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 microg/ml of colchicine for 1-4h or 0.02-0.6 microg/ml of demecolcine for 15-60 min. Cytoplasmic protrusions of oocytes were removed with a micromanipulation pipette. The results show that: 1) at 13.5-18h post-hCG injection, approximately 90% of oocytes treated for with 10 microg/ml of colchicine formed cytoplasmic protrusions, and in some oocytes enucleation occurred; 2) when treated with 0.4 microg/ml of demecolcine for 1h, cytoplasmic protrusions 13.5-18h 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 approximately 32% with blind enucleation.