Nuclear Transfer and Activation
All micromanipulations are carried out in Hepes buffered
media. In our laboratory we use a SOF Hepes-based formulation
(Gardner et al., 1994) supplemented with 6 mg/ml of
BSA and/or 10% FCS for zona-free work. The zona pellucida
of in vitro matured oocytes is very thick and heterogeneous,
and due to hardening it is difficult to penetrate with a
bevelled standard pipette such as those used for enucleating
in vitro matured oocytes of other species. As a result, the
zona-enclosed conventional method for enucleation is more
difficult and less efficient. Moreover, the transfer of the
donor cell into the perivitelline space results in poor contact
between the oocyte and somatic cell membranes, thus
reducing the chance of successful electrofusion (Lagutina
et al., 2005; Li et al., 2002) even at high voltage. Further,
the presence of the zona pellucida acts as an electrical
shield that requires an increase in the voltage of fusion to
2–2.5 kV/cm, and this high voltage reduces subsequent
cleavage of the reconstructed embryos. Therefore, two
methods have been used to overcome this problem: the use
Nuclear Transfer and Activation
All micromanipulations are carried out in Hepes buffered
media. In our laboratory we use a SOF Hepes-based formulation
(Gardner et al., 1994) supplemented with 6 mg/ml of
BSA and/or 10% FCS for zona-free work. The zona pellucida
of in vitro matured oocytes is very thick and heterogeneous,
and due to hardening it is difficult to penetrate with a
bevelled standard pipette such as those used for enucleating
in vitro matured oocytes of other species. As a result, the
zona-enclosed conventional method for enucleation is more
difficult and less efficient. Moreover, the transfer of the
donor cell into the perivitelline space results in poor contact
between the oocyte and somatic cell membranes, thus
reducing the chance of successful electrofusion (Lagutina
et al., 2005; Li et al., 2002) even at high voltage. Further,
the presence of the zona pellucida acts as an electrical
shield that requires an increase in the voltage of fusion to
2–2.5 kV/cm, and this high voltage reduces subsequent
cleavage of the reconstructed embryos. Therefore, two
methods have been used to overcome this problem: the use
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