We use two different kinds of media. Most cells are grown in DMEM. A few lymphoid cell lines are grown in RPMI. Cells grown in DMEM must be grown in a 10% CO2 atmosphere. As a result, most of our incubators are set for this. In contrast, cells grown in RPMI must be grown in a 5% CO2 atmosphere. We have one incubator set up for this. If you grow cells in RPMI in 10% CO2, the medium will be too acidic (yellow).

DMEM.

This is an abbreviation for Dulbecco/Vogt modified Eagle's (Harry Eagle) minimal essential medium. We use commercially-made DMEM as the medium for most cells. DMEM differs from the original MEM in that it contains approximately 4 times as much of the vitamins and amino acids present in the original formula, and some (2 to 4 fold) more glucose. It also contains iron and a few other oddments. These modifications were made by Marguerite so she did not have to come in on Sunday to change the medium on her cells.

Most kinds of cells--human, monkey, hamster, rat, mouse, chicken--grow well in this medium.

RPMI.

This is an abbreviation for Roswell Park Memorial Institute medium. Human lymphoid cells are traditionally grown in RPMI medium. This is made from a mix by Margie. This medium contains a great deal of phosphate and is formulated for 5% CO2.

Medium is always supplemented with serum.

Most cell lines are grown in DMEM supplemented with either 10% calf serum or 10% fetal calf serum. Transformed cells usually grow well in calf serum. Normal 9non-transformed) cells sometimes require fetal calf serum, which is richer. Some clones of 3T3 cells do noticeably better in fetal calf serum. Some very fastidious cells are grown in 20% fetal calf serum.

Due to the cost and scarcity of fetal calf serum, some cells are grown in horse serum instead.

The medium of some lymphoid cells is supplemented with 5 x 10-5 M 2-mercaptoethanol. It does not matter whether this has undergone oxidation.

Some cells benefit from the inclusion of 2 mM glutamine, 2, 5 or 10% tryptose phosphate broth, 2 mM pyruvate, or non-essential amino acids in their media. For example, Mary-Ann Campbell always puts pyruvate and non-essential amino acids, in addition to mercaptoethanol, in the medium of her B cells.