Sex Determination Animations




Sex Determination Animations (Howard Hughes Medical Institute)

From the 2001 Holiday Lectures — The Meaning of Sex: Genes and Gender

Evolution of the Y Chromosome (Howard Hughes Medical Institute)

How did the human Y chromosome become so small relative to its X counterpart? This animation depicts the 300-million-year odyssey of the sex chromosomes that began when the proto X and Y were an identical pair.


Gender Testing of Athletes

At times those responsible for conducting high-stakes athletic competitions like the Olympics have been greatly concerned with gender testing athletes. Learn why verifying a person's gender may be harder than you think.


Meiosis (Howard Hughes Medical Institute)

Meiosis, the form of cell division unique to egg and sperm production, sets the stage for sex determination by creating sperm that carry either an X or a Y sex chromosome. But what is it about the X or Y that determines sex?


MIX-1 (Howard Hughes Medical Institute)

This animation shows how MIX-1 facilitates both chromosome condensation and dosage compensation.


The Y Chromosome (Howard Hughes Medical Institute)

The Y chromosome has been likened to a hall of mirrors because its sequence contains many sections that appear to be palindromes. These palindromes provide a clue to some interesting events that may have occurred during the course of the chromosome's evolution.


How Is Sex Determined?
Most of the time, an embryo growing in the womb fully develops into either a male or a female with all the appropriate body parts and, many scientists believe, a mindset programmed according to its gender. What determines its gender -- in most cases -- are its sex chromosomes: two X chromosomes in the nucleus of its original egg cell and it will become a female; a Y and an X chromosome and it will become a male. But exactly what happens in the womb to make a boy or a girl? This interactive feature illustrates the astonishing changes that occur during the first 16 weeks of development.

Fertility Throughout Life
Remember that universally awkward moment around the sixth grade when your teacher inaugurated your reproductive life with an embarrassing sex education lecture? Your teacher clued you in to the main events of human reproductive biology, yet despite all that and everything you've learned since about the birds and the bees, you may still remain largely in the dark as to the complex nature of human fertility. Throughout our lives, from infancy to old age, our bodies undergo a dramatic set of transformations that enable us to reproduce when our bodies are most up to the task. In this interactive feature, explore the past, present, and future of your fertility as you may never have explored it before.

Sexual Reproduction