microtomo

A microtome is an instrument used to cut extremely thin slices of material for microscopic examination. In histology and pathology, microtomes prepare thin sections of tissue that are embedded in a solid medium, typically paraffin wax, or cut from frozen samples for rapid analysis. Common forms include rotary microtomes, sliding microtomes, and cryomicrotomes; ultramicrotomes are used to produce sections for electron microscopy. In English, the instrument is called microtome, while the term microtomo is used in some languages.

Typical light microscopy sections are 1 to 10 micrometers thick, with paraffin sections commonly around 4 to 6 micrometers. Frozen sections prepared with cryomicrotomes vary in thickness and speed. Ultramicrotomy yields ultrathin sections of about 0.05 to 0.1 micrometers for transmission electron microscopy.

How it works: In paraffin processing, tissue is fixed, dehydrated, cleared, and embedded in paraffin; for frozen sections, tissue is snap-frozen. The specimen is mounted and advanced toward a sharp knife or the knife is translated past the specimen. The blade edge thickness, angle, and blade quality determine section integrity, and sections are floated on a water bath before mounting on slides.

Applications and uses: Microtomy is essential in medical diagnostic laboratories, biological research, and some materials science settings. It enables immunohistochemistry, routine histology, and analysis of morphological features. For non-biological materials, microtomy can prepare thin sections of polymers or composites for microscopy, though material properties limit cut quality.

Safety and maintenance: The blades are extremely sharp, and proper training, guards, and handling procedures are required. Regular maintenance includes blade replacement, alignment checks, and clean, dry storage to prevent corrosion and damage to the knife and specimen. The term microtomo is used in some languages to refer to this instrument.