Storage and long-term use of human biopsy tissue in histochemical studies.

Since a common problem in histochemical methods is the need for fresh-frozen tissue, techniques have been developed in this laboratory for the long-term storage and use of frozen tissue. Cryostat sections of tissue stored for as long as 4 years at -70 degrees C have been utilized to localize biogenic amines and acetylcholinesterase (AChE). The quality of the tissue and the histochemical demonstration of peripheral nerve fibers in the stored specimens is comparable to that seen in fresh-frozen tissue. Procedures are outlined for storing the tissue prior to cutting sections, for freezing and mounting the tissue for cutting, and for long-term storage of tissue blocks. These methods have been used successfully for organs of the mammalian urogenital system of several different mammals, including man, and for the brain, spinal cord, pituitary, adrenal, thyroid and submandibular glands of the rat. The methodology should be applicable to most organs and systems.