Surprisingly, early dorso-medial and dorso-lateral progenitors of the chick pallium were able to sequentially produce cells expressing DL and UL markers in vitro (Suzuki et al., 2012). Caution should be made in the interpretation of these data, first because the authors did not verified the purity of the explanted regions and second because the expression of few marker is a very weak evidence that chick and neocortical progenitors generates the same cell types.