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Pollen itself is not the male gamete. [4] It is a gametophyte, something that could be considered an entire organism, which then produces the male gamete.Each pollen grain contains vegetative (non-reproductive) cells (only a single cell in most flowering plants but several in other seed plants) and a generative (reproductive) cell.
Tapetum is important for the nutrition and development of pollen grains and a source of precursors for the pollen coat. [1] The cells are usually bigger and normally have more than one nucleus per cell. As the sporogenous cells undergo mitosis, the nuclei of tapetal cells also divide. Sometimes, this mitosis is abnormal, which is why many cells ...
The male reproductive organ of the flower, the stamen, produces pollen. The opening of anthers makes pollen available for subsequent pollination (transfer of pollen grains to the pistil, the female reproductive organ). Each pollen grain contains a vegetative cell, and a generative cell that divides to form two sperm cells.
Spore mother cells in the microsporangia divide by meiosis to form haploid microspores that develop further by two mitotic divisions into immature male gametophytes (pollen grains). The four resulting cells consist of a large tube cell that forms the pollen tube, a generative cell that will produce two sperm by mitosis, and two prothallial ...
SEM image of pollen grains. Sporopollenin is a biological polymer found as a major component of the tough outer (exine) walls of plant spores and pollen grains. It is chemically very stable (one of the most inert among biopolymers) [1] and is usually well preserved in soils and sediments.
Alongside the tapetosomes (clusters of oil and proteins produced by the endoplasmic reticulum), elaioplasts are frequently found in the tapetum of angiosperm anthers, where their products, oil from the plastid and protein from the tapetosome, are used to form the pollen coat of developing grains. [1]
The pollen is carried to the pistil of another flower, by wind or animal pollinators, and deposited on the stigma. As the pollen grain germinates, the tube cell produces the pollen tube, which elongates and extends down the long style of the carpel and into the ovary, where its sperm cells are released in the megagametophyte.
An endosperm is formed after the two sperm nuclei inside a pollen grain reach the interior of a female gametophyte or megagametophyte, also called the embryonic sac.One sperm nucleus fertilizes the egg cell, forming a zygote, while the other sperm nucleus usually fuses with the binucleate central cell, forming a primary endosperm cell (its nucleus is often called the triple fusion nucleus).