nuclei

1 definition found

nuclei - Collaborative International Dictionary of English v.0.48 :

  Nucleus \Nu"cle*us\, n.; pl. E. Nucleuses, L. Nuclei. [L., a
     kernel, dim. fr. nux, nucis, nut. Cf. Newel post.]
     [1913 Webster]
     1. 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.
        [1913 Webster]
  
              It must contain within itself a nucleus of truth.
                                                    --I. Taylor.
        [1913 Webster]
  
     2. (Astron.) The body or the head of a comet.
        [1913 Webster]
  
     3. (Bot.)
        (a) An incipient ovule of soft cellular tissue.
        (b) A whole seed, as contained within the seed coats.
            [1913 Webster]
  
     4. (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.
        [1913 Webster +PJC]
  
     Note: The nucleus is sometimes termed the endoplast or
           endoblast, and in the protozoa is supposed to be
           concerned in the female part of the reproductive
           process. See Karyokinesis.
           [1913 Webster]
  
     5. (Zool.)
        (a) The tip, or earliest part, of a univalve or bivalve
            shell.
        (b) The central part around which additional growths are
            added, as of an operculum.
        (c) A visceral mass, containing the stomach and other
            organs, in Tunicata and some mollusks.
            [1913 Webster]