In order to make a cloned animal, the nucleus of the egg must first be removed. However, it is very difficult to find a transparent nucleus from a mouse egg with a diameter of 80 μm, suck it into a glass tube with a diameter of 10 μm, and remove it.
2. Removal of somatic cell (cumulus) membrane
The somatic cells of the mouse are broken with an injection needle with a diameter of 5 μm, and the nucleus is removed from the inside. If you break the nucleus when you break the cell membrane, you can no longer clone.
3. Injection of somatic cell nuclear into oocyte cytoplast
A nucleus, with its membrane removed, is injected into an enucleated mouse oocyte (cytoplast). The technique of injecting the nucleus without rupturing the oocytes is so difficult that it is considered a specialized skill.
