EMHPFFIG 3: Freeze artifacts in HPF/FS.
A. Nematode frozen by metal mirror fixation, where left side of the worm shows severe distortion due to poor freezing, while pharyngeal tissues on the right are better preserved. Scale bar, 2 µm.
B. High-power section through the hypodermis. Extreme distortion of most organelles (dark objects) was caused by extensive ice crystal formation. Cytoplasm is virtually white in color due to ice. Scale bar, 1 µm.
C. Higher power image showing starry-like dark fingers radiating outward from many objects. The dark fingers are distorted protein and lipid isolated by intervening fingers of (clear) ice crystals. Such defects are accentuated over a nucleus (right side of panel). Ice damage after HPF often looks like more subtle versions of the defects seen in B and C. Scale bar, 1 µm.
D. Low-power image showing nematode (above) embedded lengthwise in yeast paste (below), where individual yeast cells have failed to freeze or embed well, leaving either an empty hole or a shriveled wisp filling one side of the hole, thus weakening the plastic section. The worm also looks distorted. Similar clear holes may form at worm embryos inside the mother if resin infiltration fails. Scale bar, 2 µm.
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