Progressive somatofugal activation of cerebroside sulfotransferase in the developing chick optic fibers.

A myelination parameter of the chick optic pathway has been investigated: the activity of cerebroside sulfotransferase. Evidence is presented for a somatofugal progression of the enzyme activity peak along the optic nerve, chiasm, optic tract, tectum anterior, and tectum posterior. The enzyme activity appears on the fifteenth embryonic day and reaches a maximum in the nerve two days before hatching. One day after hatching, the peak is found in the chiasm, and three days after that in the optic tract. The peak is found in the tectum anterior on the tenth day. The results suggest a somatofugal progression of myelination.