poison seta 1. (ANN: Polychaeta) Elongate pungent chitinous bristles that project from the parapodia, may be hollow and filled with fluid, contain retrorse spinules along the staff, or be needlelike in appearance. 2. (arthrO: Insecta) Hollow seta through which they discharge an irritating secretion from the venom glands.
polar body A minute, functionless cell produced and discarded during the development of an oocyte.
polar cap (MESO) The eight anterior cells in the nematogen.
polar field/plate (CTENO) One of two long ciliated depressions in the floor of the statocyst.
polarity n. [L. polus, axis] The condition of having opposite poles or qualities.
polarization n. [L. polus, axis] 1. A potential difference across a membrane. 2. Light that is filtered to vibrate in one plane only.
polar plates 1. (CNID) Balance organs of two narrow ciliated bands in the transverse plane. 2. (CTENO) see polar field/plate.
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