what are contractile vacuoles in ciliates?
The contractile vacuole is a specialised type of vacuole; vacuoles are found in most cells but not all vacuoles are contractile vacuoles. The contractile vacuole, as its name suggests, expels water out of the cell by contracting.he contraction of the contractile vacuole and the expulsion of water out of the cell is called systole. Water always flows first from outside the cell into the cytoplasm, and is only then moved from the cytoplasm into the contractile vacuole for expulsion.