Endogenous β-D-galactoside binding lectin during the expansion of the yolk sac in the developing chick embryo.

A lectin with an affinity for β-D-galactoside-containing saccharides is present in the developing yolk sac from the chick embryo at stages from 2 to 7 days of incubation. This activity is present in the area vitellina (less differentiated) and the area vasculosa (more differentiated). In both areas, lectin activity increases significantly during the spreading of the yolk sac up to 5 days of incubation.