Large spore in heterosporous plants that germinates into a female gametophyte
Microscopic photo of spores (in red) of Selaginella. The large three spores at the top are megaspores whereas the numerous smaller red spores at the bottom are microspores.
Megaspores, also called macrospores, are a type of spore that is present in heterosporous plants. These plants have two spore types, megaspores and microspores. Generally speaking, the megaspore, or large spore, germinates into a female gametophyte, which produces egg cells. These are fertilized by sperm produced by the male gametophyte developing from the microspore. Heterosporous plants include seed plants (gymnosperms and flowering plants), water ferns (Salviniales), spikemosses (Selaginellaceae) and quillworts (Isoetaceae).
Megaspores, also called macrospores, are a type of spore that is present in heterosporous plants. These plants have two spore types, megaspores and microspores...
A megaspore mother cell, or megasporocyte, is a diploid cell in plants in which meiosis will occur, resulting in the production of four haploid megaspores...
the megasporangium), and the female gametophyte (formed from a haploid megaspore) in its center. The female gametophyte — specifically termed a megagametophyte...
the megaspore, which arises from megasporogenesis, develops into the embryo sac, which is where the female gamete is housed. These megaspores then develop...
generations. The spores of seed plants are produced internally, and the megaspores (formed within the ovules) and the microspores are involved in the formation...
megaspores are dispersed from sporangia either passively or by active ejection. Microspores produce microgametophytes which produce sperm. Megaspores...
female spore is considerably larger than a male spore, it is termed a megaspore. Azolla has microscopic male and female gametophytes that develop inside...
plants. The smaller of these, the microspore, is male and the larger megaspore is female. Heterospory evolved during the Devonian period from isospory...
cell division, producing four haploid megaspores. Only one of the four resulting megaspores survives. This megaspore undergoes three rounds of mitotic division...
are the male cells; they are borne in the stamens. The female cells, megaspores, divide to become the egg cell. They are contained in the ovule and enclosed...
size. Spores of two distinct sizes (heterospory or anisospory): larger megaspores and smaller microspores. When the two kinds of spore are produced in different...
apomixis in flowering plants: Nonrecurrent apomixis: In this type "the megaspore mother cell undergoes the usual meiotic divisions and a haploid embryo...
may be identical isospores or come in different sizes (microspores and megaspores), but strictly speaking, spores and sporophytes are neither male nor female...
mother cells within the anther give rise to haploid pollen grains, and megaspore mother cells in ovules that are contained within the ovary give rise to...
generating two different types of spores: male microspores and female megaspores. These spores develop on separate male and female sporophylls on separate...
as male (producing sperm or microspores) and female (producing ova or megaspores). In isogamous species, the gametes are similar or identical in form (isogametes)...
producing male and female gametophytes were of different sizes, the female megaspores tending to be larger, and fewer in number, than the male microspores....
they are heterosporous, having two spore types, microspores (male) and megaspores (female) that are typically produced in pollen cones or ovulate cones...
of two distinct sizes, larger megaspores and smaller microspores. Their reduced gametophytes developed from megaspores retained within the spore-producing...
Microspores are land plant spores that develop into male gametophytes, whereas megaspores develop into female gametophytes. The male gametophyte gives rise to sperm...
spores that contain the female gametophytes. Compare microsporangium. megaspore the larger of two kinds of spores produced by a heterosporous plant, giving...
Low magnification of an ultra-thin section (length = 0.5 mm) of a megaspore of Salvinia cucullata (intermediate lens micrograph taken with the ZEISS TEM...
pistillate flowers, diploid cells called megaspore mother cells undergo meiosis to produce haploid megaspores. In the anthers of the stamenate flowers...
8-12 mm in width. G. yimaensis also had pedicels 15-16 mm in length. The megaspore membrane of G. yimaensis and G. biloba are similar. However, it appears...
layering of cells in the apical meristem, pollen and megaspore features (including thin megaspore wall), short cambial initials, and lignin syringal groups...
occurs and a megaspore is produced as the first cell of the megagametophyte. As cell division takes place the nucleus of the megaspore thickens, and...
Figure 1. depicts the process of nucellar embryony. A) begins with megaspore formation. B) shows the nucellus and forming of cells, nucellar embryonic...
general appearance. The best way to identify them is by examining their megaspores under a microscope. Moreover, habitat, texture, spore size, and velum...
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