zygosomehttp://www.oed.com/dictionary/zygosome_n%3Ftab%3Dmeaning_and_usezygosome, n.
First published 1921; not fully revised

zygosomenoun

Cytology.
  1. 1905–
    1. 1905
      A similar operation of the law of chance has been suggested by Strasburger ('04) in the separation of the chromatin granules as a result of the division of the ‘zygosome’.
      Annals of Botany vol. 19 249
    2. 1910
      Grégoire.., while agreeing with the parasynaptic chromosome formation, put a different interpretation on to the ‘gamosomes’ and ‘zygosomes’ of Strasburger and Miyake.
      Annals of Botany vol. 24 727
    3. 1974
      The varying amounts of the q segments present in the zygosome may account in large measure for the physical and mental deviation of these mongoloid patients from the usual spectrum of characteristics typical of mongoloids bearing three independent chromosomes 21.
      Journal of Heredity vol. 65 257/1

Originally published as part of the entry for zygo-, comb. form

zygo-, comb. form was first published in 1921; not fully revised.