
 | <center>9+ to 10-</center>
 | ca. 33 hr
@@ Line 96: / Line 112: @@
 | 33-38 hr
 | 10 somites; 3 primary brain vesicles
+|
-|-
+|-bgcolor="F5FAFF"
 | <center>11</center>
-| 40-45 hr
+| 40 - 45 hr
 | 13 somites; 5 neuromeres of hindbrain
 |-
 | <center>12</center>
-| 45-49 hr
+| 45 - 49 hr
 | 16 somites; telencephalon
+| [[:File:Heart chicken embryo stage 12.jpg|Heart]]
-|-
+|-bgcolor="F5FAFF"
 | <center>13</center>
 | 48-52 hr
@@ Line 114: / Line 131: @@
 |-
 | <center>13+ to 14-</center>
-| ca. 50-52 hr
+| ca. 50 - 52 hr
 | 20-21 somites; tail bud
+|
-|-
+|-bgcolor="F5FAFF"
 | <center>14</center>
-| 50-53 hr
+| 50 - 53 hr
 | 22 somites; trunk flexure; visceral arches I and II, clefts 1 and 2
 |-
 | <center>14+ to 15-</center>
-| ca. 50-54 hr
+| ca. 50 - 54 hr
 | 23 somites; premandibular head cavities
+|
-|-
+|-bgcolor="F5FAFF"
 | <center>15</center>
-| 50-55 hr
+| 50 - 55 hr
-| 24-27 somites; visceral arch III, cleft 3
+| 24 - 27 somites; visceral arch III, cleft 3
 |-
 | <center>16</center>
-| 51-56 hr
+| 51 - 56 hr
-| 26-28 somites; wing bud; posterior amniotic fold
+| 26 - 28 somites; wing bud; posterior amniotic fold; trigeminal ganglion (CN V) close lateral head ectoderm.
+| [[:File:Heart chicken embryo stage 16.jpg|Heart]]
-|-
+|-bgcolor="F5FAFF"
 | <center>17</center>
-| 52-64 hr
+| 52 - 64 hr
 | 29-32 somites; leg bud; epiphysis
@@ Line 145: / Line 163: @@
 | <center>18</center>
 | 3 da
-| 30-36 somites extending beyond level of leg bud; allantois
+| 30 - 36 somites extending beyond level of leg bud; allantois
+|
-|-
+|-bgcolor="F5FAFF"
 | <center>19</center>
-| 3.0-3.5 da
+| 3.0 - 3.5 da
-| 37- 40 somites extending into tail; maxillary process
+| 37 - 40 somites extending into tail; maxillary process
 |-
 | <center>20</center>
-| 3.0-3.5 da
+| 3.0 - 3.5 da
-| 40-43 somites; rotation completed; eye pigment
+| 40 - 43 somites; rotation completed; eye pigment
+|
-|-
+|-bgcolor="F5FAFF"
 | <center>21</center>
 | 3.5 da
 | 43-44 somites; visceral arch IV, cleft 4
+| [[:File:Heart chicken embryo stage 21.jpg|Heart]]
 |-
 | <center>22</center>
-| 3.5-4.0 da
+| 3.5 - 4.0 da
 | Somites extend to tip of tail
+|
-|-
+|-bgcolor="F5FAFF"
 | <center>23</center>
 | 4 da
@@ Line 175: / Line 194: @@
 | <center>24</center>
 | 4.5 da
-| Toe plate
+| Toe plate, eye primordium reaches optic cup stage.
+|
-|-
+|-bgcolor="F5FAFF"
 | <center>25</center>
-| 4.5-5.0 da
+| 4.5 - 5.0 da
 | Elbow and knee joints
+| [[:File:Heart chicken embryo stage 25.jpg|Heart]]
 |-
@@ Line 186: / Line 206: @@
 | 5 da
 | 1st 3 toes
+|
-|-
+|-bgcolor="F5FAFF"
 | <center>27</center>
-| 5.0-5.5 da
+| 5.0 - 5.5 da
 | Beak
 |-
 | <center>28</center>
-| 5.5-6.0 da
+| 5.5 - 6.0 da
 | 3 digits, 4 toes
+|
-|-
+|-bgcolor="F5FAFF"
 | <center>29</center>
-| 6.0-6.5 da
+| 6.0 - 6.5 da
 | Rudiment of 5th toe
 |-
 | <center>30</center>
-| 6.5-7.0 da
+| 6.5 - 7.0 da
 | Feather germs; scleral papillae; egg tooth
+|
-|-
+|-bgcolor="F5FAFF"
 | <center>31</center>
-| 7.0-7.5 da
+| 7.0 - 7.5 da
 | Web between 1st and 2nd digits
@@ Line 216: / Line 236: @@
 | 7.5 da
 | Anterior tip of mandible has reached beak
+|
-|-
+|-bgcolor="F5FAFF"
 | <center>33</center>
-| 7.5-8.0 da
+| 7.5 - 8.0 da
 | Web on radial margin of wing and 1st digit
@@ Line 226: / Line 246: @@
 | 8 da
 | Nictitating membrane
+|
-|-
+|-bgcolor="F5FAFF"
 | <center>35</center>
-| 8.5-9.0 da
+| 8.5 - 9.0 da
 | Phalanges in toes
@@ Line 235: / Line 255: @@
 | <center>36</center>
 | 10 da
-| Length of 3rd toe from tip to middle of metatarsal joint = 5.4¬±0.3mm; length of beak from anterior angle of nostril to tip of bill = 2.5mm; primordium of comb; labial groove; uropygial gland
+| Length of 3rd toe from tip to middle of metatarsal joint = 5.4±0.3mm; length of beak from anterior angle of nostril to tip of bill = 2.5mm; primordium of comb; labial groove; uropygial gland
+|
-|-
+|-bgcolor="F5FAFF"
 | <center>37</center>
 | 11 da
@@ Line 246: / Line 266: @@
 | 12 da
 | Length of 3rd toe = 8.4¬±0.3 mm; length of beak = 3.1 mm
+|
-|-
+|-bgcolor="F5FAFF"
 | <center>39</center>
 | 13 da
@@ Line 256: / Line 276: @@
 | 14 da
 | Length of beak = 4.0 mm; length of 3rd toe = 12.7¬±0.5 mm
+|
-|-
+|-bgcolor="F5FAFF"
 | <center>41</center>
 | 15 da
@@ Line 266: / Line 286: @@
 | 16 da
 | Length of beak = 4.8 mm; length of 3rd toe = 16.7¬±0.8 mm
+|
-|-
+|-bgcolor="F5FAFF"
 | <center>43</center>
 | 17 da
@@ Line 276: / Line 296: @@
 | 18 da
 | Length of beak = 5.7 mm; length of 3rd toe = 20.4¬±0.8 mm
+|
-|-
+|-bgcolor="F5FAFF"
 | <center>45</center>
-| 19-20 da
+| 19 - 20 da
 | Yolk sac half enclosed in body cavity; chorio-allantoic membrane contains less blood and is "sticky" in living embryo
 |-
 | <center>46</center>
-| 20-21 da
+| 20 - 21 da
 | Newly-hatched chick
 |}
 == Standard Stage Comparison ==
+[[Witschi Stages]]
 {| class="prettytable"
-| <center>'''Standard Stages(Witschi)'''</center>
+|-bgcolor="DDCEF2"
+| <center>'''Standard Stages (Witschi)'''</center>
 | '''Hamburger Hamilton Stages'''
 | <center>'''Age'''</center>
@@ Line 622: / Line 645: @@
 |}
 Modified from: '''GROWTH''' Altman, P.L. and Dittmer, D.S. (ed) Biological Handbooks, FASEB (1962)
+==Images==
+<gallery>
+File:Chicken_antero-posterior_endoderm_patterning_01.jpg|HH4 and HH10 endoderm
+File:Chicken HH20 MyoR expression 01.jpg|HH20 head muscle MyoR
+File:Chicken HH20 MyoR expression 02.jpg|HH20 head muscle MyoR and MyoD
+</gallery>
 ==References==
@@ Line 631: / Line 664: @@
 ** This is an ATLAS (no description of development) , asically reprinted from the original 1963 edition.
 ** Photos with labelled diagrams covering Amphioxus (worm) Frog, Chicken.
-* '''An Atlas for Staging Mammalian and Chick Embryos '''(1987) H. Bultler and B.H. Juurlink, CRC Press Inc., Florida
+* {{Ref-ButlerJuurlink1987}}
-** This ATLAS is not a complete series of development but has interesting comparisons of species.
+** This ATLAS is not a complete series of development but has interesting comparisons of species. Mostly photos of embryos with a few drawn diagrams and a series of staging correlation graphs.
-Mostly photos of embryos with a few drawn diagrams and a series of staging correlation graphs.
+{{Glossary}}
-{{Template:Glossary}}
-{{Template:Footer}}
+{{Footer}}
 [[Category:Animal Development]] [[Category:Chicken]]