Abstract
Ontogenetic studies of erythrocyte antigens were carried out in three systems of the chicken. There were differences among the systems, and also among the antigens within one system, in the developmental stages at which they could first be detected. The antigens in the F and H systems were detected in early embryonic stages, but the antigens in the B system exhibited considerable variability in the time of appearance-that is, from late embryonic stages to several days after hatching.
The percentage of chicks in which it was possible to estimate genotypes for the B system decreased temporarily after hatching. The agglutinability of the red blood cells of chicks increased to the same titer as in adult by the 30th day after hatching.
