Micropyle

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micropyle

[′mī·krə‚pīl]
(botany)
A minute opening in the integument at the tip of an ovule through which the pollen tube commonly enters; persists in the seed as an opening or a scar between the hilum and point of radicle.

Micropyle

 

(1) An opening in the membrane of the eggs of insects, arachnids, some mollusks, fishes, and a number of other animals, through which the spermatozoon penetrates. (2) An opening in the apex of the ovule in higher seed plants, through which the pollen tube penetrates during pollination. The micropyle is formed because the integuments surrounding the ovule are unattached.


Micropyle

 

the canal in the integument or integuments of a plant through which the ovule is penetrated in gymnosperms by pollen grains and in angiosperms by pollen tubes. The external opening of the micropyle may be observed on the surface of a mature seed in the form of a dark dot.

References in periodicals archive ?
Extracellular environments for the initiation of external fertilization and micropylar plug formation in a cottid species, Hemitripterus villosus (Pallas) (Scorpaeniformes) with internal insemination.
Aged seeds which have just started to germinate can be identified by a characteristic hole on the micropylar end which remains identifiable when the seed has been processed using side-striking techniques.
In Heteroptera, depending on the species, micropylar processes vary in number, shape, and size, and enable the gas exchange of the developing embryo.
After growing through nucellar tissue for three days, from one to several pollen tubes approach the micropylar end of the female gametophyte [ILLUSTRATION FOR FIGURE 4A OMITTED].
In the July 6 samples after double fertilization the zygote remained undivided which was located at the micropylar pole (Table 1).
In case of endosperm-limited germination, weakening of the micropylar endosperm surrounding the radicle tip appears to be required for radicle protrusion, and is likely to involve cell-wall hydrolysis by hydrolytic enzymes.
At 12 Days After Sowing (DAS) this face is completely swollen and micropylar pole is starting to break, probably due to water absorption by diaspore and embryonic development (Figure 3A).
Micropylar plate spade-shaped, gently tapering anteriorly, posterior margin truncate, central ridge about 1/2 length of the micropylar plate.
egg or egg cell: Middle of three haploid cells at the micropylar end of the embryo sac; when fertilized, it will form the zygote.
Fine structure of micropylar region during late oogenesis of eggs in the hagfish.
Except for the micropylar region, ridges extend all over the surface of the chorion.