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