Sizes and Rates

APh 162: Weeks 1 & 2

E.WM Fong, JH Kim, AP Lin





About Us













Microscopic Studies of Various Organisms


Microscopy is a useful tool commonly used in understanding cell biology. In this session, techniques such as dark field, bright field and fluorescent imaging were introduced, and the importance of scale bars and calibrations was strongly enforced. A feel for the dimensions and scale of things was also extensively explored.



1) Calibration of individual microscopes was carried out using a stage micrometer for different magnification powers (i.e. 10x, 20x, 40x and 100x).

2) Various organisms are placed on glass slides, and covered with glass coverslips and observed under various magnifications.

3) Using Image J, the pixels on the images can be calibrated to the actual dimension of the specimen.


Results and Discussion:

Four organisms were studied under various microscopes and magnifications:

a) Stentor: The largest single-celled protozoa found in water. Interesting features such as propelling cilia, contractile vacuoles and macronuclei were quantitatively observed.  Dimensions are characterized in the table below.  Images were acquired on a Zeiss Axio microscope at 10x magnification.


Average Dimensions

Length of stentor

1 mm

“Trumpet” region

350 microns

Contractile vacuoles

110 microns

Macronucleii (beads on a string)

33 microns

Click on figure below for movie (9 MB):

b) Fibroblast: Derived from mesenchymal tissue, fibroblasts are building blocks for structural fibers and connective tissues. Features such as cytoplasm, nucleus and cell spreading were observed. The diameter of a nucleus is about 13 microns and the average length of a cell ranges from 25-50 microns.  Images were acquired at 100x magnification on an Olympus CX41 microscope using Moticam 1000 camera and software.

c) C. Elegans: First ever to have its genome sequenced. Features such as the mouth, pharynx, intestine, gonad, and collagenous cuticle were observed. Speed of C. elegans movement was also calculated. The length of these C. Elegans can range from 210 – 464 microns, with the average body length of 79 microns. Images were acquired at 10x magnification on an Olympus CX41 microscope using Moticam 1000 camera and software.

d) E Coli (bacteria): Most commonly studied prokaryote. Stained with green fluorescent protein (GFP), E coli cells were visualized under the Zeiss microscope. Photobleaching and the movement of E coli cells were also observed. The average length of an E coli cell ranges from 1.4 – 6.7 microns. Images were acquired on an Zeiss Axio microscope at 40x and 100x magnification.


More samples could be measured to give a more accurate picture of the average dimensions of each organism. To overcome fast photo bleaching of the GFP-E coli cells, cells should be located on bright field mode, before rapidly switching to fluorescent mode to obtain a picture.


Frontpage Templates and Themes

Copyright KimFongLin 2006