Related Experiment Video
Updated: Jul 1, 2026

Dissection of Larval Zebrafish Gonadal Tissue
Published on: April 26, 2017
Amphibian sex determination and sex reversal
H Wallace1, G M Badawy, B M Wallace
1School of Biological Sciences, University of Birmingham, Edgbaston, UK. h.wallace@bham.ac.uk
Abstract:
Amphibians employ a genetic mechanism of sex determination, according to all available information on sex chromosomes or breeding tests. Sex reversal allows breeding tests to establish which sex is heterogametic and provides an indication of the mechanism of sex determination. Cases of spontaneous and experimental sex reversal (by temperature, hormones or surgery) are reviewed and illustrated by previously unpublished studies on crested newts. These newts respond conventionally to temperature and hormone treatment but provide anomalous results from breeding tests. It is suggested that both the evolution from temperature dependency to a genetic switch and from ZZ/ZW to XX/XY are superimposed on a generally uniform mechanism of sex determination in all vertebrates.
Related Concept Videos
Hybrid Zones
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...
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,...
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...
Development of the Sexual Organs in the Embryo and Fetus
Near the gonadal ridges, two duct systems are present: the mesonephric ducts (Wolffian ducts) and paramesonephric ducts (Müllerian ducts). These ducts form the basis for the male...

