Crossword clues for antheridium
The Collaborative International Dictionary
Antheridium \An`ther*id"i*um\, n.; pl. Antheridia. [Anther + ? (a Gr. diminutive ending).] (Bot.) The male reproductive apparatus in the lower plants, consisting of a cell or other cavity in which spermatozoids are produced; -- called also spermary. -- An`ther*id"i*al, a.
Wiktionary
n. (context botany English) An organ producing male gametes called antherozoids, found in bryophytes.
WordNet
n. the male sex organ of spore-producing plants; produces antherozoids; equivalent to the anther in flowers
[also: antheridia (pl), andtheridia (pl)]
Wikipedia
An antheridium or antherida (plural: antheridia) is a haploid structure or organ producing and containing male gametes (called antherozoids or sperm). It is present in the gametophyte phase of cryptogams like bryophytes and ferns, and also in the primitive vascular psilotophytes. Many algae and some fungi, for example ascomycetes and water moulds, also have antheridia during their reproductive stages.
An antheridium typically consists of sterile cells and spermatogenous tissue. The sterile cells may form a central support structure or surround the spermatogenous tissue as a protective jacket. The spermatogenous cells give rise to spermatids via mitotic cell division. In bryophytes, the antheridium is borne on an antheridiophore, a stalk-like structure that carries the antheridium at its apex.
In many gymnosperms and all angiosperms, the male gametophytes have been reduced to pollen grains and their antheridia have been reduced to a single generative cell within the pollen grain. During pollination, this generative cell divides and gives rise to two sperm cells.
The female counterpart to the antheridium is the archegonium.
Usage examples of "antheridium".
Each antheridium or archegonium arises from a single cell, and while the mature structure is similar in the two groups, the development presents differences in liverworts and mosses.
Without entering into details it may be mentioned that in the mosses it proceeds both in the archegonium and antheridium by the segmentation of an apical cell, while this is not the case in the liverworts.
When mature the antheridium opens on being moistened and the spermatozoids become free in the water by the dissolution of the mucilaginous cell-walls enclosing them.
The small thallus bears the antheridia and archegonia, each of which is surrounded by a tubular involucre, on the upper surface of distinct individuals.
Their general similarity to the mature antheridia and archegonia of liverworts and the main difference in their development have been referred to.
The stalked globular antheridia are exceptional in being formed endogenously, and are situated in groups in special intercellular spaces.