A medical device configured to collect tissue from within a subject's body includes an elongate shaft having a proximal end, a distal end, and a distal region proximate the distal end. A plurality of bristles may be positioned on the distal region to form a brush. The distal region may be configured to deform upon activation to increase a cross-sectional dimension of the brush. The cross-sectional dimension of the brush may be the largest dimension of the brush in a direction transverse to a longitudinal axis of the shaft.
