NOVA Online (see text links below)
Sex: Unknown  
How Is Sex Determined?


A sperm enters an egg cell and the egg is fertilized.

As with all other eggs in a woman's body, the cell contains one female-determining X chromosome. A sperm cell, however, may contain either an X chromosome or a Y chromosome. If the fertilizing sperm cell contains an X chromosome, the egg will develop into a female. If it contains a Y chromosome, it will develop into a male.

Note: It is possible, however, that a fertilized egg cell containing a Y chromosome will develop into a female or an intersexual (person of ambiguous gender). For example, if the Y chromosome is missing the SRY gene, which is located near the end of the short arm of the chromosome, the egg will develop into a female.

Back | Next: Week 3

Printer-Friendly Format   Feedback

My Life as an Intersexual | Share Your Story | Two Sexes Are Not Enough
The Intersex Spectrum | How Is Sex Determined? | Resources
Transcript | Site Map | Sex: Unknown Home

Search | Site Map | Previously Featured | Schedule | Feedback | Teachers | Shop
Join Us/E-Mail | About NOVA | Editor's Picks | Watch NOVAs online | To print
PBS Online | NOVA Online | WGBH

© | Updated October 2001
Shop Teachers Feedback Schedule Previously Featured Site Map Search NOVA Home Sex: Unknown Home Sex: Unknown Home Site Map