| polar anaemia | A form of anaemia sometimes observed in natives of temperate climates when they migrate to the Arctic or Antarctic regions. (05 Mar 2000) |
|---|---|
| polar body | <cell biology> In animals each meiotic division of the oocyte leads to the formation of one large cell (the egg) and a small polar body as the other cell. Polar body formation is a consequence of the very eccentric position of the nucleus and the spindle. (18 Nov 1997) |
| polar cataract | A capsular cataract limited to an area of the anterior or posterior pole of the lens. (05 Mar 2000) |
| polar cell | <cell biology> In animals each meiotic division of the oocyte leads to the formation of one large cell (the egg) and a small polar body as the other cell. Polar body formation is a consequence of the very eccentric position of the nucleus and the spindle. (18 Nov 1997) |
| polar compound | A compound in which the electric charge is not symmetrically distributed, so that there is a separation of charge or partial charge and formation of definite positive and negative poles; e.g., H2O. See also inorganic compound. (05 Mar 2000) |
| polar fibres | Those fibres of the mitotic spindle extending from the two poles of the spindle toward the equator. Compare: astral fibres, kinetochore fibres. (05 Mar 2000) |
| polar flagellation | <cell biology> Condition of having flagella attached at one end or both ends of the cell. (09 Oct 1997) |
| polar globule | <cell biology> In animals each meiotic division of the oocyte leads to the formation of one large cell (the egg) and a small polar body as the other cell. Polar body formation is a consequence of the very eccentric position of the nucleus and the spindle. (18 Nov 1997) |
| polar granule | <biology> Granules containing a basic protein found in insect eggs that induce the formation of and become incorporated into germ cells. (18 Nov 1997) |
| polar group | <chemistry> Any chemical grouping in which the distribution of electrons is uneven enabling it to take part in electrostatic interactions. (18 Nov 1997) |
| polar lobe | <marine biology> In some molluscs a polar lobe appears as a clear protrusion close to the vegetal pole of the cell prior to the first cleavage and becomes associated with only one of the daughter cells. Removal of the first polar lobe or of any polar lobe that forms at a subsequent mitosis, leads to defects in the embryo, it seems that the polar lobe contains special morphogenetic factors. (18 Nov 1997) |
| polar mutation | <molecular biology> A mutation in a single gene which affects the rate of expression of other genes that are near it on a chromosome. (09 Oct 1997) |
| polar plasm | <cell biology, embryology> Differentiated cytoplasm associated with the animal or vegetal pole of an oocyte, egg or early embryo. (18 Nov 1997) |
| 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) |