amnio-

The amnion.

Greek amnion, caul, a diminutive of amnos, lamb.

The amnion is the innermost membrane that encloses the embryo of a mammal, bird, or reptile, for which the adjective is amniotic. Amniocentesis is the process of sampling that fluid for analysis. Related medical terms include amniotomy (Greek ‑tomia, cutting), the artificial rupture of the amnion immediately before birth, and amnionitis, an inflammation of the amnion that may be caused by premature rupture of the membrane.