Ultrastructural alterations in differentiating choroid plexus cells by puromycin

This study centres on the effect of puromycin, applied in various concentrations, on the differentiation of choroid plexus cells in tissue cultures. Puromycin added to these cultures in doses of 25, 50 and 100 μg/ml medium merely produced reversible cell changes when present for 2 h. After 3 h, choroid plexus cells react to continuous feeding with puromycin in a dose of 100μg/ml with an almost total loss of the membrane system of the endoplasmic reticulum. At this time many of the free ribosomes have disappeared. The results of this study suggest a continuous renewal of the membrane-structure of the endoplasmic reticulum.