Effects of colchicine or demecolcine on cytoplasmic protrusions and assisted enucleation of golden hamster oocytes

To establish experimental protocols for cloning golden hamsters, optimal concentrations of colchicine and demecolcine were determined for inducing cytoplasmic protrusion (containing chromosomes) and assisting enucleation of their oocytes. Denuded oocytes at different ages were treated with 2.5-10 μg/ml of colchicine for 1-4 h or 0.02-0.6 μg/ml of demecolcine for 15-60 min. Cytoplasmic protrusions of oocytes were removed with a micromanipulation pipette. The results show that: 1) at 13.5-18 h post-hCG injection, ∼90% of oocytes treated for with 10 μg/ml of colchicine formed cytoplasmic protrusions, and in some oocytes enucleation occurred; 2) when treated with 0.4 μg/ml of demecolcine for 1 h, cytoplasmic protrusions 13.5-18 h post-hCG treatment were present in almost all oocytes; 3) after the protrusions induced by either treatment had been removed, the assisted enucleation rate was >80%, whereas it was ∼32% with blind enucleation.