Surface culture of fetal mammalian brain cells: Effect of subculture on morphology and choline acetyltransferase activity

Cells from brains of fetal rats were grown in surfece cell culture for up to 46 days and were subjected to two subculturing cycles with mild trypsin treatment. The cells maintained their characteristic morphology into third passage, and some putative neurons developed the ability to abhere directly to plastic surfaces. The specific activity of choline acetyl‐transferase reached higher levels in third than in first passage cultures. An increase of at least 34‐fold was obtained in the total activity of enzyme, the major increments occurring during first and third passages. The data suggest that choline acetyltransferase‐producing cells may be capable of multiplication in culture.