What is "proembryo"

Proembryo \Pro*em"bry*o\, n. [Pref. pro- + embryo. ] (Bot.)

1. The series of cells formed in the ovule of a flowering plant after fertilization, but before the formation of the embryo.

2. The primary growth from the spore in certain cryptogamous plants; as, the proembryo, or protonema, of mosses.

n. 1 (context botany English) A cluster of cells in the ovule of a fertilized flowering plant that has not yet formed into an embryo 2 (context botany English) The protonema of mosses

Proembryo, or pro-embryo, is a botanical term that has been used for centuries, to denote the series of cells that are formed after fertilization within the ovule of a flowering plant, before formation of the embryo.

More recently, this same term has been given a more extensive meaning, with reference to human egg cells ( ova) that have been fertilized but not yet implanted into a uterus. This more recent meaning is synonymous with "preembryo" or "pre-embryo," and corresponds to stages with more accepted terms zygote and blastocyst.