A stylet for a biopsy needle is provided with a specimen recess inwardly of the distal end thereof which has a bottom wall parallel to the axis of the stylet and distal and proximal end walls which are reentrant relative to the distal end and proximal position of the stylet, respectively....http://www.google.co.uk/patents/US5394887?utm_source=gb-gplus-sharePatent US5394887 - Biopsy needle
