Proembryo

Pro‐em″bry‐o (?), n. [Pref. pro- + embryo.] (Bot.) (a) The series of cells formed in the ovule of a flowering plant after fertilization, but before the formation of the embryo. (b) The primary growth from the spore in certain cryptogamous plants; as, the proembryo, or protonema, of mosses.