Fine needle aspiration and brush specimens. Simultaneous embedding in paraffin and enrichment.

Cell clusters and tissue fragments in fine needle aspiration and mucosal brush specimens can be studied as paraffin sections by processing sediments in frustoconical cups closed with a fine-meshed net. A 20-microns-mesh nylon net welded into a net piece prevents fragments from escaping from the cups but has hydraulic conductance large enough to ensure proper fluid exchange, provided that during processing the net is kept vertical (cup axis horizontal) and that the shape of the cup promotes fluid exchange. At embedding the cup is turned vertical, and the specimen, in the melted paraffin, becomes enriched by sedimentation at the bottom of the cup. When hardened, the paraffin cone is twisted off the cup by means of the net piece, and the specimen in the top layer of the cone is sectioned.