UCSB Science Line
Sponge Spicules Nerve Cells Galaxy Abalone Shell Nickel Succinate X-ray Lens Lupine
UCSB Science Line
Home
How it Works
Ask a Question
Search Topics
Webcasts
Our Scientists
Science Links
Contact Information
how does a boy/girl get different sex organs than each other
Answer 1:

In humans, sex determination actually happens a kind of late in embryonic development - in fact, all early embryos begin making the sex

organs for both sexes and then in response to hormones, one set will regress while one is retained. The hormone levels are related to whether there is the presence of a Y chromosome (male). Current research is focused on what genes on the Y chromosome actually direct the expression of specific genes that then drive the hormonal levels.

In other animals, especially a lot of reptiles, other, environmental factors can drive sex determination - a particular temperature of egg incubation might favor one sex over the other. Or, if the general population has relatively few females, there is a tendency for new clutches of eggs to be largely female. Although we know about the hormones, we don't understand the triggers of this very well.

So keep asking this question - maybe you will be the one to figure out in the near future!


Answer 2:

This depends on the animal we are considering, bu there is how it works in humans:

Early in the embryo, a gene on the Y chromosome, if the fetus has a Y chromosome, floods the body with testosterone. This triggers the development of male sex organs. If the gene isn't there, as is the case if the fetus has no Y chromosome, then it develops into a female by default.

As I say, other animals do it differently.



Click Here to return to the search form.

University of California, Santa Barbara Materials Research Laboratory National Science Foundation
This program is co-sponsored by the National Science Foundation and UCSB School-University Partnerships
Copyright © 2015 The Regents of the University of California,
All Rights Reserved.
UCSB Terms of Use