Where is the yolk sac absorbed into the chick's body cavity just before hatch, and where is the yolk stalk (Meckel's diverticulum) located?

On the 19th day of embryonic development, just 48 hours before hatch, the remaining yolk sac is physically drawn into the abdominal cavity of the chick via the umbilical opening, which then seals. This internalized yolk sac provides critical antibodies (maternal IgY) and nutrients for the chick's first 72 hours of life. The connection point between this yolk sac and the small intestine is the yolk stalk (vitelline duct). Post-hatch, as the yolk is fully absorbed, the yolk stalk regresses into a small, permanent lymphoid remnant known as Meckel's diverticulum, which is anatomically situated at the exact boundary where the jejunum ends and the ileum begins. If the umbilicus fails to close properly due to high incubation temperatures, bacteria (like E. coli) can enter, causing Omphalitis (yolk sac infection). Hatchery managers can research embryonic physiology in the Poultry Encyclopedia, buy digital thermometers and disinfectants on Poultry Plaza, track weekly chick prices on Poultry Rates, and source top-tier day-old chicks on Murghi Mandi.