Template:Hamburger Hamilton stages table

Hamburger Hamilton Stages	Age	Identification of Stages	Image
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
3	12-13 hr	Intermediate primitive streak
4	18-19 hr	Definitive primitive streak, ± 1.88 mm long
5	19-22 hr	Head process (notochord)
6	23-25 hr	Head fold
7	23-26 hr	1 somite; neural folds
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
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
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
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
25	4.5-5.0 da	Elbow and knee joints
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