amniotic cavity

https://doi.org/10.1351/goldbook.10370

Fluid-filled space that surrounds the developing embryo of a mammal, bird, or reptile, bounded by the amniotic sac.

Source:
PAC, 2016, 88, 713. (Glossary of terms used in developmental and reproductive toxicology (IUPAC Recommendations 2016)) on page 720 [Terms] [Paper]