An electrospinning apparatus and methodology is described that produces medical devices, such as scaffolds that induce the formation of a natural fibrous structure (primarily collagen and elastin) in a tissue-engineered medical device. The apparatus uses collection surfaces designed to manipulate or change the electrostatic field so that the electrospun fibers are arranged in desirable patterns that are similar to or mimic the fibrillar structure of an animal tissue. The manipulation results in fibers that are preferentially oriented in a predefined pattern. In addition, the interfiber space between the fibers and the fiber diameter are consistently within a predefined range. Using these techniques in conjunction with controlling polymer properties enables the production of a scaffold that has the structural and mechanical characteristics similar to the native tissue.