Microtomy is the process of cutting very thin sections of tissues or other materials for examination under a microscope. There are several types of microtomes that cut sections of varying thickness depending on the material and intended use. The most common type is the rotary microtome, which uses a rotating blade to cut sections at predetermined thicknesses. Specimen preparation involves fixation, processing, dehydration, clearing, embedding, section cutting, and staining to produce slides ready for analysis.

1. Microtomy
Biological Techniques

2. What is microtomy?
Introduction

3.  Thickness of the sections is predetermined at regular
distance on the microtome
 The sections are attached to a surface like glass slides
for staining
 Tissues like muscles, bones, hair are cut of thickness
from 50 nm and 100 µm
 Thickness of the sections may be fixed according to the
need of the study and material involved
 The stained sections can be studied by light or electron
microscopy
Introduction

4. Advanced Analytical Techniques
Microtomy- Types of
microtomy

5. Types of microtomy
 Main types include
◦ Rotary microtome
◦ Cryotome
◦ Ultra microtome
◦ Laser microtome
 Use depends on the material under study and the
nature of the work
 Simple studies involve rotary microtome while
detailed studies may involve ultra microtome, etc.
 Similarly cryomicrotome involves sectioning of the
frozen tissues.

6.  The most common type of the microtome
 Rotary action involves the sectioning process at
predetermined thickness on every rotation of the
flywheel
 Blade is fixed at horizontal position
 The sample holder moves the sample ahead by the
fixed distance for cutting
 Flywheel of the instrument may be automatic or
manual
 Section thickness may vary from 0.5 µm to 60 µm
Types of microtomy

7. Types of microtomy
 Used for making extremely thin sections (40 nm to
500 nm)
 Used mostly for biological samples but samples may
also be processed
 Linear thermal expansion moves the specimen at
regular interval
 The sections are studied in transmission or scanning
electron microscopy
 The cut sections are floated on the top of a liquid
 These are then mounted on a copper, nickel, gold, or
other metal grid

8. Advanced Analytical Techniques
Microtomy-
Method (fixation
and processing)

9.  It consists of following main steps
 Fixation
 Processing
 Dehydration
 Clearing
 Embedding
 Section cutting
 Staining
 Deparaffinization
Method (fixation and processing)

10. Fixation
Method (fixation and processing)

11.  Commonly used fixatives are alcohol,
formalin, glutaraldehyde, etc.
 Factor affecting fixation are temperature,
change in pH, penetration of the fixative,
volume, time, etc.
 The lowest concentration of the fixative is
preferred than the higher one
 10% formalin or 2.5% glutaraldehyde is used
Method (fixation and processing)

12. Processing
Method (fixation and processing)

13. Advanced Analytical Techniques
Microtomy-
Method
(embedding)

14. Embedding
Method (embedding)

15. Method (embedding)

16. Method (embedding)

17. Advanced Analytical Techniques
Microtomy-
Method
(sectioning and
staining)

18. Sectioning
Method (sectioning and staining)

19. Sectioning
Method (sectioning and staining)

20. Staining
Method (sectioning and staining)

21. Staining
Method (sectioning and staining)