Development of the Mouse Anterior Commissure: Part II: A Comparison of Glial Differentiation in the Anterior and Posterior Limbs of the Anterior Commissure of the Mouse Brain during Myelination using Semithin Light Microscopic Sections

The percentage of glioblasts, oligodendrocytes, astrocytes and microglia in the anterior and posterior limbs of the mouse anterior commissure during myelination was estimated from semithin, toluidine blue stained sections using the criteria of LING et al. (1973). From 11 to 25 days glial differentiation was more advanced in the anterior limb, but from 35 days the percentage of each type of glial cell was similar in each limb. The percentage of microglia was similar in each type of glial cell was similar in each limb. The percentage of microglia was similar in each limb and remained constant from 11 to 240 days. The percentage of astrocytes was similar in each limb at each age, but increased from 10% at 11 days to 20% at 35 days, when it became constant. The percentage of oligodendrocytes was higher in the anterior limb from 11 to 24 days, and continued to increase in both limbs up to 240 dyas. The precentage of dark oligodendrocytes increased with age, while the percentage of light and medium oligodendrocytes declined. Oligodendrocyte differentiation corresponded closely with myelination in each limb.