title: Pushing the limit.
authors: Gretchen
authors: G
authors: Vogel
mesh_terms: D000818:Animals; D002454:Cell Differentiation; D046149:Embryo Culture Techniques; D010064:Embryo Implantation; D033041:Embryo Research / Q000941:ethics*; D004622:Embryo, Mammalian / Q000166:cytology*; D047108:Embryonic Development; D005260:Female; D005307:Fertilization in Vitro; D006801:Humans; D051379:Mice; D010920:Placenta; D011247:Pregnancy