Researches On The Relation Of Nucleus With Cytoplasm In Porcine Cumulus Cell Nuclear Transfer

Somatic cell nuclear transfer (SCNT) is a complex and applicable embryo biotechnology; it provides great value in researches on basic theories and applications. At the very beginning, SCNT was used to research on the function of genetic matters in cell differentiation, i.e. the relation of nucleus with cytoplasm. However, although SCNT technology has been improved and gained cloned animals, the relation of nucleus with cytoplasm during NT process is not thoroughly understood. This experiment adopted porcine cumulus cells as donor cells, porcine in-vitro maturated oocytes in MII stage as recipients; and has researched on the preactivation of recipient cytoplasm, activation process, action time of nucleus with cytoplasm, pretreatment of cumulus cells, as well as some relative issues such as the optimum follicular diameters; this experiment aimed to perform a systemic research on the relation of nucleus with cytoplasm and provide a feasible NT procedure. According to the results of the experiment, the following conclusions have been educed.1, The effect of various follicular diameters on in-vitro maturation (IVM) of porcine oocytes: the cumulus and oocyte complexes (COCs) aspirated from different diameter follicles (<3mm, 3~ 6mm, >6mm) were maturated in vitro, the oocytes with the first polarbody were judged to be mature. The result showed that the 3~6mm group had the highest maturation rate (195/412, 47.26 ±0.98%) , the secondary was >6mm group (66/204, 43.24 + 4.30%) , while the <3mm group (24/196, 12.20+0.96%) had the poorest maturation rate. The differences among the three groups were significant (P<0.01) .2, The effect of preactivation of enucleated oocytes on NT: the enucleated oocytes underwent preactivation or not has received intracytoplasmic nucleus injection. The result demonstrated that : the cleavage rate and proportion of embryos with more than 4 cells of oocytes in control group were both higher than those in preactivation group (63/177, 35.53 + 3.32% vs 45/137, 32.80 + 3.05%; 22/177, 12.40±1.20% vs 15/137, 10.80±3.00%) , but the difference between them was not significant (P>0.05) .3, The effect of simultaneous and delayed activation on NT: the cumulus cells were injected to the perivitelline of enucleated oocytes, and then the reconstructed embryos received fusion and activation simultaneously or respectively. The result indicated that: the cleavage rate and proportion of embryos with more than 4 cells of oocytes in delayed activation group were both higher than...