Abstract
In an electron microscopic study it was demonstrated that type C particles (L cell virions, LCV) were produced at a relatively high frequency in Earle's L cells (929 subline) when these cells had been incubated in the presence of 5-bromodeoxyuridine (BuDR) at a concentration of 10-4M. LCV appeared within the intracytoplasmic vesicles of L cells at times later than 20 hours after the initiation of BuDR treatment. LCV particles were produced from the limiting membrane of the vesicles by the budding process toward the inside of the vesicles. Each of them had an electron-dense, coiled core 128±31nm in outside diameter coated by a single unit membrane (envelope). Such knobs as noted by some previous authors were not recognized on their surface.
