Fully automated preparation of high-quality stained blood films

A detailed description is given of the operation of Technicon's AutoSlide, which automatically produces a microscope-ready, precipitate-free, stained blood smear with superior cell distribution and good morphology. A 40-test-tube turntable carrying anticoagulated blood inputs samples at 40-second intervals. The blood films are drawn consecutively on a continuous Mylar substrate, with nylon mesh replacing the usual glass slide spreaders. This flexible substrate then passes through drying, fixing, staining and final drying stations. The methanol of conventional Romanowsky stains is replaced by low-volatility solvents. The fixing solution contains solvents, toluidine blue O, glutaraldehyde and a trace of water. The modified Giemsa-stain stock, when mixed with buffer, remains precipitate free for several days. Finally the blood film is imprinted with a date and identification number. Liquid monomer is dispensed onto each stained blood film, followed by a microscope slide. The monomer is then polymerized using ultraviolet light. Permanent transfer of the stained and labeled blood film occurs when the Mylar is stripped from the slide. The usable area for examination is approximately five times larger than that of a typical manual wedge smear.