Abstract: Apparatus for measuring the volume of the buffy coat and constituent cell sub-layers in blood. The apparatus includes a capillary tube with an insert disposed in the tube bore. The insert is formed of a material having a specific gravity which will enable it to float on the red cell layer of a centrifuged blood sample. The insert is an elongated body having a circular side wall, such as a cylinder, with a tapered upper end. The insert forms an annular free space with the tube bore into which the white cell layer settles. A small, axial channel is formed in or on the body to allow ready passage of the fluid constituent of the blood sample during centrifugation so as to minimize disruption of the cell layer interfaces which may otherwise occur during centrifugation of the blood sample.

Abstract: A technique for generally determining the buffy layer volume, white cell and platelet count or general reticulocyte count in a centrifugally separated mixture of a blood sample. A capillary centrifuge tube is used to hold the material mixture and an appropriately shaped body is disposed in the tube in the zone occupied by the constituent material whose volume is to be measured. The body reduces the available volume within the tube which may be occupied by the constituent material, and thus expands the axial extent of the constituent material to make visual measurement of the constituent material more accurate.

Abstract: A technique for generally determining the approximate volume of the white cell and platelet layers in a centrifugally separated mixture of anticoagulated blood. A centrifuge tube is used to hold the blood sample and an appropriately shaped body is disposed in the tube in the zone occupied by the white cell and platelet layers whose volume is to be measured. The body reduces the available volume within the tube which may be occupied by the white cell and platelet layers and thus expands the axial extent thereof to make visual measurement of the white cell and platelet layers more accurate. The body has an inwardly and upwardly tapered upper end portion which prevents platelet cells from aggregating on the top of the body.

Abstract: A technique for generally determining the volume of a layer of a constituent material in a centrifugally separated mixture of material. A centrifuge tube is used to hold the material mixture and an appropriately shaped body is disposed in the tube in the zone occupied by the constituent material whose volume is to be measured. The body reduces the available volume within the tube which may be occupied by the constituent material, and thus expands the axial extent of the constituent material to make visual measurement of the constituent material more accurate.