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– Morphology:
– The microspore has three different types of wall layers: perispore, exospore, and endospore.
– The perispore is the thickest layer, while the exospore and endospore are relatively equal in width.

– Seedless vascular plants:
– Heterosporous seedless vascular plants have modified leaves called microsporophylls bearing microsporangia.
– Each microsporocyte produces four microspores, which can develop into male gametophytes.
– Megaspores develop into female gametophytes, producing egg cells that develop into seeds.
Pollen cones or microstrobili develop in clusters up to 50 or more.
– Gymnosperms have microsporangia that develop in pairs toward the bases of scales.

– Angiosperms:
– The anther of a flowering plant develops four patches of tissue containing diploid microsporocyte cells.
– After meiosis, microspores undergo changes and develop into pollen grains.
– The generative cell forms inside the tube cell within the microspore.
– A double-layered wall develops around each microspore.
– These changes occur in sequence to form pollen grains.

– Embryogenesis:
Microspore embryogenesis is used to produce double haploid plants in biotechnology.
– Over 250 species of angiosperms respond to stressors like heat or starvation by selecting for microspore embryogenesis.
– Microspores can deviate towards embryogenesis in the anther and become star-like microspores.
Microspore embryogenesis pathway can lead to the production of haploid/double haploid plants or pollen-like structures.
– Double haploid technology accelerates the production of homozygous lines in one generation.

– See also:

Microspore (Wikipedia)

Microspores are land plant spores that develop into male gametophytes, whereas megaspores develop into female gametophytes. The male gametophyte gives rise to sperm cells, which are used for fertilization of an egg cell to form a zygote. Megaspores are structures that are part of the alternation of generations in many seedless vascular cryptogams, all gymnosperms and all angiosperms. Plants with heterosporous life cycles using microspores and megaspores arose independently in several plant groups during the Devonian period. Microspores are haploid, and are produced from diploid microsporocytes by meiosis.

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.
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