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Contractile vacuoles cycle between a filling phase (diastole) and an
expelling phase (systole). This micrograph is of a CV whose contents
have been expelled recently and whose CV is said to be in systole. The
CV becomes essentially invisible at the light microscope-level because
the CV membrane undergoes tubulation while remaining bound to the 5 to
10 ribbons of microtubules that arise from the CV pore. This meshwork
of membrane tubules cannot be resolved as a distinct structure
separate from the background cytosolic contents. The space previously
occupied by the CV is now filled by smaller cytosolic components such
as ER and ribosomes and an occasional mitochondrion (m) and
lipid body. EM taken on 4/2/80 by R. Allen with Hitachi HU11A TEM.
Neg. 10,250X. Bar = 0.5µm. Part published in J. Protozool. 35:63-71,
1988.
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