Microscopy Maurice Wetherall University Senior College

Microscopy “This material has been developed as a part of the Australian School Innovation in Science, Technology and Mathematics Project funded by the Australian Government Department of Education, Science and Training as a part of the Boosting Innovation in Science, Technology and Mathematics Teaching (BISTMT) Programme.”

Microscopes Our knowledge and understanding of the structure of cells has only been possible as a result of the use of microscopes. Light microscopes were first used in the 16th century. The electron microscope was developed in the 1930’s.

Anton Van Leeuwenhoek’s Simple Microscope - 1670

An English Tripod Microscope from around 1680

A 19th Century Microscope

A Current Compound (Light) Microscope

Image From Light Microscope: Onion Root Cells X1000

Compound Light Microscope Light from a light source is directed through the specimen. A combination of lenses is used to increase the resolving power of the human eye up to 500 times. Resolving power (or resolution) refers to the ability to distinguish fine detail.

Compound Light Microscope The magnifying power is calculated by multiplying the individual powers of the eye-piece (ocular) and objective lenses. e.g. 10x eye-piece, 40x objective = 400x Field diameter is the actual distance across the field of view. As magnifying power increases the field diameter decreases proportionally.

Compound Light Microscope The amount of light passing through the specimen can be adjusted using the iris diaphragm. This changes the contrast. The condenser lens is used to concentrate light on the specimen.

Amoeba X1000 The following is a short movie of a living amoeba magnified 1000X through a compound light microscope An amoeba is a microscopic unicellular animal that lives in water Note the cytoplasmic movement, and also the way the whole cell moves.

Amoeba X1000

Phase Contrast Microscope This is a special type of light microscope, which provides greater contrast. Structures, which could not usually be seen without staining, show up. Staining cells kills the cells. Phase contrast microscopes can be used to observe living cells. e.g. movement of chromosomes during mitosis can be viewed.

Transmission Electron Microscope (TEM) In an electron microscope, beams of electrons are focussed using magnetic lenses. The resolving power produced is up to 500,000 times greater than the human eye. Because a vacuum is needed, tissue has to be specially prepared, and so living cells cannot be examined.

Transmission Electron Microscope (TEM)

Mitochondria The following slide shows mitochondria viewed through a transmission EM The internal structures of the mitochondria are visible. They are not visible through Light Microscopes.

Rough Endoplasmic Reticulum The following slide shows a section of rough endoplasmic reticulum. These flattened membranes are involved in synthesis and transport of proteins in cells. The small, dark dots are ribosomes.

Smooth Endoplasmic Reticulum

Electron Micrograph of Golgi Body

Scanning Electron Microscope An electron beam scans the surface of the specimen, Electrons are reflected off, and collected by a special electron detector. This provides an image, which appears on a computer screen and gives an impression of the outer shape of the specimen.

Scanning Electron Microscope at Adelaide Microscopy The following slide shows Year 11 students using one of the scanning EMs at Adelaide Microscopy.

Human Hair in a Scanning Electron Microscope The following specimens show human hair, the first one is hair in good condition and is from a person using shampoo and conditioner that are free of Sodium Laurel Sulfate and Propylene Glycol The second is of poor quality hair from a person using shampoo and conditioner containing Sodium Laurel Sulfate and Propylene Glycol

The End