The Spencer rotary microtome, often recognized as a, if not the, classic

Senior rotary microtome type

, is a precision instrument designed for cutting thin, consistent tissue sections (often 2–10

μmu

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m or more) for histopathology. It utilizes a handwheel-driven mechanism that moves a specimen block vertically against a stationary, often high-quality steel knife. 

Key features and details include: 

• Mechanism: A rotary, handwheel-driven action that allows for efficient, rapid, and serial sectioning.
• Applications: Widely used in laboratories for preparing tissue samples for light microscopy.
• Components: Typically features an adjustable knife holder, a specimen clamp (object holder), and a micron adjustment mechanism.
• Types: While the classic Spencer design is a manual, "senior" rotary type, variations exist for different cutting needs, such as sliding mechanisms.
• Usage: The operator turns a handwheel, which drives the block, while the blade remains stationary, producing high-quality paraffin sections.