from The American Heritage® Dictionary of the English Language, 4th Edition
- n. A large nonmotile female gamete or egg cell, formed in an oogonium and ready for fertilization.
from Wiktionary, Creative Commons Attribution/Share-Alike License
- n. A large nonmotile egg cell formed in an oogonium and ready for fertilization
from the GNU version of the Collaborative International Dictionary of English
- n. An unfertilized, rounded mass of protoplasm, produced in an oögonium.
- n. An analogous mass of protoplasm in the ovule of a flowering plant; an embryonic vesicle.
from The Century Dictionary and Cyclopedia
- n. In cryptogams, the naked nucleated spherical or ovoid mass of protoplasm in the center of the oögonium, which after fertilization develops the oöspore.
from WordNet 3.0 Copyright 2006 by Princeton University. All rights reserved.
- n. a gamete; used especially of lower plants
The sexual generation is a small green thalloid structure called a prothallium, which bears antheridia and archegonia, each archegonium having a neck-canal and oosphere, which is fertilized just as in the moss.
Guided by the synergidae one male-cell passes into the oosphere with which it fuses, the two nuclei uniting, while the other fuses with the definitive nucleus, or, as it is also called, the endosperm nucleus.
After impregnation the fertilized oosphere immediately surrounds itself with a cell-wall and becomes the oospore which by a process of growth forms the embryo of the new plant.
Each protuberance bursts, and some of the spermatozoids come in contact with and are absorbed by the oosphere, which then secretes a cell-wall, and after a time germinates.
The pollen cells are formed from mother cells by a process of cell division and subsequent setting free of the daughter cells or pollen cells by rejuvenescence, which is distinctly comparable with that of the formation of the microspores of Lycopodiaceæ, etc. The subsequent behavior of the pollen cell, its division and its fertilization of the germinal vesicle or oosphere, leave no doubt as to its analogy with the microspore of vascular cryptogams.
The protoplasm in one of these protuberances arranges itself into a round mass -- the oosphere or female cell.
In Coleochæte, the male cell is a round spermatozoid, and the female cell an oosphere contained in the base of a cell which is elongated into an open and hair-like tube called the trichogyne.
Down this canal pass one or more antherozoids, which become absorbed into the oosphere, and this then secretes a wall, and from it grows the second or asexual generation.
Those which are of two kinds are, first, a generally aggressive and motile fertilizing or so-called "male cell," called in its typical form an _antherozoid_; and, second, a passive and motionless receptive or so-called "female cell," called an _oosphere_.
The spermatozoid coalesces with the oosphere, which secretes