spiral cleavage
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spiral cleavage
the division of cells in the developing animal egg in a spiral manner (see Fig. 109 ). Most invertebrate groups exhibit this type of cleavage with the exception of echinoderms, protochordates and a few smaller groups.Collins Dictionary of Biology, 3rd ed. © W. G. Hale, V. A. Saunders, J. P. Margham 2005