Exercise 1 - Microscopy

STUDENT OBJECTIVE

Students learn the parts and functions of compound and dissecting microscopes and view various specimens. Using a stage micrometer, students calibrate an ocular micrometer. Students also learn how to measure the size of structures shown in scanning and transmission electron micrographs.

EQUIPMENT AMOUNT (Class of 24 with 8 groups)
Compound microscope 1/student
Dissecting microscope 1/student
Ocular micrometer (can be set up as demonstration) 1/student
Stage micrometer (can be set up as demonstration) 1/student


MATERIALS

Electron micrographs Five to ten large posters made with photos
from textbooks--include a variety of cells
from different organisms 		Display
Ruler, 15 cm clear plastic in mm 12/lab
Scissors and dissecting needles 12/lab
Old newspapers for letters "e" and "a" 6/lab
Red and white thread 1 spool/lab
Forceps 6/lab
Blotting tissue 2 boxes/lab
Slides 2/student
Coverslips, #1 small square 1/2 oz/lab
Lens tissue, 2" x 4" (cut from standard tissue package) 8 pkg/lab
Dropper bottle with distilled water 8/lab
Specimens for dissecting scopes Variety of dead insects, flowers, seeds
Immersion oil (if oil objectives are used) 8 bottles/lab

PREPARATION

At Least One Week before Lab

Microscopes should be checked for repair or replacement and supplies ordered. Dried insects, flowers, seeds, and such can be collected at this time.

CLASSROOM SUGGESTIONS

  1. A display can be made including scanning and transmission electron micrographs, pictures of microscopes, and associated equipment. These can be obtained from the library, advertising pamphlets, and catalogs.

  2. Films or slides on microscopy may be used to augment the exercise.

  3. This exercise is short and can be done in conjunction with Exercise 2 to fill a three-hour lab period.

ANSWERS TO CRITICAL THINKING QUESTIONS

  1. Adjust the interpupillary distance of the eyepieces to correspond to your interpupillary distance by moving the eyepieces closer together until the two separate circles of light merge.

  2. Use a dissecting microscope to observe the sea star and the live fruit fly. Use a compound light microscope to look at the fruit fly chromosomes. Do not use an electron microscope to view anything living. The fixing and infiltration procedures "kill" the tissue.

SUPPLEMENTAL MATERIALS

Bio Sci II, videodisc contains sequences on using microscope. Dubuque, IA: Wm. C. Brown Publishers. See appendix.

Electron Microscopy, 15 minute film. Ames, IA: Media Resources Film Library, Iowa State University. #S20725F

Introduction to Microscopy, filmstrip. Burlington, NC: Carolina Biological Supply. #52-2008

Microscopes, slide set. West Los Angeles, CA: Science Software Systems, Inc. #200-0185

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