Generally speaking, the megaspore, or large spore, germinates into a female gametophyte, which produces egg cells.
22.
During this time, the megaspore mother cell divides by meiosis to form four haploid cells, three of which degenerate.
23.
For example, in flowering plants, microspores ultimately produce microgametes ( sperm ) and megaspores ultimately produce megagametes ( eggs ).
24.
Distinctive characteristics of this species include brown-spotted sporangial walls and megaspores with highly reticulate ridges, producing a spiny effect.
25.
In organisms that are heterosporous, two types of spores occur : Microsporangia produce male microspores, and megasporangia produce female megaspores.
26.
In heterosporous vascular plants ( plants that produce both microspores and megaspores ), the gametophyte develops endosporically, within the spore wall.
27.
The megagametophyte develops within the megaspore of extant seedless vascular plants and within the megasporangium in a cone or flower in seed plants.
28.
"' Microspores "'are land plant spores that develop into male gametophytes, whereas megaspores develop into female gametophytes.
29.
Therefore, each pattern gives rise to a single functional megaspore which contains one, two, or four meiotic nuclei, respectively.
30.
In gymnosperms and most flowering plants, only one of the four megaspores is functional at maturity, and the other three soon degenerate.
