1. Chick Embryo Development
Dr. Douglas Rhoads
Professor Biological Sciences
Affiliated Faculty Center of Excellence for Poultry Science
Director of Graduate Program in Cell and Molecular Biology
University of Arkansas

2. The Egg

3. The Life of an Egg Male inseminates female
Female stores sperm for up to 2 weeks
Female has one ovary (left side)
Ovary has multiple follicles in hierarchy
One ovulation every 25 hours
timed to light cycle

4. Ovulation Primary Follicle ruptures Transiting the oviduct Oviposition
Sperm attach to germinal disk over egg
Acrosome reaction
One sperm penetrates egg membrane
Zygote begins development
Transiting the oviduct
Egg white albumen deposited
Egg membrane deposited
Shell added in Shell gland
Oviposition
about hours after ovulation
Embryo already at about 1000 cells

5. Embryo Growth Embryo on side of yolk
Floats up (hen rocks and reorients)
Incubation temperature of 39 to 40 C
Embryo divides into Embryo and Extra-embryonic tissue
Extra-embryonic tissue
Blood cell production
Blood islands >> Blood ring
Fuses with embryo circulatory system
Grows out around yolk
Heart pumps blood out around yolk and back to embryo
Absorbs yolk and albumen
Eventually, chick grows around and encompasses last of yolk through cloacal opening
Chick emerges from egg after 21 days

6. H&H chart

7. The First Three Days

8. Day 4 to 8

9. Embryo Dissection

10. Embryo Dissection

11. Embryo Dissection