About the Authors

Youichirou Ninomiya

To whom correspondence should be addressed. E-mail: yo.ninomy@zoo.ox.ac.uk

Affiliation Mammalian Development Laboratory, Department of Zoology, University of Oxford, Oxford, United Kingdom

Shizuko Ichinose

Affiliation Instrumental Analysis Research Centre, Tokyo Medical and Dental University, Bunkyo, Tokyo, Japan

Competing Interests

The authors have declared that no competing interests exist.

Author Contributions

Conceived and designed the experiments: YN. Performed the experiments: YN SI. Analyzed the data: YN SI. Contributed reagents/materials/analysis tools: YN SI. Wrote the paper: YN.