microspore

mi·cro·spore

M0277300 (mī′krə-spôr′)n. Botany A spore that gives rise to a male gametophyte and is smaller than a megaspore.

mi′cro·spo′ric, mi′cro·spo′rous (mī′krə-spôr′əs, mī-krŏs′pər-əs) adj.

microspore

(ˈmaɪkrəʊˌspɔː) n1. (Botany) the smaller of two types of spore produced by some spore-bearing plants, which develops into the male gametophyte. Compare megaspore¹2. (Botany) the pollen grain of seed plants ˌmicroˈsporic, ˌmicroˈsporous adj

mi•cro•spore

(ˈmaɪ krəˌspɔr, -ˌspoʊr)

n. the smaller of the two kinds of spores characteristically produced by seed plants and some fern allies, developing into a male gametophyte. Compare megaspore (def. 1). [1855–60] mi`cro•spor′ic (-ˈspɔr ɪk, -ˈspɒr-) mi`cro•spor′ous (-krəˈspɔr əs, -ˈspoʊr-, -ˈkrɒs pər əs) adj.

Thesaurus

Noun

microspore - smaller of the two types of spore produced in heterosporous plants; develops in the pollen sac into a male gametophytespore - a small usually single-celled asexual reproductive body produced by many nonflowering plants and fungi and some bacteria and protozoans and that are capable of developing into a new individual without sexual fusion; "a sexual spore is formed after the fusion of gametes"

Microspore

enUK

microspore

[′mī·krə‚spȯr] (botany) The smaller spore of heterosporous plants; gives rise to the male gametophyte.

Microspore

a small spore of heterosporous Pteridophyta (Selaginella, Isoetes, Salvinia, and other water ferns) and seed plants. Microspores are usually formed in large numbers in special organs, the microsporangia, as a result of meiosis of arche-spores. Consequently, microspores are haploid. The microspore is covered with a thin inner membrane (inline) and a thicker outer membrane (exine). When the microspore of a pteridophyte sprouts (usually in the microsporangium), it forms a greatly reduced male prothallium with sex organs, the antheridia. The sprouted microspores (prothallia) are transported by water, wind, or other agents, to the female prothallia, where the spermatozoids, freed from the antheridia, penetrate the archegonia for fertilization.

In seed plants the pollen grain, which is homologous to the male prothallium, arises from the microspore in the microsporangium. In gymnosperms the pollen grain consists of several vegetative cells and one antheridial cell and forms the male gametes (in sago palms and ginkgoes there are flagellate spermatozoids; the rest of the gymnosperms have nonmotile spermatozoids). Angiosperms have the most reduced male prothallia, consisting of one vegetative and one generative cell. After the pollen falls on the stigma of the pistil, the vegetative cell becomes extended into the pollen tube and the generative cell divides, forming two spermatozoids, of which one merges with the egg cell and the other merges with the secondary nucleus of the embryo sac.

WORKS

Komarnitskii, N. A., L. V. Kudriashov, and A. A. Uranov. Sistematika rastenii. Moscow, 1962.

L. V. KUDRIASHOV

microspore

mi·cro·spore

microspore

mi•cro•spore

Microspore

microspore

Microspore

WORKS

microspore

microspore

microspore

Words related to microspore

noun smaller of the two types of spore produced in heterosporous plants

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