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The developmental potential of the inner cell mass of blastocysts that were derived from mouse ES cells using nuclear
1Laboratory of Animal Reproduction, College of Agriculture, Kinki University, 3327-204, Nakamachi, Nara, 631-8505, Japan.
Abstract:
The present study examined the causes of the low developmental potential of enucleated oocytes that have received ES cells and consequent postnatal death of the young. The inner cell masses (ICM) of nuclear-transferred blastocysts or diploid blastocysts were injected into tetraploid blastocysts (group B) or nuclear-transferred tetraploid blastocysts (group C), respectively. The developmental potential of these groups was compared with tetraploid blastocysts injected with ICM of diploid blastocysts (group A). The potential of reconstituted blastocysts to develop into live young in group B increased slightly (5%) but was significantly lower than that in group A (45%). The rate of postnatal death of young in group B did not decrease. The implantation rate of reconstituted blastocysts in group C was very low and no live fetuses were obtained. The results of the present study indicate that the inferior potential of both ICM and trophectoderm cells of nuclear-transferred blastocysts underlies the low developmental rate of nuclear-transferred oocytes receiving ES cells and the higher rate of postnatal death of ES cell-derived young.
Insights
This study investigated why enucleated oocytes receiving embryonic stem (ES) cells have low developmental potential and cause postnatal death. Results show nuclear-transferred blastocysts have inferior cell potential, leading to poor development and increased mortality.
Area of Science:
- Reproductive Biology
- Developmental Biology
- Stem Cell Research
Background:
- Enucleated oocytes receiving embryonic stem (ES) cells exhibit limited developmental potential.
- Postnatal mortality is a significant issue in offspring derived from such reconstructed embryos.
Purpose of the Study:
- To elucidate the underlying causes of poor developmental potential in enucleated oocytes reconstructed with ES cells.
- To identify factors contributing to the high rate of postnatal death in ES cell-derived young.
Main Methods:
- Comparison of developmental potential across three groups of reconstituted blastocysts: Group A (diploid ICM into tetraploid blastocysts), Group B (nuclear-transferred blastocyst ICM into tetraploid blastocysts), and Group C (diploid blastocyst ICM into nuclear-transferred tetraploid blastocysts).
- Assessment of implantation rates and live birth rates in each group.
Main Results:
- Group B showed a slight increase (5%) in live young development compared to controls, but significantly lower than Group A (45%).
- Postnatal death rates in Group B did not decrease.
- Group C exhibited very low implantation rates, with no live fetuses obtained.
Conclusions:
- The inferior developmental potential of both inner cell mass (ICM) and trophectoderm cells from nuclear-transferred blastocysts is responsible for the low developmental rate.
- These cellular defects also contribute to the increased postnatal mortality observed in ES cell-derived offspring.