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This electron micrograph shows the E-fracture face (above) and P-fracture face (below) of the membrane of adjacent epithelial cells from the ciliary epithelium of the monkey eye. Intramembranous particles, representing integral membrane proteins, appear as bumpy projections, and are prominent in this image with high density on the p-face, but also can be detected on the e-face. This image, contributed by Giuseppina Raviola, is Figure 4 from Chapter 1 (The Cell Surface) of 'The Cell, 2nd Ed.' by Don W. Fawcett M.D. A PDF copy of the accompanying chapter is available on the ASCB's BioEDUCATE website.

Technical Details

With the freeze-fracture technique, tissue is rapidly frozen and cracked to shear along zones of weakness. Cleavage of membranes occurs along the hydrophobic interior of the lipid bilayer to reveal views of a "p-face" (the outwardly-facing inner half of the membrane) and an "e-face" (the inwardly-facing outer half of the membrane), and a metallic replica is made of the fractured surface.

Biological Sources

NCBI Organism Classification
unidentified monkey
Cell Type
epithelial cell
Cellular Component
plasma membrane
intrinsic to plasma membrane

Biological Context

Biological Process
plasma membrane organization


Giuseppina Raviola
ISBN 0721635849
The Cell, 2nd Ed. by D.W. Fawcett


This image is part of a group.
Data Qualifiers
processed data

Sample Preparation

Relation To Intact Cell
isolated subcellular component


Spatial Axis Image Size Pixel Size
X 898px ——
Y 1295px ——
*CIL – Cell Image Library accession number. Please use this to reference an image.