Cell clusters and tissue fragments in fine needle aspiration and mucos
al brush specimens can be studied as paraffin sections by processing s
ediments in frustoconical cups closed with a fine-meshed net. A 20-mum
-mesh nylon net welded into a net piece prevents fragments from escapi
ng 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 spec
imen, in the melted paraffin, becomes enriched by sedimentation at the
bottom of the cup. When hardened, the paraffin cone is twisted off th
e cup by means of the net piece, and the specimen in the top layer of
the cone is sectioned.