Microtomy Flashcards
microtomy: process whereby the tissues are _____ into uniformly thin slices or sections to facilitate the studies under microscope
trimmed and cut uniformly
process whereby the excess wax is cut off from the block to expose the issue surface in preparation for actual cutting
trimming
process whereby the tissues are cut into uniformly thin slices
sectioning/section cutting
sliding microtome was developed by ___ in _____.
Adams in 1789
two types of microtome
- Base-sledge microtome
- Standard sliding microtome
sliding microtome is for cutting ___
celloidin embedded sections
this microtome is used in lab for sectioning very hard tissue or blocks. most dangerous because of its movable exposed knife.
base-sledge microtome
rotary microtome was developed by ___ in ____
minot in 1885-1886
rotary microtome is for?
cutting paraffin embedded sections
most popular microtome and the most common type used for routine and research studies.
rotary microtome
rocking microtome also known as the ____ was developed by ___ and ____ in 1881
Cambridge
developed by Paldwell and Trefall
rocking microtome is the simplest used for cutting ____ of paraffin embedded tissues
serial sections of large blocks
freezing microtome was invented by ___ in ___
Queckket in 1848
freezing microtome is replaced in most lab by the ___ which is easier to operate
cryostat
ultrathin microtome is used for cutting specimens intro extremely thin slices ____ for ____ microscopy.
0.5u for electron microscopy
enumerate the types of microtome knives
- place concave
- biconcave
- plane wedge
biconcave is used in ____ microtome, ____ in length
used in rotary microtome, 120mm in length
concave side is for the ___
flat/straight for ____
both sides straight ____
concave: paraffin sections
flat/straight: celloidin tissues
both sides straight: frozen sections/hard specimens
plane concave knife is used for what microtome?
- Base-sledge/sliding microtome
- rocking microtome
- rotary microtome
plane wedge knife is used for?
- Base-sledge/sliding microtome
LENGTH:
plane concave:
plane wedge:
plane concave: 25 mm in length
plance wedge: 100 mm in length
paraffin thickness
4-6 u thick
enumerate the type of tissue sections
- Parrafin section
- Celloidin
- Frozen
paraffin section may be cut by?
rotary and rocking microtome
celloidin section thickness
10-15 u thick
celloidin section is used by means of the ____ microtome
sliding microtome
used to remove the gross nicks and irregularities on the knife
honing
direction of honing
heel to toe (edge first)
types of hone
- carborundum
- arkansas stone
- yellow belgian/belgium
- belgian black vein
hone used only for badly nicked knives
carborundum
arkansas stone is a stone for?
medium fineness
belgian black vein is also called __
oil stones
the finest hone which gives the best result
yellow belgian/belgium
enumerate the oils used in belgian black vein
- light machine oil
- liquid paraffin oil (mineral oil)
- vegetable oil
- xylene (evaporates easily)
- natural oil (messy)
process whereby the burr formed during honing is removed and the cutting edge of the knife is polished
stropping
direction of stropping of stropping and the purpose
direction: toe to heel (edge last)
purpose: polish and sharpen the knife
used to flatten sections
floating-out bath
floating-out bath is aa circular, thermostatically controlled bath ____ in diameter and ____ in depth
10-12 inches in diameter
3-4 inches in depth
t or f: the inside surface of a floating-out bath is clear thus enabling easier visualization of sections
false, inside surface of a floating-out bath is black
for the floating-out bath, thermostat should be set at ___C about ___C below the melting point of the wax
be set at 45C (45-50 C) about 10C (6-10C)
used for fluorescent antibody staining techniques or histochemical studies, for rapid preparation of urgent tissue biopsies
cryostat/cold microtome
the microtome inside the cryostat
rotary
2 methods of staining in cryostat sections
- H&E staining
- Polycrhome methylene blue (Loeffler’s polychrome methylene blue)
this is utilized when a rapid diagnosis of the issues is required and is essentially recommended when lipids and nervous tissues elements are to be demonstrated
frozen sections
advantages of frozen sections
- For certain staining procedures:
- demonstration of fat by the Oil Red O methid
- silver impregnation method (CNS/Neuropathology)
- immunofluorescence and immunocytochemical staining - essential for rapid diagnosis during operation
enumerate the 2 methods of preparing frozen sections
- cold knife procedure
- cryostat procedure (cold microtome)
enumerate the commonly used methods of freezing
- liquid nitrogen
- isopentane cooled by liquid nitrogen
- carbon dioxide gas
- aerosol sprays
special processing techniques
freeze drying and freeze substitution
preserving tissues by rapid freezing (quenching) and removing water (dessication) by a physical process without the use of any chemical fixative
freeze drying
freeze drying tissue size
2 mm thick
complete processing time of freeze drying
24 - 48 hrs
in freeze substitution, tissue is fixed in ____ or in ____ and dehydrated in absolute alcohol
Rossman’s fluid or in 1% acetone
Rossman’s fluid components
saturated picric acid + formaldehyde
