Effect of Light Deprivation on the Postnatal Development of the Optic Nerve

Abstract

Gyllensten and Malmfors¹ examined inter alia the cross-sectional area and myelinated fibre distribution of the optic nerve in mice reared in the light or in the dark. In mice reared in complete darkness for 20 and 30 days, delay in myelination of the optic nerve fibres caused a reduction in the number of myelinated fibres of some 12 per cent. The number of larger fibres was affected to a greater extent than the number of smaller ones. At 20 days the cross-sectional area of the optic nerve was reduced by 3.4 per cent and at 30 days it was increased by 0.4 per cent; this was said to be insignificant. This latter finding prompts me to report some preliminary observations and a new experimental technique for light deprivation.