Freeze-etch replication of PNH erythrocytes for transmission electron microscopy

Freeze-etch replication of paroxysmal nocturnal hemoglobinurea [PNH] erythrocytes by a new freeze-fracture technique for transmission electron microscopy revealed two types of cells: 1. Macrocytes with round pits. 2. Microcytes with a single elongated spiculum and well defined wart-like spherical projections about 100 nm in diameter and intramembranous particles. A ridge separating the fracture face from the etched face should be achieved by proper etching to avoid ice crystallization