Freeze fracture images of ciliated epithelial cells, Figures 8 (top) and 9 (bottom 2 panels) from Chapter 1 (The Cell Surface) of 'The Cell, 2nd Ed.' by Don W. Fawcett M.D. Figure 8 shows the P-face of ciliated epithelial cells from the ductus efferens of the rat, highlighting the "ciliary necklace" of imtramambrane particles the form several circumferential rows around the base of the shaft of each cilium. Figure 9 reveals linear arrays of particles that can be found on a small percentage of columnar epithelial cells in the colon and rectum of primates, shown here on the brush border of surface columnar cells from human rectal mucosa. A PDF copy of the accompanying chapter from Don Fawcett's The Cell is available on the ASCB's BioEDUCATE website.
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. The intramembranous particles represent integral membrane proteins.
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