pollen tube

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Fig. 255 Pollen tube . Section of grain, showing tube.

pollen tube

a slender structure produced from a POLLEN GRAIN after POLLINATION. The tube protrudes from a pore in the EXINE and grows down through the stigma, style and ovary of the CARPEL, entering the ovule usually by the micropyle. See Fig. 255 . Within the tube, the haploid generative nucleus divides by MITOSIS to give two MALE GAMETE NUCLEI which have an important function in the double FERTILIZATION process of higher plants (see EMBRYO SAC). The growth of the tube appears to be controlled by the tube nucleus and there is some evidence that the tube shows negative AEROTROPISM. The stimulus for the original germination of the pollen grain comes from a sugary fluid secreted by the stigma. Sometimes, however, germination is prevented by SELF-INCOMPATIBILITY factors in the stigma cells and pollen grain, which prevent self-pollination in some plants.
References in periodicals archive ?
Differences in vitro pollen germination and pollen tube growth of cotton cultivars in response to high temperature.
The incompatible pollen tube growth is inhibited at the stigmatic surface (REGO et al.
The smallest pollen tubes were observed in the M1 medium, and most of the genotypes produced no germinated pollen in this medium.
Pollen was considered to have germinated if the pollen tube was twice as long as the diameter of the pollen grain (Nyomora et al.
Sometimes, unilateral incompatibility results when pollen tube growth is
pollen tubes in all treatments, the best treatment was one point of 100ppm Date Palm Pollen extract solution+ 2ml of the culture medium, percentage of normal type according to this treatment was 86% compared to control 63.
Polyethylene glycol improves the in vitro growth of Brassica pollen tubes without loss in germination.
Large number of pollen tubes was noticed to grow through style during third flash when 3 h aged stigmas were pollinated with 3 h aged pollens.
The students themselves prepare the growth medium and the plates, dissect and manipulate the flower organs, and see how the pollen tubes penetrate the female pistil.
Staining pollen tubes in the styles of cereals with cotton blue: fixation by ethanol-lactic acid for an enhanced differentiation.
Following pollination, the pollen grain germinates and produces a pollen tube, which delivers the sperm directly to the archegonium.
Martin FW (1959) Staining and observing pollen tubes in the style by means of fluorescence.