Definitions
from The American Heritage® Dictionary of the English Language, 5th Edition.
- noun Any of the cells that give rise through mitosis to the oocytes and are found in the ovaries of vertebrates.
- noun A female reproductive structure in certain thallophytes and in oomycetes, usually a rounded cell or sac containing one or more oospheres.
from The Century Dictionary.
- noun In zoology: The primordial mother-cell which gives rise to the ovum and its follicle.
- noun One of the youngest ovarian cells, characterized by having in its nucleus the same number of chromosomes as in the nuclei of the somatic or body-cells. The oögonia, which eventually give rise to the primary oöcytes, are homologous in the oögenesis with the spermatogonia in the spermatogenesis of the male animal of the same species.
- noun In botany, the female sexual organ in certain cryptogamic plants.
from the GNU version of the Collaborative International Dictionary of English.
- noun (Bot.) A special cell in certain cryptogamous plants containing oöspheres, as in the rockweeds (Fucus), and the orders Vaucherieæ and Peronosporeæ.
from Wiktionary, Creative Commons Attribution/Share-Alike License.
- noun biology An
immature ovarian egg within a developingfetus
Etymologies
from The American Heritage® Dictionary of the English Language, 4th Edition
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Examples
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The female reproductive structure (oogonium) of a charophyte.
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The number of antheridia attached to a single oogonium shows very little tendency to definiteness, except in A. racemosa (Fig. 94).
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Oospores one or two in an oogonium; hy phse slender S.asteboprora. oospores several in an oogonium; hypbcB very stout » 8.
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After the growth of the oogonium has ceased and the protoplasm has become parietal in position, the outer walls thicken and the basal wall is formed, as already described.
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Mor - phologically sexual reproduction by oospores developed in typically globular oagouia, one or more from the entire protoplasm of each oogonium; antheridia on branches of androgynous or diclinous origin, very rarely on the oogonial branch, uniting with all, or with only a part of the oiigonia, or in several species wholly absent; when present, usually producing fertilization tubes which remain closed, at least in some species.
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In case of the androgynous species, the antheridial branches begin to appear soon after the oogonial ones (Fig. 21); but the antheridia have usually been formed and come into contact with the oogonium before the basal wall of the latter has appeared.
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The formation of these follows the same course as that above described for the polysporic oogonium, with certain necessary simplifications.
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The num - ber of these nuclei bears no relation to the number of oospheres to be formed, except as both are controlled by the amount of protoplasm in the oogonium.
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Antheridia clavate, one, or rarely more, on each oogonium, usually arising just below its basal wall, rarely of diclinous origin.
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B. Oddpore single, wholly filling the oogonium LeptoUgnia. oospores one or more, not wholly filling the odgonium Saprolbonia.
avivamagnolia commented on the word oogonium
~ Primitive differentiated female gamete which gives rise to oocytes. Singular of oogonia.
~ An immature ovum. It is a female gametogonium.
~ Oogonia are formed in large numbers by mitosis early in fetal life from primordial germ cells, which are present in the fetus between weeks 4 and 8. Oogonia are present in the fetus between weeks 5 and 30.
~ Oogonia are also the female reproductive structures in certain thallophytes, and are usually rounded cells or sacs containing one or more oospheres.
January 18, 2009