MadSci Network: Cell Biology
Query:

Re: What is the difference between male and female cheek cells?

Date: Tue Jun 8 09:26:47 1999
Posted By: Leslie Gartner, Faculty Histology/Anatomy, University of Maryland, Baltimore, MD
Area of science: Cell Biology
ID: 926271804.Cb
Message:

Dear Sumnima,

The question that you ask is really interesting because it has direct 
application for the upcoming Olympics games. One of the ways that the 
gender of a female athlete is ascertained is by taking a scraping of the 
lining of the cheek and examining the cells under the microscope.

As you correctly pointed out cells from a female possess two X chromosomes 
whereas cells from a male would possess a single X and a Y chromosome. It 
is great to know that bit of information, but you need to look a little 
further about chromosomes. Unless the cell is undergoing mitosis (or 
meiosis in the case of gametes), the chromosomes of these cells are mostly 
unwound. You can think of them as a long piece of yarn that, instead of 
being rolled into a ball, is loosely arranged in the nucleus. This is true 
for all of the chromosomes, except for the second X chromosome of the 
female. It is present in its condensed state, that is it is wound up in a 
little ball. So when you look at the nucleus of the cheek cells, most of 
the female's cheek cells will have a little dense, dark spot at the 
periphery of the nucleus, whereas only a few of the male's cheek cell 
nuclei will have one of those little spots. These little spots are known as 
"sex chromatin" or "Barr body." So the cell itself is not darker, only that 
little spot in the nucleus is darker.

Although you didn't ask, all of the females cells that have nuclei will 
exhibit a sex chromatin and if you look at a female's neutrophil, one of 
the white blood cells, the sex chromatin is located in an outpocketing of 
the nucleus. This outpocketing resembles the drumstick of a chicken and is 
referred to as the "drumstick." 

I hope this helps. Good luck.

Leslie P. Gartner, Ph.D.
Associate Professor of Anatomy
Dental School
University of Maryland


Current Queue | Current Queue for Cell Biology | Cell Biology archives

Try the links in the MadSci Library for more information on Cell Biology.



MadSci Home | Information | Search | Random Knowledge Generator | MadSci Archives | Mad Library | MAD Labs | MAD FAQs | Ask a ? | Join Us! | Help Support MadSci


MadSci Network, webadmin@www.madsci.org
© 1995-1999. All rights reserved.