conceptus n : 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 [syn: embryo, fertilized egg]

English

Etymology

Derived from the Latin concipere

Noun

1. The fetus or embryo, including all the surrounding tissues protecting and nourishing it during pregnancy.

References

American Heritage Dictionary of the English Language: Fourth Edition.

Conceptus (latin is conceptio, derivatives of zygote) denotes the embryo and its adnexa (appendages or adjunct parts) or associated membranes (i.e. the products of conception) The conceptus includes all structures that develop from the zygote, both embryonic and extraembryonic. It includes the embryo as well as the embryonic part of the placenta and its associated membranes - amnion, chorionic (gestational sac), and yolk sac.