Evidence that the earliest generated cells of the murine cerebral cortex form a transient population in the subplate and marginal zone.

We used bromodeoxyuridine to label the earliest generated cells of the murine cerebral cortex while they were dividing, and then observed their distributions at several instances later in development. Shortly before birth, many of the labelled cells were either above the cortical plate, in the marginal zone, or below it, in the region known as the subplate in other species. These cells had disappeared by postnatal day 21.