• DOI:10.1159/000358406
• Corpus ID: 3035039

Gonadal Asymmetry and Sex Determination in Birds

@article{Guioli2014GonadalAA,
  title={Gonadal Asymmetry and Sex Determination in Birds},
  author={Silvana Guioli and Sunil Nandi and Debiao Zhao and Jessica Burgess-Shannon and Robin Lovell-Badge and Michael Clinton},
  journal={Sexual Development},
  year={2014},
  volume={8},
  pages={227 - 242}
}

• S. Guioli, S. Nandi, +3 authors M. Clinton
• Published 27 February 2014
• Biology
• Sexual Development

Although vertebrates display a superficial bilateral symmetry, most internal organs develop and locate with a consistent left:right asymmetry. There is still considerable debate as to when this process actually begins, but it seems that, at least for some species, the initial steps occur at a very early stage of development. In recent years, a number of model systems, including the chick embryo, have been utilised to increase our understanding of the molecular basis of this complex developmental process. While the basic elements of asymmetry are clearly conserved in chick development, the chick embryo also exhibits an additional unusual asymmetry in terms of the development of the gonads. In the female chick embryo, only 1 gonad and accessory structures fully develop, with the result that the adult hen has only 1 ovary and a single oviduct - both on the left side. With a small number of exceptions, this is a consistent feature of avian development. Here, we describe the morphological development and molecular basis of this unusual asymmetry, consider the implications for avian sex determination, and discuss the possible biological reasons why many birds have adopted a single-ovary system.