Cover image
Cover Spiraling spheres in the foreground illustrate the sequence of mammalian preimplantation embryonic development (PED), from unfertilized egg, to zygote, two-cell, four-cell, eight-cell, morula, and finally to blastocyst embryo. A comparison of the gene regulatory networks underlying the PED of human, mouse, and cattle (depicted as constellations), suggests an evolutionary model for transcription factor binding site insertion and rewiring of gene regulatory networks by transposons. (Cover illustration by Shui He. [For details, see Xie et al., pp. 804–815.])
