Homogenization of tissue in solution is often performed simultaneously with cell
lysis. To prevent lysis however, the tissue (or collection of cells, e.g. from
cell culture) can be kept at temperatures slightly above zero to prevent
autolysis, and in an
isotonic solution to prevent
osmotic damage. If freezing the tissue is possible,
cryohomogenization can be performed under "dry" conditions, and is often the method of choice whenever it is desirable to collect several distinct molecular classes (e.g. both
protein and
RNA) from a single sample, or combined set of samples, or when long-term storage of part of the sample is desired. Cryohomogenization can be carried out using a supercooled mortar and pestle (classic approach), or the tissue can be homogenized by crushing it into a fine powder inside a clean plastic bag resting against a supercooled solid metal block (more recently developed and more efficient technique). High-pressure homogenization is used to isolate the contents of
Gram-positive bacteria, since these cells are exceptionally resistant to lysis, and may be combined with high-temperature sterilization.
Dounce homogenization is a technique suitable for soft mammalian tissues, while lysis of mammalian cells has also been demonstrated via centrifugation. ==References==