Determination of Erythroid Cells in Unincubated Chick Blastoderm: stem cells/erythrocytes/unincubated chick blastoderm/critical mass).

Portions the size of 1/6 to 1/32 part of unincubated blastoderm cultured in an albumen-salineagar solid medium form erythroid cells under conditions which suppress normal co-ordinated movements for mesoderm induction. Anterior and posterior regions of unincubated blastoderm have the same potentiality to form erythroid cells. The marginal zone seems to be the contributor of prospective erythroid cells. Portion 1/16 part of unincubated blastoderm forms morphologically distinct erythroid cells of the primitive and definitive lines as in normal development in ovo. It seems progenitor cell(s) is pre-programmed to a particular pattern of differentiation and/or includes differentiation to various erythroid cell types as an obligatory step. This system provides novel experimental possibilities in the study of erythroid cell determination and differentiation.