Reconstruction of dissociated chick brain cells in rotation-mediated culture.

It is well known that the embryonic cells dissociated with the treatment of trypsin , when cultured on a gyratory shaker, tend to form a definite histoformative structure (Moscona 1961). The aggregation patterns, or the size, number, and shape of these cell aggregates, are characterized by the types and origins of the cells . These aggregates are formed through the cell-to-cell contacts which may be mediated by the materials with cell-binding activity, which showed an organ-specificity (Moscona 1962) . The production of such extracellularly functioning materials with specific cell-binding roles was inhibited by suppressing protein and RNA syntheses (Moscona and Moscona 1963). The aggregation patterns were affected by variations in culture conditions; the speed of rotation, the temperature, the kind and concentration of cells and so on (Moscona 1961) . In the neural-retina cells, it has been observed that the developmental stage at which cells were dissociated markedly affected aggregation; cells from progressively older embryos showed a decline in mutual adhesiveness (Moscona 1962). Kuroda (1963, 1964) has demon strated that in the cartilage cells dissociated from femora of 13-day chick embryos cultiva tion in monolayer reduced progressively the tendency of cells to aggregate, resulting in smaller and less compact clusters. In the present paper, it is shown that the aggregation patterns of the brain cells from chick embryos were affected by the concentration of serum in the culture medium, the age of the embryo from which the brain cells were dissociated, and the length of the days during which the cultures were maintained. And some possible relationships between such changes in aggregation patterns and the differentiation of the brain cells are discussed. It is also shown that sorting out of cells was observed when the cerebral cells and the neural-retina cells were intermingled.