Effect of 5-bromodeoxyuridine on the structure of differentiating choroid plexus cells in vitro

5-Bromodeoxyuridine caused structural alterations in a culture of choroid plexus cells of 13-day-old chick embryos, when added to the medium in a concentration of 0.122 mg/ml. The changes consisted of: increase of filamentous profiles, enlargement and segregation of the nucleoli, increase of vesicles in the cytoplasm, diminution of the tubules of the endoplasmic reticulum, and polymorphy of mitochondria. Under the same experimental conditions most of the connective tissue cells of 13-day-old chick embryos become necrotic.