DIFFERENTIAL ENRICHMENT OF CELLS FROM EMBRYONIC RAT CEREBRA BY CENTRIFUGAL ELUTRIATION

—Centrifugal elutriation was used to obtain different populations of cells dissociated from 16‐day‐old rat embryo cerebra. The cell populations recovered were viable and could be maintained for several weeks in vitro. Sterile conditions were maintained throughout a preparation. Rat pups were removed by Caesarean section, the cerebra dissected and the cells dissociated by brief exposure to trypsin (0.125%, 6 min). An equivalent volume of elutriation medium (Dulbecco's medium containing 1% fetal calf serum, sodium bicarbonate, penicillin and streptomycin, EDTA, and deoxyribonuclease) was added to the trypsin‐cell suspension, the dissociated cells pelleted, resuspended in elutriation medium and counted. Up to 4 x 10⁸ cells were injected into the previously sterilized elutriator. Seven fractions were usually recovered from a preparation. The first fraction contained primarily red blood cells and cell debris, which could not be maintained in vitro. Upon culture, fraction 2 consisted of predominantly non‐neuronal cells, while fractions 3–6 contained neuronal and non‐neuronal cells. The morphological characteristics of the neurons differed in these fractions. Fraction 7 contained cells that had reaggregated during the elutriation procedure and exhibited a variety of cell types in vitro.