In natural cycles,the FSH threshold of antral follicle cochort is different.For that reason,the development of each follicle is not synchrony.The mechanism of which follicle will develop and how many follicles can dev...In natural cycles,the FSH threshold of antral follicle cochort is different.For that reason,the development of each follicle is not synchrony.The mechanism of which follicle will develop and how many follicles can develop is not sure.The destined to be matured oocyte follicle should be gathered during luteal-follicular transition phase.The luteal-follicular transition phase is defined as the period from previous luteal phase at which time the estrodial and progesterone reduced dramatically to the selection phase of next cycle.It is indicated by menorrhea and regarded as an important transition phase in normal cycles.The FSH begins to elevate 2 days before menorrhea.Follicles were collected during that period.The elevation of FSH during luteal-follicular transition phase is important for follicle collection,selection and can prevent follicle atresia.The asychronization of follicles in controlled ovary stimulation can reduce available oocytes and embryos,and subsequently reduce pregnancy rate.The reason of follicle asychronization could be the following:1.Advanced age.In aging women,the follicular phase is advanced.The antral follicles were asynchrony in size when Gn injection at early follicular phase.2.The threshold of each follicular is quite different,or the initiate dose of Gn is not enough for the follicle development.The follicles with less sensitivity grow slower.That is probably one of the reasons of follicle asynchrony.3.It is the intrinsic characteristic of COS.In GnRH antagonist protocol and GnRH agonist flare-up protocol,the FSH is not inhibited during luteal phase.The follicle collection begins before Gn injection.The Gn promotes the asynchrony of follicle.The elevation of FSH at luteal-follicular transition phase is the main reason of asynchrony.The purpose of improvement follicular synchronization is to reduce the FSH level during luteal-follicular transition phase.The antral follicles keeping quiescence before Gn injection will be benefit for collection of more synchrony follicles.The protocols include GnRH agonist long protocol,steroid pretreatment,GnRH antagonist pretreatment,et al.For the protocols of improvement follicular synchrony were different,their influence on IVF outcome needs further investigation.展开更多
文摘In natural cycles,the FSH threshold of antral follicle cochort is different.For that reason,the development of each follicle is not synchrony.The mechanism of which follicle will develop and how many follicles can develop is not sure.The destined to be matured oocyte follicle should be gathered during luteal-follicular transition phase.The luteal-follicular transition phase is defined as the period from previous luteal phase at which time the estrodial and progesterone reduced dramatically to the selection phase of next cycle.It is indicated by menorrhea and regarded as an important transition phase in normal cycles.The FSH begins to elevate 2 days before menorrhea.Follicles were collected during that period.The elevation of FSH during luteal-follicular transition phase is important for follicle collection,selection and can prevent follicle atresia.The asychronization of follicles in controlled ovary stimulation can reduce available oocytes and embryos,and subsequently reduce pregnancy rate.The reason of follicle asychronization could be the following:1.Advanced age.In aging women,the follicular phase is advanced.The antral follicles were asynchrony in size when Gn injection at early follicular phase.2.The threshold of each follicular is quite different,or the initiate dose of Gn is not enough for the follicle development.The follicles with less sensitivity grow slower.That is probably one of the reasons of follicle asynchrony.3.It is the intrinsic characteristic of COS.In GnRH antagonist protocol and GnRH agonist flare-up protocol,the FSH is not inhibited during luteal phase.The follicle collection begins before Gn injection.The Gn promotes the asynchrony of follicle.The elevation of FSH at luteal-follicular transition phase is the main reason of asynchrony.The purpose of improvement follicular synchronization is to reduce the FSH level during luteal-follicular transition phase.The antral follicles keeping quiescence before Gn injection will be benefit for collection of more synchrony follicles.The protocols include GnRH agonist long protocol,steroid pretreatment,GnRH antagonist pretreatment,et al.For the protocols of improvement follicular synchrony were different,their influence on IVF outcome needs further investigation.
