Standard Article

Mammalian Sex Determination

  1. Elena J Tucker,
  2. Andrew H Sinclair

Published Online: 19 SEP 2013

DOI: 10.1002/9780470015902.a0024967



How to Cite

Tucker, E. J. and Sinclair, A. H. 2013. Mammalian Sex Determination. eLS. .

Author Information

  1. Royal Children's Hospital, Murdoch Childrens Research Institute, Melbourne, Australia

Publication History

  1. Published Online: 19 SEP 2013


Mammals, birds, reptiles, insects and even some corals all have two distinct forms – male and female. Cues for sexual development have undergone rapid evolution with some species relying on genetic cues and others on environmental. In mammals, sex development is governed by genetics and almost always involves heterogametic XY males and homogametic XX females. The Y chromosome contains a sex-determining gene that initiates a cascade of developmental signals down the male path, leading to the development of testes and subsequently the male-specific sex cords and genitalia. In the absence of the Y chromosome, development proceeds down the female path leading to ovaries and female genitalia. Mammalian sex determination involves a complex interplay of many genes, with antagonism between male and female pathways reinforcing fate. Despite the finely tuned process of sex determination, genetic aberrations can tip the balance, leading to sex reversal or intermediate sex development. Humans and mice with disruptions in key gonadal genes leading to atypical sex development have provided the majority of insights into the process of sex development, but much remains to be learned.

Key Concepts:

  • Mammals are sexually dimorphic.

  • Sex development has undergone rapid evolution.

  • Mammalian sex development is governed by complex genetic networks.

  • Study of humans and mice with atypical sex development have provided insights into the genetic pathways of sex development.

  • Massively parallel sequencing will accelerate future discoveries into the genetic basis of sex development.


  • mammalian sex development;
  • sex determination;
  • disorders of sex development;
  • gonadal development;
  • gonadal dysfunction