One reference work says: “If one defines the embryo as the structure destined to become the baby, its earliest rudiments do not form until about two weeks after the sperm meets the egg. ”
Ühes teatmeteoses öeldakse: „Kui defineerida embrüot kui rakukobarat, millest peab arenema laps, siis selle varaseimad elundite alged hakkavad moodustuma alles kaks nädalat pärast seemneraku kohtumist munarakuga. ”