This entire structure is the corianic cavity and this outside portion is the coriane. This extension is what becomes our placenta. This structure here that connects the placenta, the corian, to the growing embryo is the embryonic stock. And this will eventually develop into the embryonic tube, that embryonic section, the embryonic cord that connects that placenta to that developing fetus. And this is the amniotic cavity that contains that houses that growing fetus. So this is the process that we call gastrilation.