The bipartite TAD organization of the X-inactivation center ensures opposing developmental regulation of Tsix and Xist by Van Bemmel, J, Galupa, R, Gard, C, Servant, N, Picard, C, Davies, J, Szempruch, A, Zhan, Y, Żylicz, J, Nora, E, Lameiras, S, De Wit, E, Gentien, D, Baulande, S, Giorgetti, L, Guttman, M, Hughes, J, Higgs, D, Gribnau, J, Heard, E