Theriogenology 1997 Oct
Synchronization of cell division in
eight-cell bovine embryos produced in vitro: Effects of
Samake S, Smith LC.
To date, methods for synchronizing the cell division of
ungulate embryos without reducing their developmental potential
have not been reliable or simple. The overall objective of this
study was to determine the reliability of aphidicolin, a
powerful inhibitor of eukaryotic DNA synthesis, to arrest and
synchronize blastomere division in cleavage-stage bovine embryos
and to assess its reversibility and toxicity in vitro.
Eight-cell stage embryos obtained at 58 h post insemination were
treated with several concentrations of aphidicolin for 12 h.
Treated embryos were assessed for cleavage arrest, chromatin
morphology and DNA synthesis; scored for blastocyst formation
and hatching rate; and fixed for determination of the number of
nuclei. Complete arrest of cell division was observed at
aphidicolin concentrations of 1.4 microM and above. At these
concentrations, no morphological alteration to interphase
chromatin was observed in treated embryos compared with the
controls. Removal of aphidicolin led to at least a 4-h delay
before resumption of DNA synthesis and cleavage. The ability of
treated embryos to reach the blastocyst stage in vitro, the
hatching rate and the number of cells per blastocyst were
significantly reduced compared with the control group. Since the
ability of treated embryos to develop to the blastocyst stage
was significantly reduced even at the minimal effective dosage,
it is concluded that aphidicolin is unlikely to provide suitable
cell cycle synchronization without damage to the embryos.