Clutch incubated and hatched  in the classroom.

EVENTS IN EMBRYONIC DEVELOPMENT

Before Egg Laying:

• Fertilization

• Division and growth of living cells

• Segregation of cells into groups of special function (tissues)

Between Laying and Incubation

• No growth; stage of inactive embryonic life

During Incubation:

• First day

  16 hours - first sign of resemblance to a chick embryo

  18 hours - appearance of alimentary tract

  20 hours - appearance of vertebral column

  21 hours - beginning of nervous system

  22 hours - beginning of head

  24 hours - beginning of eye

• Second day

  25 hours - beginning of heart

  35 hours - beginning of ear

  42 hours - heart beats

• Third day

  60 hours - beginning of nose

  62 hours - beginning of legs

  64 hours - beginning of wings

• Fourth day - beginning of tongue
• Fifth day - formation of reproductive organs and differentiation of sex
• Sixth day - beginning of beak
• Eighth day - beginning of feathers
• Tenth day - beginning of hardening of beak
• Thirteenth day - appearance of scales and claws
• Fourteenth day - embryo gets into position suitable for breaking shell
• Sixteenth day - scales, claws and beak becoming firm and horny
• Seventeenth day - beak turns toward air cell
• Nineteenth day - yolk sac begins to enter body cavity
• Twentieth day - yolk sac completely drawn into body cavity; embryo occupies practically all the space within the egg except the air cell
• Twenty-first day - hatching of chick

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