from The American Heritage® Dictionary of the English Language, 4th Edition
- n. Botany The smaller of two types of spores that give rise to a male gametophyte.
from Wiktionary, Creative Commons Attribution/Share-Alike License
- n. A small spore.
from the GNU version of the Collaborative International Dictionary of English
- n. One of the exceedingly minute spores found in certain flowerless plants, as Selaginella and Isoetes, which bear two kinds of spores, one very much smaller than the other. Cf. macrospore.
from The Century Dictionary and Cyclopedia
- n. In botany, an asexually produced spore of small size as compared with others produced by the same species: the homologue of the pollen-grain of phanerogams.
- n. In zoology, one of the spore-like elements, of exceedingly minute size, but very numerous, produced through the encystment and subsequent subdivision of many monads.
from WordNet 3.0 Copyright 2006 by Princeton University. All rights reserved.
- n. smaller of the two types of spore produced in heterosporous plants; develops in the pollen sac into a male gametophyte
Sorry, no etymologies found.
The first division is the microspore may be observed readily merely by using a squash technique.
Each Dt element must have been activated in the microspore nucleus or not later than the generative nucleus produced by division of the microspore nucleus.
This could be accomplished readily by observing the first mitotic division in the microspore.
This cycle, initially detected at the first mitosis in a microspore, could now be followed in subsequent mitoses.
Examination of the first mitotic division in the microspore revealed a strange behavior of the single broken end that had entered
The pollen cells are formed from mother cells by a process of cell division and subsequent setting free of the daughter cells or pollen cells by rejuvenescence, which is distinctly comparable with that of the formation of the microspores of Lycopodiaceæ, etc. The subsequent behavior of the pollen cell, its division and its fertilization of the germinal vesicle or oosphere, leave no doubt as to its analogy with the microspore of vascular cryptogams.
The macrospore or embryo-sac produces a prothallium called the endosperm, in which archegonia or corpuscula are formed; and lastly, in typical dicotyledons it is only lately that any trace of a prothallium from the microspore or pollen cell has been discovered, while the macrospore or embryo-sac produces only two or three prothallium cells, known as antipodal cells, and two or three oospheres, known as germinal vesicles.
_D_, a single ripe pollen spore (microspore), showing the vegetative cell
Germination of the microspore begins before it leaves the pollen-sac.
The essence of morphology (in the better and more precise sense) is descent; thus we say that a pollen-grain is morphologically a microspore.
Wordnik is becoming a not-for-profit! Read our announcement here.