The development of a medium supplemented with egg extract for the maintenance of Drosophila cell lines

A saline extract was prepared from Drosophila eggs. When diluted to a concentration of 1% with Drosophila tissue culture medium, it did not support growth of cells from the Drosophila line D1 during the first few days of subculture as well as medium containing serum. When cells reached a stationary phase, however, the cell density in medium containing extract was greater than in medium containing serum. By altering the concentrations of the extract, and by adding bovine albumin, a medium was obtained in which D1 cells survived initial culturing, and which supported cell growth by day 4 as well as medium plus serum. The initial retardation of growth in medium containing egg extract might be due to the need of the cells to adapt to the new medium. At the present time four Drosophila cell lines have been maintained in this medium for more than 16 passages. Preliminary experiments with primary embryonic Drosophila cells indicate that medium containing 2% extract and bovine albumin retards the differentiation of these cells.