Relative Lack of Myelin in Optic Tracts as Result of Underfeeding in the Young Albino Rat.

Abstract

Sections of optic tracts from underfed and litter-mate control albino rats were stained en masse for myelin by a modification of the method descr. by Ulett, Dow and Larsell (Jour. Comp. Neurol. 30 1. 1944). Myelin densities were then detd. electrophotometrically and the results subjected to statistical analysis. Quantitative limitation of food intake sufficient to account for an avg. difference in body wt. between underfed and control animals of 55% at the end of the expt., resulted in a relative lack of myelin in the optic tracts of the former. The myelin concn. in the exptl. rats averaged 20% less than that of litter-mates fed the same diet ad libitum. Since the rats used in these expts. were 17-20 days of age at the start of the expt. and 50-52 days old when sacrificed, and since myelination of the optic tracts is normally completed between 40 and 50 days, it was concluded that the relative lack of myelin in the underfed animals was due to partial or complete arrest of the process of myelination.