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 ?
Follicles generally thin walled (a stout capsule in secondarily syncarpous species); seeds flat, linear to ellipsoid or ovate, the testa glabrous or hairy with micropylar (sometimes rostrate) coma.
Follicles usually slender; seeds linear, testa glabrous, with micropylar coma.
of Prestonia, but splitting apart at maturity along suture); seeds mostly linear but broadly ovate in Parsonsia and Artia, testa glabrous, with micropylar (often rostrate) coma.
Fruit a pair of slender to sometimes very swollen, fusiform, ventrally dehiscent follicles (sometimes one by abortion: Raphionacme) with dry pericarp; seeds numerous, compressed, usually narrowly elliptical in outline, without winglike margin, with micropylar coma (extended around entire margin in Finlaysonia and Raphionacme nemibiana), endosperm thin.
Fruit a pair of slender to stout, fusiform, ventrally dehiscent follicles with dry pericarp; seeds numerous, compressed, more or less elliptical in outline, without winglike margin, with micropylar coma, endosperm thin.
Table I Micropylar nucellar structures in some families of Liliales
Table II Micropylar nucellar structures in commelinoid families
Dahlgren (1940) noted that the nucellus sometimes becomes destroyed more rapidly at the sides of the embryo sac than at the proximal and micropylar ends.
These somewhat loosely defined haustoria are not strictly comparable with the chalazal and micropylar endosperm haustoria found in many Asteridae, such as Lamiaceae (Rudall & Clark, 1992), where distinct well-defined endosperm chambers are formed, often containing a few large coenocytic nuclei which may wander around the periphery of the haustorium.