Particle displacement in epithelial cell membranes of rat prostate and pancreas induced by routine low temperature fixation.

When carried out at 4 degrees C in contrast to 37 degrees C, glutaraldehyde fixation for routine freeze-fracture specimen preparation results in displacement of membrane particles of epithelial cells of rat ventral prostate. Particle-free areas are observed in endoplasmic reticulum (ER), nuclear envelope, and Golgi membranes; particle aggregation is observed in lateral and basal portions of the plasma membrane. Multilamellar arrangement of lipids can be observed in some of the large particle-free areas. Thin section observation indicates that in the ER, particle-free areas coexist with segregation of cytoplasmic ground substance from the membrane surfaces. Particle-free patches are also observed in the ER membranes of pancreatic tissues fixed at 4 degrees C.