Types Of Microtomes In Histopathology

This lecture helps to Define microtomy and microtomes, List the different types of them and Describe their functions.

1. Types of microtomes Neelain university Faculty of medical laboratory science Histopathology department By : Omnia Osman Sunday, April 12, 2020

2. Objectives : Define microtomy and microtomes. List the different types of microtomes. Describe their functions . Describe the differences between each microtome and another ! By the end of this lecture you should be able to : Sunday, April 12, 2020 types of microtomes / omnia osman

3. Microtomy and microtomes : Microtomy :Means by which tissue can be sectioned and attached to a surface for microscopy . Microtomes : The basic instrument used in microtomy . They are precision instruments used to cut uniformly thin sections of tissue, supported in its embedding medium. Sunday, April 12, 2020 types of microtomes / omnia osman

4. How does it work ? an advancing mechanism moves the object (paraffin block) for a predetermined distance until it is in contact with the cutting tool (knife or blade). The specimen moves vertically past the cutting surface and a tissue section is produced. Good technique is achieved through ongoing practice. Sunday, April 12, 2020 types of microtomes / omnia osman

5. Types of microtomes : Based on the mechanism : Rotary microtome Rocking microtome Base-sledge microtome Sliding microtome Freezing microtome Vibrating microtome Saw microtome Cryostst microtome Ultra- microtome Sunday, April 12, 2020 types of microtomes / omnia osman

6. Rotary microtome : Most widely used . often referred to as the “ Minot ” after its inventor. The knife is stationary and the block is moved up and down in a vertical plane by the rotary action of the hand wheel . Suitable for paraffin embedded sections. Sunday, April 12, 2020 types of microtomes / omnia osman

7. The rotary microtome may be: manual (completely manipulated by the operator) semi-automated (one motor to advance either the fine or course hand-wheel) fully automated (two motors that drive both the fine and the course advance hand-wheel). * Disadvantage : not suitable for large blocks or hard tissues. Sunday, April 12, 2020 types of microtomes / omnia osman

8. Rocking microtome : The oldest type of microtomes . The name comes after the rocking action of the handle . In this microtome knife is fixed and the block of the tissue moves through an arc tostrike knife . Sunday, April 12, 2020 types of microtomes / omnia osman -

9. Rotary rocking microtome : This is slightly more robust than the rocking microtome and has the advantages of producing a flat face to the tissue block . Most of the have a retracting mechanism which takes the tissue block away from the knife on the upward stroke. Although the can be used for paraffin wax work they are used more commonly in cryostats . Sunday, April 12, 2020 types of microtomes / omnia osman

10. Base sledge microtome : With the sledge microtome, the specimen is held stationary and the knife slides across the top of the specimen during sectioning. Used primarily for large blocks, hard tissues, or whole mounts it is especially useful in neuropathology and ophthalmic pathology. Sunday, April 12, 2020 types of microtomes / omnia osman

11. Sliding microtome : The knife or blade is stationary and the specimen slides under it during sectioning. This microtome was developed for use with celloidin-embedded tissue blocks. Sunday, April 12, 2020 types of microtomes / omnia osman

12. Vibrating microtome : Designed to cut fresh unfixed tissues. The name of the instrument derives from the high speed vibration produced in a safety razor blade to provide the cutting power . The amplitude of vibration is adjusted by altering electrical voltage applied to the knife. Sunday, April 12, 2020 types of microtomes / omnia osman

13. Ultra microtomes : These are used exclusively for electron microscopy . It has been reported that sections can be cut as thin as 10 nanometers . Knifes are usually made from glass or diamond . The block is brought to the knife edge under microscopical control and as each section is cut it is floated on to a water bath adjacent to the knife edge . Sunday, April 12, 2020 types of microtomes / omnia osman

14. Freezing microtome: This form of microtome is used for cutting thin to semi-thin sections of fresh frozen tissue . Although other microtomes can be modify for cutting frozen section , this type will give the best results and is used almost universally . Sunday, April 12, 2020 types of microtomes / omnia osman

15. Sunday, April 12, 2020 types of microtomes / omnia osman Any Questions ?

16. Reference : Bancroft’s Theory And Practice Of Histological Techniques/S. Kim Suvarna- christopher Layton -John D. Bancroft Sunday, April 12, 2020 types of microtomes / omnia osman

17. Sunday, April 12, 2020 types of microtomes / omnia osman Thank you For your attention