Development of the Mouse Anterior Commissure: III. Changes in Total Number of Neuroglia, Mitotic Cells and Dead Cells in the Anterior and Posterior Limbs with Age

The increase in glial numbers, cell density, mitotic index and necrotic index was compared and contrasted in both limbs of the anterior commissure of the developing mouse brain. At birth the anterior limb contained fewer cells than the posterior, but by 8 days the cell totals in both limb were similar, and thereafter there were always significantly more cells in the anterior limb. Glial proliferation appeared to cease earlier in the posterior limb. The mitotic indices were similar in both limbs declining steadily from birth except for a slight increase between 11 and 14 days in the anterior limb and at 14 days in the posterior. The necrotic index reached a maximum from 5 to 8 days in the posterior limb, and from 8 to 11 days in the anterior limb. A further small peak occurred in the posterior limb at 21 days, and in the anterior limb at 25 days. Except at birth glial density was always significantly higher in the posterior limb, and it is suggested that this may be due to the greater requirement for the removal of K+ ions from the less highly myelinated posterior limb.