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This EM features the striated bands (sb) that link the
membranes under the surface depressions. The bands insert into the
epiplasm, and in this case, they separate to pass around the parasomal
sacs (ps) which lie to the right of a row of basal body/cilium
complexes. The bands have relatively electron transparent zones next
to the epiplasm that lie next to more opaque zones which are in turn
separated by a central medium electron transparent zone. This
differential banding suggests an overlap of filaments in the two more
opaque zones but there is no evidence of a muscle-like actomyosin
system. These bands probably provide tension and keep the cortical
ridges from flattening. If contractile they could account for the
cell’s ability to alter its shape when swimming through constricted
regions. For details on the striated bands in Paramecium see
Allen, J. Cell Biol. 49:1-20, 1971 and Allen, Aihara and Fok, J. Euk .
Microbiol. 45:202-209, 1998. gf, granulo-fibrillar material;
il, infraciliary lattice. EM taken on 12/18/68 by R. Allen with
Philips 300 TEM. Neg. 16,000X. Bar = 0.5µm.
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