NEUROGENIC CELLS INHIBIT THE DIFFERENTIATION OF CARDIOGENIC CELLS

In this study, we present evidence that neurogenic cells inhibit the d ifferentiation of cardiogenic cells. When cells of the entire area pel lucida at stage 5 were dissociated and reaggregated, the aggregates di fferentiated into neural tissues and other structures of any germ laye r origin, except for heart tissues, despite the fact that the cardioge nic cells are already committed to differentiate. The phenomenon also occurs from stages 6 to 8, during which cells are in a higher state of commitment. Using combinations of different regions of the area pellu cida, it was confirmed that neurogenic cells are responsible for the i nhibition of cardiogenic cell differentiation. The inhibition is not s pecies-specific because quail and chick neurogenic cells inhibit each other's cardiogenic cell differentiation. Direct contact between cardi ogenic and neurogenic cells seems to be necessary for inhibition becau se cardiogenic cell differentiation takes place if cardiogenic and neu rogenic cells are separated by a porous membrane. Dissociated neural t ubes from early stages, but not dissociated telencephalon from 2-day-o ld chicks, also inhibit cardiogenic cell differentiation. These result s suggest that neurogenic cells may sequester molecules necessary for the differentiation of cardiogenic cells rather than produce inhibitor y molecules. (C) 1995 Academic Press, Inc.