| AER | abduction/external rotation; acoustic evoked response; acute exertional rhabdomyolysis; agranular en... |
|---|---|
| CPEO | chronic progressive external ophthalmoplegia |
| EAC | Ehrlich ascites carcinoma; electroacupuncture; epithelioma adenoides cysticum; erythema annulare cen... |
| EAM | episodic ataxia with myokymia; external acoustic meatus |
| EAST | elevated-arm stress test; Emory angioplasty vs. surgery trial; external rotation, abduction stress t... |
| secretory canaliculus | See: intercellular canaliculus, intracellular canaliculus. (05 Mar 2000) |
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| intercellular canaliculus | One of the fine channels between adjoining secretory cells, such as those between serous cells in salivary glands. (05 Mar 2000) |
| intracellular canaliculus | <cell biology> A fine canal formed by invagination of the cell membrane into the cytoplasm of a cell, such as those of the parietal cells of the stomach. (05 Mar 2000) |
| tympanic canaliculus | A minute canal passing from the inferior surface of the petrous portion of the temporal bone between the jugular fossa and carotid canal to the floor of the tympanic cavity. Located in the wedge of bone separating the jugular canal and carotid canal, it transmits the tympanic branch of the glossopharyngeal nerve. Synonym: canaliculus tympanicus, Jacobson's canal, tympanic canal. (05 Mar 2000) |
| lacrimal canaliculus | A curved canal beginning at the lacrimal punctum in the margin of each eyelid near the medial commissure and running transversely medially to empty with its fellow into the lacrimal sac. Synonym: canaliculus lacrimalis. (05 Mar 2000) |
| angle of aperture | <ophthalmology, optics> The angle formed by lines drawn from the ends of the diameter of a lens to its point of focus. See: angular aperture. (05 Mar 2000) |
| angular aperture | The angle, in air, of light that passes from the object to the ends of the diameter of the front lens of the microscope objective. (05 Mar 2000) |
| anterior nasal aperture | The anterior nasal opening in the skull. Synonym: apertura piriformis, piriform opening. (05 Mar 2000) |
| aperture | <physics> The opening in an optical system which restricts the size of the bundle of rays incident on a given surface. (Usually circular and specified by diameter.) (09 Oct 1997) |
| aperture, angular | <microscopy> The angle between the most divergent rays that can pass through a lens to form the image of an object. The angle subtended between the axis of a lens and the largest accepted angle of the image-forming rays. With microscope objectives the trigonometric sine of this angle is used to define numerical aperture but as measured from the axial object point. (05 Aug 1998) |
| aperture correction | <microscopy> An electronic process used in some high-resolution video cameras and monitors that compensates for the loss in sharpness of detail due to the finite dimensions (aperture) of the scanning beam. (05 Aug 1998) |
| aperture diaphragm | A metal device that limits the area of the beam emerging from an X-ray tube. (05 Mar 2000) |
| aperture, effective | <microscopy> The diameter of the entrance pupil: it is the apparent diameter of the limiting aperture measured from the front. (05 Aug 1998) |
| aperture for electron microscopy | <technique> Anode aperture: The opening in the accelerating voltage anode shield of the electron gun through which the electrons must pass to irradiate the specimen. Condenser aperture: An opening in the condenser lens controlling the number of electrons entering the lens and the angular aperture of the electron beam. The angular aperture can also be controlled by the condenser lens current. Physical objective aperture: A metallic diaphragm, with a small central hole, used to limit the cone of electrons accepted by the objective lens. This improves image-contrast since highly scattered electrons are prevented from arriving at the Gaussian image plane and therefore cannot contribute to background fog. Aplanatic. Free from spherical aberration and coma. (05 Aug 1998) |
| aperture function | <microscopy> In a diffraction-limited optical system, the function that determines the relationship between the image and each point in the object. Modifying the aperture function changes the image according to the modified Fourier-filtering (or optical filtration) property of the aperture. (05 Aug 1998) |