LOCATION OF NUCLEI OF DIFFERENT LABELING INTENSITIES IN AUTORADIOGRAPHS OF ANTERIOR FOREBRAIN OF POSTNATAL MICE INJECTED WITH [H-3]THYMIDINE ON 11TH AND 12TH DAYS POST-CONCEPTION

  • 1 January 1977
    • journal article
    • research article
    • Vol. 123  (APR) , 515-525
Abstract
The location of neuron nuclei of different labeling intensities in autoradiographs of the anterior forebrain of two 22 day old mice, injected with [3H]thymidine at 11 and 12 days post-conception, respectively, was charted on photocollages of sections enlarged 175 times. The pattern of distribution of the heavily labeled nuclei, i.e., those nuclei belonging to cells most likely to have been born shortly after the time of [3H]thymidine injection, indicated that the inner 2/3 of the neocortex was laid down along a ventro-dorsal gradient, i.e., the lateral neocortex started to form before the dorsal; cells born at a particular time lay in cortical layer VI at the dorsal edge of the gradient but became progressively more scattered through the cortex as the gradient was traced ventrally. Progressively more weakly labeled cells formed intermediate steps in this migration. A model of cortical growth fitting these findings was presented. Some inferences were also made about the possible role of the ganglionic eminences in providing cortical cells, at least during the initial stages of cortical histogenesis.