Histologic structures preserved for 21,300 years.

Histologic examination of rehydrated tissue samples from late Pleistocene (Alaskan) mammal mummies demonstrates that the preservative effect of freezing and drying extends to remains 15,000 to 25,000 years old. Some muscle and liver tissue retained identifiable histologic structures. Most tissues were completely disintegrated and partly replaced by masses of bacteria, an indication of considerable postmortem decay before the remains were entombed beneath the permafrost zone.