Chicken Embryo Development
This publication shows the development of a chicken embryo from Day 1 through Day 21.
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Hatching eggs.
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Infertile, unincubated egg. Blastodisc located on top of yolk appears irregular in shape.
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Fertile, unincubated egg. Blastoderm larger, more regular in shape and has a “donut-appearance.”
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Day 1 “Donut-shape” greatly enlarged and embryo lies within the donut ring.
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Day 2 Blood appears as “blood islets” in outer ring of developing embryo.
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Day 3 Circulatory system well developed. Formation of appendages.
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Day 4 Notice brain to body size relationship.
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Day 5 Brain continues to develop at rapid rate.
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Day 6 Wing development rapid. Development of egg tooth begins.
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Day 7 Egg tooth seen on tip of beak. Eyes very conspicuous.
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Day 8 Feather tracts seen on the back. Wings, feet, toes well developed.
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Day 9 Beginning formation of feathers.
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Day 10 Down feathers appear. Hardening of beak and egg tooth begins.
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Day 11 Eyelids have overgrown eyes.
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Day 12 Calcification of bone started. Toenails and down feathers on neck, thighs and wings present.
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Day 13 Appearance of scales on legs. Comb and wattles present.
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Day 14 Embryo acquires a more chick-like appearance.
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Day 15-19 Embryo grows rapidly assuming hatching position with the head under the right wing and beak toward the air cell. Remaining yolk sac begins entering body cavity.
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Day 20 Chick begins pipping through shell.
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Day 21 Chicks hatch and dry.
Kenneth S. Macklin, Extension Specialist, Professor; John P. Blake, former Extension Specialist; Joseph B. Hess, former Extension Specialist; Wallace D. Berry, Associate Professor; Robert A. Voitle, Professor Emeritus, all in Poultry Science at Auburn University; and Thomas A. Hess, Biological Sciences/Wildlife and Forestry, Auburn University
Reviewed June 2022, Chicken Embryo Development, ANR-1408