A method and apparatus for mucosal biopsy including a stationary base clevis component, upon which an open frame jaw is actuated rotationally to engage tissue and retract samples. A rack and pinion mechanism drives the jaw motion, which can be controlled axially by the physician. A metal retriever component captures tissue from the open frame jaw, and advances the samples proximally into the collection chamber, where they are maintained as the retriever is returned to its most distal position. Furthermore, the open frame design employs a reliable and compact means for actuation that can be decoupled from sample transfer and storage functions.