conceptus conceptus /kɒnˈsɛptəs/

noun

1. An animal organism in the early stages of growth and differentiation that in higher forms merge into fetal stages but in lower forms terminate in commencement of larval life  ( conceptus , embryo , fertilized egg , fertilised egg [British] )
   an animal organism in the early stages of growth and differentiation that in higher forms merge into fetal stages but in lower forms terminate in commencement of larval life
    The embryo implants in the uterus a few days after fertilization
   The embryo implants in the uterus a few days after fertilization