Transmission electron micrograph of intercalated disks with a desmosome from the atria of mouse cardiac muscle cells. The intercalated disks are where the junction of two opposing membranes of adjacent cardiac muscle cells meet, which are held together by gap junctions and desmosomes. Intercalated disks function to aid in the rapid spread of action potential and in synchronizing muscle contractions. The gap junction allows small molecules and ions such as Calcium, Sodium and Potassium to move from one cell to another creating a direct electrical connection between the two adjacent cells. The desmosome specializes in spot like cell-cell adhesions which work to resist the forces of cardiac muscle expansion and contraction.
Primary fixation included: 2.5 % glutaraldehyde, 2% formaldehyde in 0.1 M Na-phosphate buffer, pH 7.4. Post-fixed in 2% OSO4 in 0.1 M Na-phosphate buffer, pH 7.4. Stained en bloc in 1% uranyl acetate. The tissue was then dehydrated in a graded series of ethanol and infiltrated with Spurr’s resin. Thin sections of 70 nm were trimmed using a diamond knife and post-stained in uranyl acetate and lead citrate. This micrograph image was taken using a Phillips CM 100 transmission electron microscope at an accelerating voltage of 80kV.
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