ApertureAperture has several different meanings in biology, all of which are specific biologically functional openings.
In optics, it is a restriction of the diameter of a light path; without the aperture in mammalian and reptilian eyes, vision as we know it would not be possible.
An aperture is also an opening in the shell of a gastropod, like a snail or a conch, through which its body emerges. This elliptical or oval opening is usually closable by an operculum, and leads to a space which may take different shapes. This aperture has three walls: parietal, columellar, and palatal.
The aperture is also a small spot on the walls of pollen where the wall is weaker in order to facilitate germination. The pollen tube extends from here, breaking through the wall to transport chromosomes to the egg deep in the pistil. Number and configuration of apertures in a pollen are defined for different groups of plants; for instance, Eudictyledonae has three apertures per pollen.
Aperture may also be used to describe any otherwise-ambiguous opening in the wall of an organic structure, whether it is a cell, a shell, or a seed. In every case, the aperture is necessary to allow the passage of something that is otherwise impassible, and is a natural weak spot in the structure that can be exploited by scientists.
Web Resources On Aperture
A New Mechanism for the Regulation of Stomatal Aperture Size in Intact Leaves
Gastropods
Book Resources On ApertureMolecular Biology of the Cell by Bruce Alberts, et al
Molecular Biology of the Cell: A Problems Approach by Wilson & Hunt
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