Early mouse development ♀ Pronucleus d Pronucleus Cleavage Zona A. Zygote B. 2 cell 1.5d C. 4 cell 2d nner cell mass Trophectoderm Blastocoel (ICM) vity Compaction Formation of blastocoel D. Morula 2.5d E. 3d F. Blastocyst 3.5d Primitive ectoderm Trophectoderm From endoderm Primitive Sedivy Uterus ectoderm Joyner Gene Targeting Uterus 1992 G. Implantation 4.5d H. Egg cylinder 6dEarly mouse development From Sedivy & Joyner “Gene Targeting” 1992