Erythroid cell differentiation in unincubated chick blastoderm in culture.

Morphologically distinct erythroid cell types characteristic of the primitive and the definitive erythroid cell lines, and embryonic and adult haemoglobins are produced when the unincubated chick blastoderm is cultured ventral side down on a filter raft to inhibit morphogenetic movements and subsequent primitive-streak formation mechanically in serum-free minimal essential medium. The primitive and definitive erythroid cell populations appear consecutively in culture even though there is no axis formation nor apparent morphogenesis. The information to produce both the early and late haemoglobins and erythroid cell types is independent of axis formation and of specific extra-embryonic influences, such as progressive induction exerted by the yolk mass.