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Freeze fracture of Vorticella microstoma (note different
species from preceeding). This cell had been placed in a relaxing
medium of saturated sodium pyrophosphate plus 0.01M EDTA (Stain Tech.
47:37, 1972) for 3 hours. A myoneme (my) enclosed by ER
membrane is fractured at the cell’s periphery. In this cell it appears
that the ER wraps around the myoneme. The P-fracture face of the
plasma membrane (Ppm) is studded with many IMPs of
significant size in contrast to the E-face of the outer alveolar
membrane (Eoam) which has few IMPs. Bits of the
P-face of the inner alveolar membrane (arrowheads) show many
IMPs on that face also. The P-face of the cytosolic-touching membrane
of the ER (Per) and the E-face of the
myonemal-touching membrane of the ER (Eer) are
visible. Linear arrays of IMPs on the E-face next to the myoneme may
be transmembrane proteins associated with the linkage complex
(lc). Mitochondria are the most prominent organelles in the
cytosol and their tubular cristae (arrows) sometimes show signs
of decoration with F1F0 ATP synthases. large
arrow, direction of shadowing of freeze fracture replica. EM taken
on 11/11/75 by R. Allen with JEM 100B TEM. Neg. 11,015X. Bar = 0.5µm.
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