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.
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.
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?
This animation shows how MIX-1 facilitates both chromosome condensation and dosage compensation.
A demonstration by Dr. Meyer showing how a balance of molecular elements trigger genetic pathways that determine the sex of a C. elegans worm.
A demonstration by Dr. Barbara Meyer of how a branched genetic pathway can be affected by mutations in different parts of the pathway.
Time-lapse microscopy showing cell division from 1 to 2 to 4 cell stages in C. elegans with fluorescent chromosomes.
Video of the fertilization of the C. elegans oocyte, the fusion of the egg and sperm nuclei, and the egg laying.
Video microscopy of mating between a male and a hermaphrodite C. elegans roundworm.
Video closeup of the C. elegans sperm that moves like an amoeba.
What does a stack of fruits and vegetables have to do with the theoretical advantages of sexual reproduction? Find out in this demonstration with student audience members and Dr. David Page.
Video microscopy demonstrating how sperm from an infertile male can be injected into a female egg.
A brief interview with Dr. Meyer.
A brief interview with Dr. Page.
Video microscopy of sperm motility in an average human male and an infertile male.
Four talks focus on sex determination—the molecular and genetic mechanisms that determine whether an organism will be male, female or a hermaphrodite.
Is it a boy or a girl? Dr. David Page looks at how we define male and female and summarizes the development of human sex characteristics.
Dr. Barbara Meyer explains the value of studying model organisms and introduces the nematode C. elegans.
Having too many chromosomes can lead to too much gene expression. Dr. Meyer explains how the gene that controls dosage compensation in C. elegans works.
Dr. Page explains how successive inversions and deletions of the Y chromosome during mammalian evolution have reduced it to its present form—small and sparsely populated with genes.
Answer the questions in this online quiz to test your knowledge of what determines the sex of a human, a fruit fly, and a snapping turtle.
Learn why verifying a person's gender may be harder than you think.
A text transcript of the 2001 Holiday Lectures on Science, The Meaning of Sex: Genes and Gender.
A chapter list to accompany the DVD.
A jigsaw format activity to explore the sex determination mechanisms of seven organisms.