Embryo Research -- ethics -- United States -- Guideline : The National Academies' guidelines for human embryonic stem cell research / Human Embryonic Stem Cell Research Advisory Committee, Board on Life Sciences, Division on Earth and Life Studies, Board on Health Sciences Policy, Institute of Medicine, National Research Council and Institute of Medicine of the National Academies
Experimentation on, or using the organs or tissues from, a human or other mammalian conceptus during the prenatal stage of development that is characterized by rapid morphological changes and the differentiation of basic structures. In humans, this includes the period from the time of fertilization to the end of the eighth week after fertilization
