EMBEDDING - TRIMMING - SECTIONING - MICROTOME Flashcards
Aka: Casting/Blocking
EMBEDDING
● Process by which the impregnated tissue is placed into a precisely arranged position in a mold containing a medium which is then allowed to solidify
EMBEDDING
○ Process by which a tissue is arranged in precise positions in the mold during embedding,
■ On the microtome before cutting and on the slide before staining
● Orientation
The surface of the section to be cut should be placed parallel to the bottom of the mold in which it is oriented
EMBEDDING
Temperature of melted paraffin used for embedding
5-10℃ above its Melting Point
What is the other name of “Embedding”?
According to Gregorios it is otherwise
known as “Casting” or “Blocking”
To solidify embedded tissue
Cooled rapidly in a ref (-5℃) or immersed in cold water
STEPS IN EMBEDDING
- Removed the tissue from the cassette
- Fill the mold with wax
- Orientate the tissue
● Process of removing excess wax after embedding.
TRIMMING
is performed in the paraffin oven.
Embedding
● The excess wax is cut off from the block to expose the tissue surface in preparation for actual cutting.
● Knife/Blade may be used.
TRIMMING
Correct shape of the block:
Four-sided prism or Truncated pyramid
● Also known as cutting or microtomy
SECTIONING
● The process by which a processed tissue is cut into
uniformly thin slices (sections) to facilitate studies under the microscope.
○ Sections (Gregorio’s) or Ribbon
SECTIONING
Routine tissue microtomy
3 - 5 u
Frozen sections
10 - 15 u
Very thin sections
- For electron microscopy
60 - 100 nm
Semi-thin sections
- For electron microscopy
0.5 - 1 um
● For cutting serial sections of large blocks of paraffin-embedded tissues
● The simplest microtome
Rocking Microtome
Inventor of Rocking Microtome
Paldwell Trefall in 1881
Disadvantage:
● Difficulty in re-orienting the block
Rocking Microtome
● For cutting paraffin-embedded
sections
Rotary / Minot Microtome
Inventor of Rotary / Minot Microtome
Minot in 1885-1886
● The most common microtome used today especially for paraffin-embedded tissues
Rotary / Minot Microtome
Some microtomes have digital
indicators to adjust the thinness of the sections to be cut.
Rotary / Minot Microtome
● For cutting celloidin-embedded
sections
Sliding Microtome
Inventor of Sliding Microtome
Adams in 1789
The most dangerous type due to
movable exposed knife
Sliding Microtome
2 types of Sliding Microtome:
- Base-Sledge
- Standard Sliding Microtome
can be used for all types of media
- Block holder: moving
- Knife: stationary
Base-Sledge