Conceptus (
Latin:
conceptio, meaning 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,
chorion (gestational sac), and
yolk sac.