A patient is admitted to the hospital for dehydration and malnutrition. on close observation of the intestine, it appears that the cells lining the intestine have fully formed microvilli. however, these microvilli are not uniformly standing upright and protruding into the lumen of the intestine, but are lying down so that full exposure to the contents of the intestine cannot be obtained. the doctors conclude that the patient may have a defect in what cellular component? microfibers actin myosin tubulin intermediate filaments