2.1.1(B) the preperation and examnation of microscope slides for use in light microscopy

How do you increase the mag power?

Higher power objective

How do you prepare slide using liquid specimen?

Add a few drops to slide using a Pipette

Cover liquid with a coverslip and gently press down to remove air bubbles

Wear gloves

How do you prepare a slide with a SOLID specimen?

WEAR GLOVES TO PREVEN SKIN STAIN

Use scissors to cut a small sample of tissu

Peel a very thin layer of cell from the tissue sample

Stain

Coverslip+ press down = no bubbles

Why does the tissue need to be thin for a solid specimEn?

Light needs to pass through from the microscope

What are the STEPS FOR USING A LIGHT MMIRCROSPPE (OR OPTICAL)

Start with low power obj lens

• Prevents damage to lens or coverslip in case the stage has been raised too high.

Prevent dehydration

• Thin layers dry rapidly

• Add a drop of water to specimen can prevent cells from being damaged by dehydration

If unclear or blurry

• Lower power objective + try using the coarse focus

• Cross contamination with foreign cells

• Is specimen thin enough to get light through

What is a graticule?

A small disc with engraved ruler which is placed into eyepiece of microscope to be able to measure the size of specimen viewed under a microscope.

Why is the graticule calibrated?

Values of the divisions in an eyepiece graticule vary depending on the magnification used

How is the graticule calibrated?

Done using a STAGE MICROMETER

This is a slide that contains a tiny ruler with an accurate known scale

They often have larger divisions of 0.1nm and smaller divisions of 0.01mm

What is the limitations of graticule?

Size

• Inconsistent in diff spec slides

Diff size tissue samples (cut differently) which could mean inconsistencies when viewed in 2 D

Might not be same mag power

The treatment of specimens when preparing may alter the structure of cells