oecium

from The Century Dictionary.

• noun One of the bud-like cells or cysts of some polyzoans, as the marine gymnolæmatous forms of the order, which are specially formed to receive the ova, and in which the ova are fecundated; the kind of ovicell or oöcyst which a moss-animalcule may have.

from the GNU version of the Collaborative International Dictionary of English.

• noun (Zoöl.) One of the special zooids, or cells, of Bryozoa, destined to receive and develop ova; an ovicell. See bryozoa.