SYSTEMATIC WIDESPREAD CLONAL ORGANIZATION IN CEREBRAL-CORTEX

Cell lineage analysis in the cortex has revealed two clonal patterns, clustered and widespread clones. To determine the relationship of thes e patterns, progenitor cells were infected with a retroviral library e ncoding alkaline phosphatase, and cortical sibling cells were identifi ed using PCR. Clones labeled at E15 consisted of single cells or small cell clusters (52%) or of widespread cells (48%). However, widespread clones consisted of multiple neuronal or glial cell types, spaced sys tematically at 2-3 mm intervals. The data suggest that migratory multi potential progenitors divide asymmetrically at intervals defined by ce ll cycle length, producing single cells or clusters of cells in differ ent cortical regions. Transition from multipotentiality to more restri cted potential may correspond to changes in migratory behavior.