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provides a convenient method for staging embryos between stages 6 and 14. Somites form with regularity every 90 minutes. Stage 10 embryos have 10 somites, and as a rule of thumb, the embryo gains 3 somites during each stage (i.e. Stage 11 embryos have 13 somites, Stage 12 embryos have 16, etc.).
58:, the embryos are easily accessible. However, the rate of development can be affected by a range of factors; including the specific breed, the temperature of incubation, the delay between laying and incubation, and the time of year, raising the need to create a standardised system based on
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There had been a previous attempt to create a morphological system for staging chick development by the German embryologists Keibel and
Abraham in 1900, but this system lacked detail and was not widely used, with most researchers relying on
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landmarks. Although most organ systems have a stereotypical appearance at each stage, there are a few which particularly lend themselves to use in staging chick development.
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number or age to identify the stage of development. Hamburger and
Hamilton aimed to provide a detailed description of developmental events, modeled on an earlier system for
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at stage 16, is a useful landmark for staging chick embryos until hatching. Between stages 15 and 35, the appearance of specific structures within the limbs (such as
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124:. The expansion of the anterior neural tube to form the brain may also be used to identify later stages.
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Hamburger, V; Hamilton, HL (1951). "A series of normal stages in the development of the chick embryo".
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as poultry makes them more readily available than other vertebrates (such as mice), and being
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is the only visible landmark, and its shape and size are used to stage HH1-6 embryos.
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in that it allows the developing chick to be accurately characterized during all
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However, beyond 22 somites (HH14) it is better to rely on other markers.
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and ending with a newly hatched chick. It is named for its creators,
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and digits); at later stages the length of the toes are used.
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The
Hamburger–Hamilton system provides advantages over the
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Chick embryos can be "staged" according to the different
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stages, and is used universally in chick embryology.
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is used in a similar way to stage later development.
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142:; which will give rise to the structures of the
27:(HH) are a series of 46 chronological stages in
31:development, starting from laying of the
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130:– the progressive segmentation of the
172:The formation and development of the
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50:for a number of reasons. Their
226:UNSW page on Chick Development
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42:Chicken embryos are a useful
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112:is formed by a process of
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39:and Howard L. Hamilton.
211:10.1002/jmor.1050880104
157:The morphology of the
198:Journal of Morphology
89:Stages of development
21:developmental biology
138:Formation of the
132:paraxial mesoderm
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140:branchial arches
103:primitive streak
46:in experimental
37:Viktor Hamburger
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241:Embryology
235:Categories
189:References
60:morphology
48:embryology
83:embryonic
56:oviparous
219:24539719
178:feathers
163:wing bud
246:Poultry
174:eyelids
148:pharynx
72:Axolotl
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167:joints
152:larynx
68:somite
23:, the
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29:chick
215:PMID
182:beak
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144:jaw
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