Pollen Tube


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pollen tube

[′päl·ən ‚tüb]
(botany)
The tube produced by the wall of a pollen grain which enters the embryo sac and provides a passage through which the male nuclei reach the female nuclei.
McGraw-Hill Dictionary of Scientific & Technical Terms, 6E, Copyright © 2003 by The McGraw-Hill Companies, Inc.
The following article is from The Great Soviet Encyclopedia (1979). It might be outdated or ideologically biased.

Pollen Tube

 

a tubular outgrowth of a pollen grain that forms in seed plants after pollination. In its early development, it consists of a protuberance of the protoplast of the pollen grain. Covered with an internal membrane (intine), the tube emerges through a slender area of the pollen grain’s external membrane. In gymnospermous plants the pollen tube is formed in the pollen sac of the ovule; here it is embedded in the tissue of the nucellus. The pollen tube serves only as a haustorium (sucker) that receives nutrient matter (for example, in Cycadophyta and Ginkgo), or it ensures conduction of the male gametes to the female prothallium—the primary endosperm (in conifers and Gneticae).

In angiosperms the pollen grains form pollen tubes on the stigma of the pistil singly (in most plants) or in groups (in Malvaceae and Cucurbitaceae). The pollen tube, growing at its apex, emerges between the papillae of the stigma and then grows into the style and along the cells that line the stylar canal. If there is no canal, the tube grows between the cells of the stylar tissue, destroying the intercellular matter and, sometimes, the cells.

The pollen tube penetrates the ovule through the micropyle (porogamy) or, less frequently, through the chalaza (chalazogamy; in many Amentaceae) or laterally through the integument (mesogamy). In the female gametophyte—the embryo sac—the pollen tube usually enters between the egg cell and the synergid, or, upon destroying one of the synergids, it opens and releases the spermatozoids, after which double fertilization is possible.

A. N. SLADKOV

The Great Soviet Encyclopedia, 3rd Edition (1970-1979). © 2010 The Gale Group, Inc. All rights reserved.
References in periodicals archive ?
As for other species, cycad pollen germination and pollen tube growth is influenced by several environmental factors, particularly temperature and moisture (relative humidity), (Stanley and Linskens, 1974).
Wullems, "Regulation of flavonol biosynthesis during anther and pistil development, and during pollen tube growth in Solanum tuberosum," The Plant Journal, vol.
The data obtained support the hypothesis that stigma excision can remove glycoproteins, and that pollen is able to germinate and start the pollen tube growth in the style tissues.
They further indicated that the high requirement of calcium and low calcium content of most pollen may conspire to give calcium a governing role in the growth of pollen tubes both in vitro and in situ.
The present work aims to come out with a natural material of plant origin to be used as an assistant for the pollen to accomplish its mission in fertilization by improving pollen tube morphology.
Pollen tube growth behavior was studied using fluorescent microscope.
* clarify the beneficial effect of maternal sporophytic tissue and ovules to trigger pollen tube growth,
Morphological descriptions of pollen growth and development in 'Ataulfo' were not found in the literature, nor were references to pollen tube growth rate and velocity in mango.
A very low percentage and only the largest pollen germinated (growing of a pollen tube) on an Agar plate, indicating that this must be a hybrid.
As a further test of compatibility, pollen tube germination on the stigma of self pollinated and cross pollinated flowers was analyzed.
Following pollination, the pollen grain germinates and produces a pollen tube, which delivers the sperm directly to the archegonium.