nucleus

• WordNet 3.6
  • n nucleus the central structure of the lens that is surrounded by the cortex
  • n nucleus a part of the cell containing DNA and RNA and responsible for growth and reproduction
  • n nucleus any histologically identifiable mass of neural cell bodies in the brain or spinal cord
  • n nucleus a small group of indispensable persons or things "five periodicals make up the core of their publishing program"
  • n nucleus the positively charged dense center of an atom
  • n nucleus (astronomy) the center of the head of a comet; consists of small solid particles of ice and frozen gas that vaporizes on approaching the sun to form the coma and tail
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• Interesting fact: A shrimp has more than a hundred pair of chromosomes in each cell nucleus.
• • Nucleus (Biol) A body, usually spheroidal, in a eukaryotic cell, distinguished from the surrounding protoplasm by a difference in refrangibility and in behavior towards chemical reagents, which contains the chromosomal genetic material, including the chromosomal DNA. It is more or less protoplasmic, and consists of a clear fluid (achromatin) through which extends a network of fibers (chromatin) in which may be suspended a second rounded body, the nucleolus (see Nucleoplasm). See Cell division, under Division.
  • Nucleus A kernel; hence, a central mass or point about which matter is gathered, or to which accretion is made; the central or material portion; -- used both literally and figuratively. "It must contain within itself a nucleus of truth."
  • Nucleus (Zoöl) A visceral mass, containing the stomach and other organs, in Tunicata and some mollusks.
  • Nucleus (Bot) A whole seed, as contained within the seed coats.
  • Nucleus (Bot) An incipient ovule of soft cellular tissue.
  • Nucleus (Astron) The body or the head of a comet.
  • Nucleus (Zoöl) The central part around which additional growths are added, as of an operculum.
  • Nucleus (Zoöl) The tip, or earliest part, of a univalve or bivalve shell.
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• • n nucleus A kernel; hence, a central mass about which matter is collected, or to which accretion is made; any body or thing that serves as a center of aggregation or assemblage; figuratively, something existing as an initial or focal point or aggregate: as, a nucleus of truth; a nucleus of civilization.
  • n nucleus In biology, the kernel of a cell, in general; a central or interior differentiated mass of protoplasm, found in nearly all cells, vegetable or animal, and consisting of an oval or rounded body composed of
  • n nucleus a nuclear membrane
  • n nucleus nuclear network, and
  • n nucleus nucleoplasm, and containing nucleoli. The nuclear network is made up of threads or fibrils which are composed of a deeply staining part, “chromatin,” and a feebly staining intermediate substance, “linin” or parachromatin (nucleohyaloplasm). In the meshes of the network is found the more fluid part of the nucleus, the nucleoplasm (achromatin, karyochylema, paralinin). Nucleoplasm, according to Carnoy, consists of a plastin network and a granular fluid, “enchylema.” The nuclear membrane is considered by some observers to be an inner limiting layer of cell-protoplasm surrounding the nucleus, by others to be a condensation of the peripheral portion of the nuclear network. There may be but one nucleus or several nuclei in one cell; and a nucleus may be nucleolate or not. Nuclei are generally proportionate in size to the cell containing them: in some instances, however, they form almost the entire cell mass. A structural difference between the nucleus and the rest of the cell-protoplasm is indicated by its greater resistance to powerful reagents, and by its varied reaction with stains. Functionally, the nucleus is the most important portion of the cell, as it is here that the complex series of changes known as karyokinesis take place, resulting in the division of the nucleus and followed by the division of the cell. This process of mitosic or indirect cell-division is found in all varieties of cells, whether vegetable or animal, fetal or adult, normal or pathological. Instances of cell-division not mitosic have, however, been noted. The nucleus of the human ovum was discovered by Purkinje in 1825, and hence is often called the corpuscle of Purkinje. Its usual name in text-books of anatomy is germinal vesicle. See cut under cell, 5.
  • n nucleus In zoology:
  • n nucleus In ascidians, the alimentary and reproductive viscera collectively, when these are aggregated into a mass, as in the salps.
  • n nucleus In protozoans, a solid rod-like or strap-shaped body, having in many cases the functions of an ovary in connection with a nucleolus (see nucleolus, 2).
  • n nucleus In echinoderms, the madreporiform body
  • n nucleus In anatomy, a collection of ganglion-cells in the brain or other portion of the cerebrospinal axis.
  • n nucleus In conchology, the embryonic shell which remains at the apex of the mature shell, as of a gastropod; also, the initial point from which the operculum of a gastropod grows. See protoconch.
  • n nucleus A body having a stronger or weaker attraction for the gas, vapor, or salt of a solution than for the liquid part of it, and therefore modifying by its presence the freezing-and boiling-points.
  • n nucleus In astronomy, the bright central point usually present in the head of a comet and often in a nebula.
  • n nucleus A genus of gastropods: same as Columbella.
  • n nucleus Same as claustrum, 1.
  • n nucleus A very small colony of honey-bees started for the purpose of rearing queens to exchange with the queens of full colonies, thus assisting in the prevention of swarming.
  • n nucleus no points at all;
  • n nucleus a perfect set. This result (set) is the nucleus EΩ.
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• • n Nucleus nū′klē-us the central mass round which matter gathers:
  • n Nucleus nū′klē-us (astron.) the head of a comet
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• Robert Collier

  

  “Plant the seed of desire in your mind and it forms a nucleus with power to attract to itself everything needed for its fulfillment.”
• Robert Collier

  

  “First the stalk -- then the roots. First the need -- then the means to satisfy that need. First the nucleus -- then the elements needed for its growth.”
• William J. Durant

  

  “The family is the nucleus of civilization.”

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