There were errors published in Development141, 101-111.

Boris Joffe and Irina Solovei have been added to the author list for their contribution to the design of 3D-FISH experiments and data analysis. The middle initial of Vladimir U. Emelianov has been corrected. These changes have been incorporated into the revised author list and affiliations, as shown above, and are accounted in the revised Acknowledgements and Author contributions sections, as shown below.

A.N.M. designed and undertook experiments, analysed results and helped write the paper; M.R.G. and J.L.Y. undertook experiments, analysed results and helped to write the paper; V.U.E., A.A.S., T.Y.S. and J.A.S. undertook experiments and analysed results; K.P. analysed results and helped to write the paper; B.J. and I.S. designed experiments and performed data analysis; P.C. provided crucial reagents and helped to write the paper; V.A.B. and M.Y.F. designed the experiments, analysed results and wrote the paper.

In addition, In Fig. 3A the white and grey bars were incorrectly labelled in the key. The corrected Fig. 3A appears below.

The authors apologise to readers for these mistakes.

We greatly appreciate the invaluable help and support of Prof. T. Cremer (Ludwig-Maximillians University Munich, Germany) in establishing 3D-FISH technology and data analysis.