Somatic nucleus remodelling in immature and mature Rassir oocyte cytoplasm.
Successful production of cloned animals derived from somatic cells has been achieved in sheep, cattle, goats, mice, pigs, rabbits, etc. But the efficiency of nuclear transfer is very low in all species. The present study was conducted to examine somatic nucleus remodelling and developmental ability in vitro of rabbit embryos by transferring somatic cells into enucleated germinal vesicle (GV), metaphase I (MI) or metaphase II (MII) oocytes. Microtubules were organized around condensed chromosomes after the nucleus had been transferred into any of the three types of cytoplasm. A bipolar spindle was formed in enucleated MII cytoplasm. Most of the nuclei failed to form a normal spindle within GV and MI cytoplasm. Some chromosomes scattered throughout the cytoplasm and some formed a monopolar spindle. Pseudopronucleus formation was observed in all three types of cytoplasm. Reconstructed embryos with MI and MII cytoplasm could develop to blastcysts. Nuclei in GV cytoplasm could develop only to the 4-cell stage. These results suggest that (1) GV material is important for nucleus remodelling after nuclear transfer, and (2) oocyte cytoplasm has the capacity to dedifferentiate somatic cells during oocyte maturation.
Zhang
Li-Sheng
LS
State Key Laboratory of Reproductive Biology, Institute of Zoology, Chinese Academy of Sciences, Beijing, 100080, P.R. China.
Zhang
Ke-Ying
KY
Yao
Li-Juan
LJ
Liu
Shu-Zhen
SZ
Yang
Cai-Xia
CX
Zhong
Zhi-Sheng
ZS
Zheng
Yue-Liang
YL
Sun
Qing-Yuan
QY
Chen
Da-Yuan
DY
D000818:Animals; D019976:Cloning, Organism; D005260:Female; D066298:In Vitro Techniques; D008677:Metaphase; D008870:Microtubules / Q000648:ultrastructure; D053652:Nuclear Transfer Techniques; D009865:Oocytes / Q000166:cytology / Q000254:growth & development / Q000648:ultrastructure*; D011817:Rabbits