5-MICROTOMOY Flashcards
What is the process of trimming and cutting processed tissue
most commonly paraffin-embedded tissue
What is the simplest type of microtome used for serial sections of large blocks of paraffin-embedded tissues?
Rocking (Cambridge) Microtome
What is the most common type of microtome used in histopathology for paraffin-embedded sections?
Rotary Microtome
What section thickness does a rotary microtome typically cut?
3-5 µm (or 4-6 µm in some references)
What are the key components of a rotary microtome?
Knife holder base+knife holder+knife blade+mounting device+course and fine trimming wheels+safety locks
What is the function of orientation screws in a rotary microtome?
Aligning and centering the block without compensating for unacceptable embedding
What type of microtome is used for celloidin-embedded sections?
Sliding Microtome
What type of microtome is used for unembedded frozen sections?
Freezing Microtome
What type of microtome is used for frozen sections at temperatures between -5°C to -30°C
ideally -30°C?
What are cryostat microtomes commonly used for?
Urgent biopsies+intraoperative diagnosis+fluorescent antibody staining+histochemical enzyme studies
What type of microtome cuts ultra-thin sections (60-100 nm) using glass or gem-grade diamond knives?
Ultrathin Microtome (used for electron microscopy)
What are the three profiles of microtome knives and their uses?
Plane concave: celloidin or paraffin sections+biconcave: embedded sections on rotary microtomes+plane wedge: frozen sections or hard specimens on base-sledge/sliding microtomes
What is the cutting tool made of stainless steel
placed on the microtome via the blade holder
What coating may be applied to microtome blades to reduce resistance during sectioning?
Polytetrafluoroethylene (PTFE)
What are the advantages of microtome blades?
Constant sharp edge+ease of use+adaptability to various tissue types+low cost compared to steel knife sharpening
What are the two profiles of microtome blades and their uses?
Low-profile blades: rotary microtomes+High-profile blades: cryostats
What angle is formed between the cutting edges of a microtome blade?
Bevel angle (normally 27° to 32°)
What is the angle at which the blade hits the block surface during sectioning?
Clearance angle (optimal: ~3-8°
How is the clearance angle set on a microtome?
Using the clearance angle gauge on the knife holder
What equipment is used for honing non-disposable blades?
Belgium yellow stones+Arkansas stones+Fine carborundum stones
What is honing used for?
Removing gross nicks and grinding the knife edge to acquire an even edge
What process removes burrs formed during honing and polishes the cutting edge of a knife?
Stopping (using a paddle stop made of horse leather)
What are other essential tools used in section cutting?
Water bath+drying oven/hot plate+forceps+clean slides
What is the process of cutting tissues into uniformly thin slices using a microtome?
Sectioning
