subpellicular microtubule

sub·pel·lic·u·lar mi·cro·tu·bule

a microtubule lying beneath the unit membrane (pellicle) of many protozoans, often as a palisade of longitudinally arranged fibrils connected by fine lateral bridges that support the external cell form; in certain sporozoan stages a fixed number of microtubules are found, extending longitudinally from the polar ring.