| Abstract: | Tissue of the jejunal crypts of mouse intestine was fixed for 24-48 hr in acetic-ethanol, 1:3, and stained en bloc by the Feulgen reaction. The stained preparations were then stored 4 mo at -25 C in either 45% acetic acid alone or in dimethyl sulfoxide (DMSO) or glycerol to which 45% acetic acid had been added to make 15% of the total volume. Such storage preserved not only the stain but allowed autoradiographs to be made. No loss of silver grains or a decrease of labeling index was observed. The procedures are equally successful when used with double-labeling experiments. Solid, transplantable, experimental carcinomas can be preserved in a manner identical to that suggested for the epithelial cells of the crypts. |
