Study On Developmental Potential And Origin Of Denuded Oocytes In Mice

The occurrence,development and maturation of oocytes are the core and basis of the research on the modern reproductive biology,and the maturation of oocytes is the difficulty and key of reproductive development.There are many factors that affect the oocytes maturation,of which the cumulus cells surrounding the oocytes is the core factors affecting oocytes maturation.The maturation rate and the following developmental potential of the denude oocytes were lower than the cumulus oocytes complexes.At present,the low oocytes maturation rate is not only restricted to the further development of the oocytes,but also restricts the full use of oocytes resources.Forskolin can inhibit the recovery of oocyte meiosis,and PD166285 can promote the synthesis of MPF,thus promoting the recovery of meiosis.The spindle assembly and the distribution of cortical granules can be used to evaluate the quality of oocytes quality.The occurrence of the mammalian oocytes is a complicated process of cell differentiation,which is susceptible to the environment.Stress,especially heat stress,is one of the biggest problems of the individual.It is the damage to the reproductive function.But what and how heat stress effect on oocytes quality and apoptosis of cumulus cells has not been reported.Therefore,this study set mice as the research object,through short-term addition of forskolin to inhibit nuclear maturation process,add PD166285 promote the resumption of meiosis,to observa the function of forskolin and PD166285 on oocyte maturation rate,and to detect the mature oocytes quality.The development of the matured oocytes in vitro was further detected by IVF-ET.And hematoxylin eosin staining and TUNEL apoptosis detection to observa the apoptosis of cumulus cell,attempts to reveal how the heat stress effevt on the origin of denude oocytes.Experiment 1 was designed to reveal the effect of forskolin and PD166285 on mouse oocytes maturation efficiency and quality of matured oocytes.The immature GV phase oocytes obtained in vitro were randomly allocated to forskolin,PD and no medcine group.Detect the maturation rate and spindle assembly/distribution of cortical granules of two groups.The results showed that the addition of PD166285 and forskolin could improve the in vitro maturation rate of denude oocytes,and improve the quality of matured oocytes.Experiment 2 was designed to investigate the possibility of the denude oocytes developing to the individuals.Matures oocytes was fertilized through in vitro fertilization and 2-cell stage embryo was transfer into pseudopregnant 0.5dpc receptor female rats.We have first obtained the mice by the denude oocytes.It is proved that the denude oocytes has the potential of developing to the individual.Experiment 3 was designed to reveal the relationship between the heat stress and the origin of denude oocytes.After heat stress treatment,paraffin sections of ovary were made.The decline of oocytes number of mice ovary and apoptosis of the cumulus cells was detected by HE staining and TUNEL apoptosis detection.The results showed that the number of oocytes in control group was significantly higher than that in heat treatment group.Ovarian cumulus cells coated 2-5 layer number of oocytes was significantly higher than the control group.The apoptosis of cumulus cells was significantly lower than that of the heat stress treatment group.The results show that heat stress can result in the production of denuded oocytes.To sum up,this paper found that denuded oocytes co culture with forskolin,PD166285 can increase the maturation rate and the quality of matured oocytes.It is proved that offspring can derived from the denuded oocytes under the suitable conditions,and provide a more extensive source of oocytes for the livestock production,and also provide some help for the treatment of infertility.The effect of heat stress on the formation of denuded oocytes in mammals were studied.