Effect of fixation to the degradation of nuclear and mitochondrial DNA in different tissues.

Samples of different tissues were preserved in seven fixatives for periods of time extending from 1 to 336 days, to determine which fixatives reduce the time-dependent degradation of DNA and preserve the histological structure. To achieve these results, three PCR systems were used: FGA and TC11 (both for nuclear DNA) and HV1 for mitochondrial DNA (mt-DNA). For long-term storage in combination with amplification of nuclear and mt-DNA, consistent results were obtained in Carnoy's solution and glutaraldehyde. Variable results were observed for buffered formalin; an mt-DNA product could be detected even after 3 months of fixation. In regard to comparison of the different tissues, the quantities recovered from skeletal muscles and kidneys were higher than from other tissues.