LAB 1: 1.2

1.2 Examination of cells.

Introduction.

Since bacteria are extremely small, they are not usually being studied with the low power dry objectives or high power dry objectives but instead they are stained and observed with oil immersion objectives.

An oil immersion lens are used when you have a fixes ( dead-not moving) specimen that is no thicker than a few micrometers. Even then, use it only when the structures you wish to view are quite small- one or two micrometers in dimension. Oil immersion is essential for viewing individual bacterial or details of the striations of skeletal muscle. It is nearly impossible to view living, motile protist at a magnification of 1000x, except for the very smallest and slowest. 

A disadvantage of oil immersion viewing is that the oil must stay in contact, and oil is viscous. Oil distorts images seen with dry lenses, so once you place oil on a slide, it must be cleanned off thoroughly before using the high dry lens again. Oil on non-oil lenses will distort viewing and possibly damage the coatings. 

Steps in placing oil immersion.

The other method in observing the specimen is using the wet mount method. In a wet mount, the specimen is suspended in a drop of liquid ( usually water ) located between slide and cover glass. The refractive index of water improves the image quality and also supports the specimen. In contrast to permanently mounted slides, wet mount cannot be stored over extended time periods, as the water evaporate.

Wet mount sample.

Results.

Clostridium perfringes
10 x 100

 

Discussion. 

By using the wet mount methods, the cell was observed in coccus shaped and colourless. The cell has a motility characteristic.

Conclusions.

The image of moving stained microorganism also can be captured clearly through 10x objective X 10x eyepiece=100x magnification bright microscope. It also can use the highest resolving power to demonstrate these preparations because of their thinness. The deformation of light path is minimum as there are need be only one layer of differing refractive index, if oil-immersion objective and condenser is used. 

References.

http://www.microbiologyprocedure.com/microscopy-methods-in-microbiology/wet-mount-or-wet-film-preparations.html