LAB 2: MEASUREMENT AND COUNTING OF CELLS USING MICROSCOPE

2.1 OCULAR MICROMETER

INTRODUCTION

An ocular micrometer is a glass disk that fits in a microscope eyepiece that has a ruled scale, which is used to measure the size of magnified objects. The physical length of the marks on the scale depends on the degree of magnification.

OBJECTIVE

To measure and count cells using a microscope

MATERIALS AND REAGENT

Microscope fitted with an ocular micrometer

Slide micrometer

Stained preparation of yeast and bacteria

PROCEDURE

(refer to lab manual)

RESULT

Total magnification = objective lens power x eyepiece lens power(10x)

The ratio of magnification was calculated by:

the observed  diameter of yeast is 1mm ocular

Using 40x magnification,

1mm on stage represent 8.9mm on eyepiece under 40x magnification view

Magnification	Ocular(mm)	Stage(mm)
10x	0.89	0.1
40x	8.9	1.0

CONCLUSION

The size of the microorganism can be measured by using ocular micrometer and stage micrometer.

REFERENCES

http://en.wikipedia.org/wiki/Ocular_micrometer

http://www.mecanusa.com/microscope/micrometer/micrometer-use_en.html

2.2 NEUBAUER CHAMBER

INTRODUCTION

The hemocytometer is a device used to count cells. It was originally designed for the counting of blood cells.

The hemocytometer was invented by Louis-Charles Malassez and consists of a thick glass microscope slide with a rectangular indentation that creates a chamber. This chamber is engraved with a laser-etched grid of perpendicular lines. The device is carefully crafted so that the area bounded by the lines is known, and the depth of the chamber is also known. It is therefore possible to count the number of cellsor particles in a specific volume of fluid, and thereby calculate the concentration of cells in the fluid overall.

MATERIALS AND REAGENTS

Serial dilutions of bacteria cultures
Neubauer and coverslip
70% ethanol
Sterile Pastuer pipettes

PROCEDURE

(refer to lab manual)

RESULT

Number of cell = 1550

Boxes = 5

1550 = 310 (average for 1 box)

   5

Total 256 small box = 310 x 256

                               = 79360

Volume       = 1 x 1 x 0.1

                   = 0.1mm³

1mm³              = 0.001cm³

0.1  mm³         = 1 x 10^-4mL

1 x 10^-4 cm³ = 1 x 10^-4mL

79360

1 x 10-4mL

 Concentration =

                        

                         = 793 600 000

CONCLUSION

By using the neubauer chamber, we can estimate and hence calculate the number of microorganisms

REFERENCES

http://www.microbehunter.com/the-hemocytometer-counting-chamber/
http://groups.molbiosci.northwestern.edu/morimoto/research/Protocols/II.%20Eukaryotes/A.%20Cell%20Culture/3b.%20Hemacytometer.pdf