Apparatus for embedding biological specimens in paraffin or the like

Abstract

An apparatus for automatically pretreating and paraffining biological specimens in a single vessel for the preparation of specimen blocks to be microtomed into thin slices for microscopical study. A rotary selector valve assembly with a built-in gate valve placed a plurality of reagent vessels, containing various reagents including molten paraffin, in and out of communication with the processing vessel in a prescribed sequence. An air pump coacts with directional control valves to evacuate the processing vessel for drawing the successive reagents into same via the rotary selector valve assembly and to deliver gas under pressure into the vessel for the discharge of the reagents therefrom back into the respective reagent vessels. For automating the apparatus a level sensor is provided to the processing vessel in order to close the gate valve and to set the pump out of operation whenever a reagent is drawn into the processing vessel to a predetermined level. Also included are a first pressure switch for opening the gate valve in response to the delivery of the pressurized gas from the pump into the processing vessel, and a second pressure switch for stopping the pump and causing the selector valve assembly to communicate the processing vessel with the next reagent vessel in response to a pressure drop upon complete discharge of the reagent from the processing vessel.