Sex determination in the teleost medaka, Oryzias latipes
Related Experiment Video
Updated: Aug 14, 2026

Sperm Collection and Computer-Assisted Sperm Analysis in the Teleost Model Japanese Medaka (Oryzias latipes)
Published on: October 6, 2022
1PRESTO, Japan Science and Technology Corporation, Laboratory of Reproductive Biology, National Institute for Basic Biology, Okazaki 444-8585, Japan. matsuda@nibb.ac.jp
Abstract:
Although the sex of most animals is determined by genetic information, sex-determining genes had been identified only in mammals, several flies, and the worm Caenorhabditis elegans until the recent discovery of DMY (DM-domain gene on the Y chromosome) in the sex-determining region on the Y chromosome of the teleost fish medaka, Oryzias latipes. Functional and expression analyses of DMY have shown it to be the master gene for male sex determination in the medaka. The only sex-determining genes found so far in vertebrates are Sry and DMY. Therefore, the medaka is expected to become a good experimental animal for investigating the precise mechanisms involved in primary sex determination in nonmammalian vertebrates. This article reviews the origin of DMY and the sexual development of gonads in the medaka. The putative functions of DMY are also discussed.
Related Concept Videos
The Ratio of X Chromosome to Autosomes
Normal male Drosophila has a ratio of one X chromosome to two sets of autosomes. In contrast, normal female Drosophila...
Dosage Compensation
In addition to sexual development, the X chromosome has genes involved in autosomal functions such as brain development and the immune system. Therefore, males and females with distinct numbers of X chromosomes will have...
The Y Chromosome Determines Maleness
Evolution
Around 300 million years ago, the two sex chromosomes diverged from two identical autosomal chromosomes. Over time, the Y chromosome has lost most of its genes, shrinking in size. Today,...
Background and Environment Affect Phenotype
An example of how genetic background affects phenotype can be seen in horses. The Extension gene in horses is responsible for their coat color. A wild-type gene (EE) produces black pigment in the coat, while a mutant gene (ee) produces red pigment. A...
Osmoregulation in Fishes
Understanding Species and Reproductive Barriers

