| polar plasm | <cell biology, embryology> Differentiated cytoplasm associated with the animal or vegetal pole of an oocyte, egg or early embryo. (18 Nov 1997) |
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| polar plates | Condensed platelike bodies at the ends of the spindle during mitosis of certain types of cells. (05 Mar 2000) |
| polar presentation | The presentation of either pole of the foetal oval; may be either a cephalic or breech presentation, or a longitudinal lie. (05 Mar 2000) |
| polar ring | A thickened, electron-dense ring at the anterior end of certain stages of the Apicomplexa; part of the apical complex characteristic of these sporozoans. (05 Mar 2000) |
| polar solvents | Solvent's that exhibit polar forces on solutes, due to high dipole moment, wide separation of charges, or tight association; e.g., water, alcohols, acids. (05 Mar 2000) |
| polar star | One of the figures forming the diaster. Synonym: polar star. (05 Mar 2000) |
| polar zone | The region in the vicinity of an electrode applied to the body. See: electrotonus. (05 Mar 2000) |
| electro-polar | <physics> Possessing electrical polarity; positively electrified at one end, or on one surface, and negatively at the other; said of a conductor. Source: Websters Dictionary (01 Mar 1998) |
| zinco-polar | <physics> Electrically polarized like the surface of the zinc presented to the acid in a battery, which has zincous affinity. Source: Websters Dictionary (01 Mar 1998) |
| law of polar excitation | A given segment of a nerve is irritated by the development of catelectrotonus and the disappearance of anelectrotonus, but the reverse does not hold; i.e., excitation occurs at the cathode when the circuit is closed and at the anode when it is opened. Synonym: Pfluger's law. (05 Mar 2000) |
| annular cataract | Congenital cataract in which a central white membrane replaces the nucleus. Synonym: disk-shaped cataract, life-belt cataract, umbilicated cataract. (05 Mar 2000) |
| arborescent cataract | An obsolete term for dendritic cataract. (05 Mar 2000) |
| atopic cataract | A cataract associated with atopic dermatitis. (05 Mar 2000) |
| axial cataract | A lenticular opacity in the visual axis of the lens. (05 Mar 2000) |
| black cataract | A cataract in which the lens is hardened and of a dark brown colour. In the 19th century, German black cataract meant gutta severa (q.v.). Synonym: cataracta brunescens, cataracta nigra. (05 Mar 2000) |