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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. At least one of the spores develop into haploid female gametophytes, the megagametophytes. [1] The megaspore mother cell arises within the megasporangium tissue.
In gymnosperms and flowering plants, the megaspore is produced inside the nucellus of the ovule.During megasporogenesis, a diploid precursor cell, the megasporocyte or megaspore mother cell, undergoes meiosis to produce initially four haploid cells (the megaspores). [1]
This megasporocyte undergoes meiotic cell division to form four cells that are haploid. Three cells die and one that is most distant from the micropyle develops into the megaspore. This megaspore becomes larger and the nucleus of it undergoes mitosis three times until there are eight nuclei. These eight nuclei are then arranged into two groups ...
Figure 1. depicts the process of nucellar embryony. A) begins with megaspore formation. B) shows the nucellus and forming of cells, nucellar embryonic initial cells, from the nucellus tissue. These initial cells form, divide, and expand. C) The nucellar embryos are developed. If and when a zygote is present, the nucellar embryos supersede the ...
Location of ovules inside a Helleborus foetidus flower. In seed plants, the ovule is the structure that gives rise to and contains the female reproductive cells. It consists of three parts: the integument, forming its outer layer, the nucellus (or remnant of the megasporangium), and the female gametophyte (formed from a haploid megaspore) in its center.
Within each ovule, a megaspore develops by mitosis into a megagametophyte. An archegonium develops within the megagametophyte and produces an egg. The whole of the gametophytic generation remains within the protection of the sporophyte except for pollen grains (which have been reduced to just three cells contained within the microspore wall).
A megasporocyte inside a megasporangium or ovule undergoes meiosis, producing four megaspores. Only one is a functional megaspore whereas the others stay dysfunctional or degenerate. The megaspore undergoes several mitotic divisions to develop into a female gametophyte (for example the seven-cell/eight-nuclei embryo sac in flowering plants).
Only one of the four resulting megaspores survives. This megaspore undergoes three rounds of mitosis, resulting in seven cells with eight haploid nuclei (the central cell has two nuclei, called the polar nuclei). The lower end of the embryonic sac consists of the haploid egg cell positioned in the middle of two other haploid cells, called ...