Effects of actinomycin D, amethopterin, and 5-fluro-2'-deoxyuridine on procentriole formation in Chinese hamster fibroblasts in culture

Synchronized Chinese hamster fibroblasts (Don-C) were cultured for 6 h in the presence of amethopterin, 5-fluorodeoxyuridine (FUdR), or actinomycin D and were then examined by electron microscopy of thin sections for the presence or absence of daughter procentrioles. Control cells were at mid S phase and contained obvious procentrioles in about 1 profile out of 140. Treatment with FUdR or amethopterin did not reduce this frequency significantly. However, serial section analysis did demonstrate a lack of procentrioles in some cells treated with amethopterin. Actinomycin was quite effective in preventing daughter procentriole formation.