Gary, your problem is a classical stereology one, well described in many books and articles. Howard and Reed : Unbiased Stereology or Peter Mouton: Principles and Practices of Unbiased Stereology are good starting material. A correct, by modern stereology rules, approach would have required 3D counting, either in thick sections or 2 thin sections.
For your question, an Abercrombie correction might help:
N=c*(h/(h+z))
where N is the real number of particles, c is the number of profiles counted in a thin section, h is the thickness of the section (2 in your case) and z the mean z dimension of cells. You can change z by 7% and find out how much N changes.
One of the several problems with this approach is the fact that you don't actually know z.
Does this help?
>>>
[hidden email] 11/03/05 12:50 PM >>>
My name is Gary Hradek and I work at UCSF.
I am trying to measure the difference between ears
that have been treated with GM1 in a deafness study.
Normal ears have a fixed number of neurons with an
average cross-sectional area of 320 micrometers.
Deaf ears have fewer and smaller neurons.
I have used a counting method that measures the
density of the neurons(neuron profiles) in 2 micron
sections by overlaying a grid matrix on the section
and counting the times the intersection appear over
the neuron(point counting). I have used image J to
measure the cells and the deafened GM1 treated cells
are 7 percent smaller than the deafened controls.
What is the proper correction factor to use?
Bigger cells will have a larger cross-sectional area(x
and y dimension) and more profiles in the z dimension.
Both of these factors will affect my density
measurement. I think that 7 percent account for the x
and y difference. I think I need to add one half of
7 percent or 3.5 percent to account for the z
difference. The total correction would be 10.5
percent? Any suggestion would be greatly appreciated
and many thanks for your considerations. Gary
__________________________________
Yahoo! FareChase: Search multiple travel sites in one click.
http://farechase.yahoo.com
Locked
