Freezing of neural tissues and their transplantation in the brain of rats: technical details and histological observations.

Embryonic neocortical and brainstem tissues were frozen, stored for variable periods, thawed and transplanted into the cerebellum of neonatal host rats. Various conditions related to freezing, media for freezing, DMSO as the cryoprotectant, and thawing were analyzed. The findings indicated that the following conditions yielded best results for neocortical transplantation: freezing at a rate of 1 degrees C/min, using rat amniotic fluid as the medium for freezing, using 10% DMSO as the cryoprotectant, storing the frozen tissues at -90 degrees C, thawing the tissues fast just prior to transplantation, and transplanting them in the host brain with little or no delay. Other conditions having adverse effects on the neural tissues were considered. Issues pertaining to transplantability and retainability of the neural tissues inside the host brain, and effects of freezing and thawing on the long-term viability of the neural tissues and their growth are discussed.