Abstract: A method for isolating and enriching rare cells, including fetal nucleated erythrocytes from a peripheral blood sample is described. The method includes two centrifugation steps, the first a bulk separation step to enrich erythrocytes from other blood components. The second centrifugation comprises a colloidal density gradient medium dispersed in a hypertonic meltable gel. In one aspect of the invention, maternal erythrocytes may be hemolyzed prior to the second density gradient centrifugation to provide additional enrichment for fetal nucleated erythrocytes.

Abstract: A centrifuge tube and adaptor apparatus is provided which facilitates separation of biological materials and permits easy extraction of a fraction after centrifugation. The tube is a deformable tube with a wide upper chamber and a narrowed lower portion. The tube is supported within the centrifuge rotor or within another container within the centrifuge by a liquid support medium, which surrounds and supports the narrow portion of the tube, and thus prevents the tube from collapsing during high speed centrifugations.

Abstract: In an automatic focusing system an element (2) is inserted in the path of a beam of light (3) directed towards a sensor array. The element comprises a transparent material or predetermined reflective index, the element presenting a first region (4) of a first thickness and another region (5) of a greater thickness. The image falling on to the sensor comprises three areas--one area where the light has passed through the one region and another area where the light has passed through the further region and yet another area. The automatic focusing system derives signals from two of the areas and processes the signals so that the image is in focus in the third area.

Abstract: An apparatus and method for removing background noise and high frequency noise from an image by comparing each pixel in the image with neighboring pixels defining a variably shaped and sized kernel. The size and shape of the kernel are optimized for the particular characteristics of the data to be analyzed.