Here is a comparison between commercial fetal bovine serum and some special fetal bovine serum produced under conditions of maximal sterility, freedom from whole cells, and rapid processing in the cold. With the aid of a biology microscope, it has been found out that there is an improved cell growth-supporting capacity in the special fetal bovine sera than the commercial type. An approximate 10% of the commercial samples were contaminated with bacteria, fungi, or bovine viruses.

In the preparation of sera for nutritional studies, most unadapted cells, grown in culture, require serum as a component of the medium to maintain their proliferative capacity. While whole serum is permissible for routine purposes, studies involving nutritional parameters require that the constituents under study be removed before viewing under a biology microscope. The most commonly used procedure for removal of these constituents is dialysis of the whole serum. Most recently, passage of the serum over Sephadex columns has been employed.

Dialysis treatment of the serum consists of dialyzing the serum against 100 volumes of saline or Earle’s solution at 4 degrees centigrade with a change of solution every 2 hours for 48 hours. This process does not use a biology microscope just yet. Sufficient cellulose casing to contain the volume of serum is soaked in several changes of glass-distilled water to remove impurities and to make the tubing more pliable. A double knot is tied in one end, the serum poured in the tubing, and the end sealed with another double knot.