An apparatus for sampling tissue includes a tissue engaging member for engaging and retaining a sample of a tissue structure, and a cutter surrounding the tissue engaging member. The tissue engaging member and cutter are both operative to translate longitudinally with respect to one another, and a mechanism prevents the cutter from moving distally, the mechanism being released and the cutter freed to move distally when the tissue engaging member is in a predetermined position, preferably distal of the cutter. Thereby, out of sequence operation, e.g., premature cutting of the tissue before the tissue engaging member is in position, is prevented.