Light Microscopes - Setting up a light microscope and preparing a temporary slide.

Filter paper

Method – Setting up a light microscope

1. The microscope was checked that it was on low power.
2. The microscope slide was secured on the stage with the object inline with the centre of the stage.
3. The coarse focus knob was turned so that the objective was as close to the microscope slide as possible.
4. The slide was focused away until the object was in focus.
5. The revolving turret head was turned until the high power objective (x40) was in line with the stage.
6. Using the fine focusing knob, the image was focused until the object was sharp.

Method – Preparing a temporary slide

1. An onion bulb was cut through vertically and one of the leaves of the bulb was separated off.
2. The inner surface was carefully peeled off with a pair of fine forceps.
3. A small piece of the epidermis (5mm x 5mm) was cut.
4. A pipette was used to carefully place a drop of water on a clean microscope slide.
5. The epidermis was carefully placed in the drop of water.  A mounted needle was used to flatten it.
6. A cover slip was placed on top of the epidermis, to make sure that the tissue was kept flat.
7. A drop of iodine solution was placed on one side of the cover slip.
8. The cut edge of a piece of filter paper was placed to the other side of the cover slip to draw small amounts of stain beneath the cover slip.
9. It was viewed with a microscope with low and then high power.

            Results

                                                                     

                                                            

Evaluation

Peeling the onion skin was the easy part but looking at the microscope was hard because the onion was thin and it kept folding over.  The strengths of this technique are that it’s safe and cheap.  The weaknesses were that the gas let off by the onion brings tears to eyes and having enough equipment, it was also difficult to focus on a high magnification.  Sources of error may occur if the microscope if not used properly.  I would make improvements to this technique by using a better stain that shows the details of the stain better, I’d use a better microscope and finally link the microscope to a computer to see the picture onscreen.

Discussion of Vocational implications

Different types of microscopes can be used to examine food, human cells and solve crimes.  Microscopes are an essential tool in medicine and can be used to identify the causes of many types of deadly diseases.  Scientists can also use a microscope to find out where illegal drugs come from.

In a college laboratory, laboratory slides are made as temporary slides, but in a pathology laboratory, slides must be made as permanent slides so they would be useful for future reference.  In a college laboratory, invisible cells are stained with methylene so they can be seen easier but in a pathology laboratory, haematoxylin is used for the nucleus and feulgen is used for the chromosomes.