EMBRYO By N., Pam M.S. - April 7, 2013 A stage in the development of an animal between cleavage of a fertilised egg and birthor hatching. In humans it is called a foetus after 8 weeks. EMBRYO: "The embryo in the egg hatched to become a fluffy yellow chick." Related Psychology Terms MORULA FETAL MONITORING FETAL DISTRESS GESTATION ZOOMORPHISM GESTATIONAL AGE FETAL ACTIVITY ANIMAL BEHAVIOR PRIMARY CIRCULAR REACTION BEHAVIORAL EMBRYOLOGY Cite this page: N., Pam M.S., "EMBRYO," in PsychologyDictionary.org, April 7, 2013, https://psychologydictionary.org/embryo/ (accessed June 2, 2020).