Morura splitting: letting embryos grow to the 32-cell stage before splitting into two identical embryos.

Somatic Cell Nuclear transfer

• Cloning usually begins with removal of the egg nucleus from a fertilized egg and replacement with another nucleus (possibly from an adult animal like a cow).

Oocytes (Scottish Blackface ewes) between 28 and 33 h after injection of gonadotropin-releasing hormone (GnRH), and enucleated as soon as possible.

Quiescent, diploid donor cells: reducing serum 10% to 0.5% for 5 days, arrest in G0 （confirmed by antiPCNA/cyclin antibody)

Electrical pulses fusion: the donor cell to the enucleated oocyte

The majority of reconstructed embryos were cultured in ligated oviducts of sheep

Primordial germ cells isolatation.

The germ cells isolated from fetal are more stable cells and can be cultured and frozen for indefinite periods of time.

The germ cells can be stimulated to divide rapidly and can grow to create identical cells.