Thread: What determines whether a fetus will become male or female?

I know it has to do with transcription of SRY that produces TDF (testis determining factor) and females don't have that gene in the first place, so what determines whether a fetus will have the sry gene or not?

The ovum (which has an X-chromosome) can be fertilized by either a Y-chromosome carrying sperm or by an X-chromosome carrying sperm. You'd need to read up on meiosis to see why normal sperm carry either an X or an Y. If the sperm that fertilizes the ovum carries a Y-chromosome then you have an XY individual (a male) - SRY is located on the Y chromosome. If an X-chromosome carrying sperm fertilizes the ovum the result is a cell with two X's (a female), with no SRY.

You can also learn more by reading about the Wolffian and Mullerian ducts.

http://en.wikipedia.org/wiki/Develop...ductive_system