Use of Peldri II as a sublimation dehydrant in place of critical-point drying in fracture-label cytochemistry and in backscattered electron imaging fracture-label.

Peldri II, a fluorocarbon compound solid at room temperature, was used as a sublimation dehydrant in place of critical-point drying (CPD) in freeze-fracture cytochemistry. Its applicability to the fracture-label replica method was demonstrated using freeze-fractured rat pancreas labeled with Helix pomatia lectin-gold complex and phospholipase A2-gold complex for the detection of glycoconjugates and phospholipids, respectively. No difference in morphology and labeling pattern was detected in CPD-treated and Peldri II-treated tissue samples. The use of Peldri II was further extended to freeze-fractured rat duodenum labeled with wheat germ agglutinin-ovomucoid-gold complex. Again comparable results were obtained when duodenal samples were prepared according either to the conventional CPD method or to the Peldri II sublimation method. Freeze-fractured replicas of hamster ovaries labeled with Ricinus communis I-gold complex revealed that Peldri II could also be used as a sublimation dehydrant for preparing tissue samples for examination in the scanning electron microscope by the backscattered electron imaging mode.