Abstract: A pump for pumping shear sensitive material comprising a housing having an internal displacement chamber and a displacement rod. The displacement rod is reciprocable within the displacement chamber and the displacement chamber having an aperture through which the displacement rod is reciprocated. The aperture being sealed with respect no the displacement chamber by the displacement rod and an annular seal surrounding the displacement rod. The displacement chamber having an inlet opposite the aperture and an outlet radially disposed to the longitudinal axis of the displacement rod and in close proximity to the annular seal.