Micrometry and microscopy, Essays (university) of Biology

Download Micrometry and microscopy and more Essays (university) Biology in PDF only on Docsity!

Zoology 111.1 – Invertebrate Zoology Score:

MICROMETRY AND MICROSCOPY

Avisado, Luzadas, Mangalino, Montoya, Payopay

Krusty Krabs

Abstract Microscopy is the science that deals with the use of the microscope, a tool used to enlarge microscopic objects. A useful field in microscopy is micrometry. Micrometry deals with the measurement of the dimensions of a microscopic object under the microscope using microscales. In this experiment, the researchers used techniques in microscopy to measure the dimensions of a Paramecium sp., a microscopic organism. They used the ocular and stage micrometers to properly calibrate both the microscope’s low and high power objectives. In doing this, they found out that the calibration constant between the two lenses were different.

I. Introduction

Microscopy is the field of science which uses a special instrument known as microscope which is helpful in viewing objects and areas of objects that cannot be seen with the naked eye. A microscope is an optical instrument used for viewing very small objects such as animal and plant cells, mineral samples and many others and can also be magnified several hundred times. This is used to study microorganisms and also the dimensions of the microorganisms.

Micrometry came from the words “micro” which means microscopic and “metry” which means measurement. It is the measurement of the dimensions of microscopic objects in terms of length, diameter, breadth and thickness. This is helpful in measuring very small organisms that are not visible to naked eye and can only be observed under the use of a microscope.

Measurement of the dimensions of microorganisms is done under a microscope with the

help of microscales called micrometers, the ocular micrometer and stage micrometer. The ocular micrometer is a circular glass disc which fits into the circular compartment inside the eyepiece. The other one which is the stage micrometer is a special glass slide which is clipped to the stage of the microscope and has a standard graduation of 10 μ apart. Both the micrometers have microscopic graduations etched on their surfaces.

The calibration of the microscope is important in the measurement of microorganisms because the distance between ocular graduations varies depending on the objective being used which determines the size of the field. The graduations on the ocular micrometer are calibrated against the standard graduations on the stage micrometer using a required objective. For the calibration, both the micrometer etchings are superimposed by rotating the eyepiece so that the number of ocular divisions (O.D.) coincides with the number of stage divisions (S.D.).

The objectives of this experiment are as follows; (a) to be familiar with the parts of the microscope and their corresponding functions, (b) to apply the proper ways of handling and carrying a microscope, (c) to view a Paramecium sp. slide under LPO and HPO, and (d) to measure the size of each cell under the microscope.

II. Methodology The exercise, measuring of cells with the help of an ocular micrometer, required each group to have a microscope along two prepared slides, an ocular disc scale or micrometer and a stage micrometer, which were distributed by the faculty- in-charge.

The measurement of the cells began by first placing the stage micrometer on the microscope’s stage. The ocular disc scale was then adjusted to be exactly superimposed with the zero line of the stage micrometer scale. The numbers of spaces or divisions of the stage micrometer were then counted starting from the zero line to the superimposed line. The number of ocular divisions from the zero line to the superimposed line was also counted repeating around 3 times. With the values taken, the calibration constant is calculated by dividing the number of stage micrometer spaces by the number of ocular micrometer spaces multiplied by 10 micrometer.