The interaction between nucleus and cytoplasm can be explored through
nuclear transfer. We describe here another tool to investigate this
interaction: MII meiotic apparatus transfer (MAT) between mouse oocytes. In
this study, the MII oocyte meiotic apparatus or spindle from C57BL/6 mice, a
black strain, was transferred into an enucleated metaphase oocyte from
Kunming mouse, a white strain. The results showed that the enucleation rate
by treating oocytes with 3% sucrose was 100%, but the electrofusion
efficiency was very low, with only 17.6% of reconstructed karyoplast-recipient
cytoplasm pairs fused. When the fused oocytes were exposed to spermatozoa
from C57BL/6 mice, 9 of 11 (82%) were fertilised. Eight reconstructed
embryos at 1- to 4-cell stages were transferred into the oviducts of two
synchronously pregnant Kunming strain fosters and one delivered two normal
C57BL/6 offspring. This study indicates that MII meiotic apparatus or
spindle sustains normal structure and function after micromanipulation
and electrofusion. MAT provides a model for further research on the
application of this technique to assisted human reproduction.