RESUMO
The vertical distribution of neurons of different birth dates in the mouse isocortex was measured and compared with the theoretical distributions of neurons accumulation in chronologically ordered columns. The agreement between observed and predicted results was close, so that, in spite of considerable scatter and overlap in the observed distribution of successive generations, the hypothesis that the isocortex is formed of columns of cells arranged from deep to superficial in chronological order of birth is still tenable. A computer model of a differentiation wave traveling across a proliferative system generating chronologically ordered columns was constructed and used to simulate the results of tritiated thymidine labelling experiments. Predicted and observed distributions were again close. The approach has been of value in pointing the way for future qualitative and quantitative studies.
