Megaspore mother cell
Encyclopedia
A megaspore mother cell is a diploid
cell in which meiosis
will occur, resulting in the production of four megaspore
s. This megasporcyte is formed from two distinct processes – megasporogenesis and megagametogenesis.
Within each sporangium
, meiosis of a megaspore mother cell produces four haploid megaspores. In gymnosperms and angiosperms, only one of these four megaspores is functional and the other three soon degenerate. The megaspore that remains divides mitotically
and develops into the female gametophyte, which eventually produces eggs
.
Ploidy
Ploidy is the number of sets of chromosomes in a biological cell.Human sex cells have one complete set of chromosomes from the male or female parent. Sex cells, also called gametes, combine to produce somatic cells. Somatic cells, therefore, have twice as many chromosomes. The haploid number is...
cell in which meiosis
Meiosis
Meiosis is a special type of cell division necessary for sexual reproduction. The cells produced by meiosis are gametes or spores. The animals' gametes are called sperm and egg cells....
will occur, resulting in the production of four megaspore
Megaspore
Megaspores, also called macrospores, are a type of spore that is present in heterosporous plants. These types of plants have two spore types, megaspores and microspores. Generally speaking, the megaspore, or large spore, germinates into a female gametophyte, which is fertilized by sperm produced...
s. This megasporcyte is formed from two distinct processes – megasporogenesis and megagametogenesis.
Within each sporangium
Sporangium
A sporangium is an enclosure in which spores are formed. It can be composed of a single cell or can be multicellular. All plants, fungi, and many other lineages form sporangia at some point in their life cycle...
, meiosis of a megaspore mother cell produces four haploid megaspores. In gymnosperms and angiosperms, only one of these four megaspores is functional and the other three soon degenerate. The megaspore that remains divides mitotically
Mitosis
Mitosis is the process by which a eukaryotic cell separates the chromosomes in its cell nucleus into two identical sets, in two separate nuclei. It is generally followed immediately by cytokinesis, which divides the nuclei, cytoplasm, organelles and cell membrane into two cells containing roughly...
and develops into the female gametophyte, which eventually produces eggs
Egg (biology)
An egg is an organic vessel in which an embryo first begins to develop. In most birds, reptiles, insects, molluscs, fish, and monotremes, an egg is the zygote, resulting from fertilization of the ovum, which is expelled from the body and permitted to develop outside the body until the developing...
.