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 for Segmentation of the ovum
From The Collaborative International Dictionary of English v.0.48 :

  Segmentation \Seg`men*ta"tion\, n.
     The act or process of dividing into segments; specifically
     (Biol.), a self-division into segments as a result of growth;
     cell cleavage; cell multiplication; endogenous cell
     [1913 Webster]
     Segmentation cavity (Biol.), the cavity formed by the
        arrangement of the cells in segmentation or cleavage of
        the ovum; the cavity of the blastosphere. In the gastrula
        stage, the segmentation cavity in which the mesoblast is
        formed lies between the entoblast and ectoblast. See
        Illust. of Invagination.
     Segmentation nucleus (Biol.), the body formed by fusion of
        the male and female pronucleus in an impregnated ovum. See
        the Note under Pronucleus.
     Segmentation of the ovum, or Egg cleavage (Biol.), the
        process by which the embryos of all the higher plants and
        animals are derived from the germ cell. In the simplest
        case, that of small ova destitute of food yolk, the ovum
        or egg divides into two similar halves or segments
        (blastomeres), each of these again divides into two, and
        so on, thus giving rise to a mass of cells (mulberry mass,
        or morula), all equal and similar, from the growth and
        development of which the future animal is to be formed.
        This constitutes regular segmentation. Quite frequently,
        however, the equality and regularity of cleavage is
        interfered with by the presence of food yolk, from which
        results unequal segmentation. See Holoblastic,
        Meroblastic, Alecithal, Centrolecithal,
        Ectolecithal, and Ovum.
     Segmentation sphere (Biol.), the blastosphere, or morula.
        See Morula.
        [1913 Webster]

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