4. Taking Samples:
Edge of lesions.
 Wall of cysts.
 Whole specimen if
 Direction, mark
5. Inking the Margins
 To mark surgical
 Spread of lesion
 Adequacy of
 Different colors to
 Specimen bits are
placed in porous
 Not more than 5mm
 In 10% formalin
 1mm/hour fixation
 ~ 6 hour
7. Types of fixative:
 Acetic acid
 Methanol and Picric acid.
A. Definition: removal of water
B. Rationale: for paraffin embedding/sectioning
1. wash out fixative
2. graded series of alcohol
 70%, 95%, 100%, 100%
3. replace water by diffusion
4. not too long, not too short
• replacing the dehydrating fluid with a fluid that is totally
miscible with both the dehydrating fluid and the embedding
Choice of a clearing agent depends upon the
- Intended processing conditions such as temperature,
vacuum and pressure.
- Safety factors.
- Cost and convenience.
- Speedy removal of dehydrating agent .
- Ease of removal by molten paraffin wax .
- Minimal tissue damage .
11. is the process by which tissues are
surrounded by a medium such as agar,
gelatin, or wax which when solidified will
provide sufficient external support during
• 1. Place tissue cassette
in melted paraffin
• 2. Fill mold with
• 3. Place tissue in
• 4. Allow to cool
A. Orient tissue
1. cross section
2. longitudinal section
B. Dissection orientation
C. Avoid bubbles
14. Precaution while embedding in wax
 The wax is clear of clearing agent.
 No dust particles must be present.
 Immediately after tissue embedding, the wax must be rapidly
cooled to reduce the wax crystal size.
15. There are four main mould systems and associated
embedding protocols presently in use :
• 1- traditional methods using paper boats
• 2- Leuckart or Dimmock embedding irons or metal containers
• 3- the Peel-a-way system using disposable plastic moulds and
• 4- systems using embedding rings or cassette-bases
 Paraffin block with
 consistency to cut
 Paraffin blocks taken