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With the in-depth exploration of all stages in early-stage embryos, in particular zygotic genome activation and first cell lineage differentiation, researchers have found that early embryonic epigenetics follows a strict pattern of temporal and spatial modification. Previous studies have determined the inhibitory effect of H3K9me3 and H3K27me3 on genomic expression, and found that they are involved in many core biological events in the genome such as chromatin reprogramming, genomic imprinting, maintenance of embryonic stem cell pluripotency and somatic cell nuclear transfer, though the detailed molecular mechanism has remained elusive. From the point of developmental biology and epigenetics, this article has expounded the research progress on the methylation of H3K9 and H3K27 histones in early-stage embryos, which may provide a clue for the complex mechanism of embryonic development and improvement of culture method for embryos in vitro.
Subject(s)
Female , Humans , Pregnancy , Chromatin , Embryonic Development , Epigenesis, Genetic , Gene Expression Regulation, Developmental , Histones/metabolism , MethylationABSTRACT
Objective To investigate ectopic pregnancy from embryo transfer (ET)of in-vitro fertilization (IVF) cycle and intracytoplasmic sperm iujection (ICSI) cycle and frozen-thawed (FET) cycle.Methods From Jan.2005 to Dec.2010,a total of 9037 IVF-ET or ICSI-ET cycles and 4034 FET cycles were performed in our reproductive medicine center,Affiliated First Hospital of Zhengzhou University.The incidence of ectopic pregnancy rate was studied in fresh cycles IVF-ET (5998) and ICSI-ET (3039) cycles,and natural FET (2198) and hormone replacement (E-P) FET (1836) cycles.ResultsOf 4034 FET cycles,1090 clinical pregnancies and 26 ectopic pregnancies were observed,the incidence of ectopic pregnancy was 2.38％ (26/1090).Of 9037 fresh cycles,3602 cycles were clinical pregnancy,and 133 cycles were ectopic pregnancy,and the incidence of ectopic pregnancy was 3.69％ (133/3602).The ectopic pregnancy rate in FET cycles was lower than in fresh cycles significantly (P ＜0.05).Of 3039 fresh ICSI-ET cycles,the incidence of ectopic pregnancy was 2.62％ ( 34/1298 ) in 1298 clinical pregnancies.Of 5998 IVF-ET cycles,2304 clinical pregnancies were observed,the incidence of ectopic pregnancy was 4.30％ (99/2304).Ectopic pregnancy rate in the fresh ICSI-ET cycles was lower than that of IVF-ET group significantly (P ＜ 0.01 ).The ectopic pregnancy rate in the natural FET cycles was 1.46％ (8/547),which was significantly lower than 3.31％ ( 18/543 ) in E-P group ( P ＜ 0.05 ).ConclusionsThe incidence of ectopic pregnancy of FET cycles was significantly lower than that of fresh embryo transfer cycles.The application of exogenous sex hormones in assisted reproductive cycles might increase occurrence of ectopic pregnancy.
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Objective To evaluate the effects on pregnancy outcome of freezing time from oocyte retrieval and thawing method for metaphase Ⅱ human oocytes vitrification. Methods From Mar 2007 to Mar 2009, the clinical outcome of 30 infertile women undergoing vitrified-thawing oocytes of in vitro fertilizationembryo transfer(IVF-ET) in the Reproductive Medical Center of the First Affiliated Hospital of Zhengzhou University was studied retrospectively, including 21 women with double fallopian tube obstruction and 9 women's husband azoospermia. All infertile women were divided into three groups, including 5 cases in group A (freezing between 4 and 5 hours from oocyte retrieval and conventional thawing method), 9 cases in group B (freezing within 2 hours from retrieval and conventional thawing method) and 16 cases in group C (freezing within 2 hours from retrieval and improved thawing method). The vitrified oocytes were preserved for 2 months to I year and thawed for Intracytoplasmic sperm injection (ICSI) and embryo transfer. The outcome of IVF and pregnancy were recorded. Results (1) The rates of oocyte survival was (65±33) % in group B and (72±23)% in group C and the rate of transfer cycle was 9/9 in group B and 16/16 in group C, which were all significantly higher than (16±17) % of oocyte survival and 1/5 of transfer cycle in group A (P = 0. 001,0. 021). However, the rate of oocyte survival and transfer cycle between group B and group C did not reach statistical difference (P > 0. 05). The rate of implantation and clinical pregnancy of (33±38) % and 9/16 in group C were significantly higher (4±11)% and 1/9 in group B (P =0. 033,0. 040).(2)The mean age of women in group C were (28.6±2.1) in oneself oocyte, (28.0±4.6) in donor oocyte and (28.1±3.4) in donor sperm. The rate of oocyte survival was (73±25) %, (88±10) % and (66±25) %. The rate of fertilization rate was (84. 6±0. 9) %, (79. 3±2. 0) % and (82. 8±15.0) %. The rate of implantation was (20. 0±44. 7) %, (33. 0±0. 1) % , (41.6±41.7) %. The rate of clinical pregnancy was 1/5 in oneself cycles,3/3 in donor oocyte cycles, 5/8 banked donor sperm cycles in group C. All above clinical parameters were not statistically different (P >0. 05). (3) In group A, one women underwent IVFET and no clinical pregnancy was observed. One women pregnancy was terminated at two months in group B.The clinical pregnancies rate of group C was 9/16, late abortion occurred in 1 woman, the other 8 women underwent term pregnancy, including 5 male infants and 4 female infants. All of infants showed normal Karyotype. Live-birth rates per warmed oocyte was 5.9% (8/135). The mean gestational weeks and birth weight of the infants were (39. 4±0. 9) weeks and (3574±569) g, respectively. Conclusions Embryo quality and clinical outcome of thawing cycles could be significantly improved when oocyte vitrification was performed within 2 hours from oocyte retrieval and improved thawing method.
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Objective To investigate the incidence of and clinical factors influencing neonatal birth defects from different assisted reproductive technology. Methods Between October 1998 and December 2006,1271 newborns from mothers treated by in vitro fertilization techniques [ including in vitro fertilization (IVF), intracytoplasmic sperm injection (1CSI) and thaw embryo transfer (Thaw-ET) ] matched with 269 newborns from mothers treated by artificial insemination were enrolled in Reproductive Medicine Center in First Hospital Affiliated to Zhengzhou University. Their medical information was analyzed retrospectively to compared neonatal characteristics, the incidence of birth defect and anomalous organs involved between in vitro fertilization group and artificial insemination group. Results In group of in vitro fertilization, those newborns with low birth weight from IVF, ICSI and Thaw-ET were 20. 0% ( 134/671 ), 22. 4% (92/410), 18.9% (36/190)respectively, which were more than 11.5% (31/269) cases in group of artifical semination with statistical significance (P < 0. 05 ). The rates of multiple pregnancy of 23.8% ( 160/671 ), 25.4% (104/410) ,21.1% (40/190) in subgroup of 1VF, ICSI and Thaw-ET were significantly higher than 10. 0% ( 27/269 ) in group of artifical insemination( P < 0. 05 ). The rate of macrosomia in group of in vitro fertilization was significantly lower than that of artificial insemination group (3.9% vs 8. 2%, P <0.05). However, the incidence of birth defect involved in various organs did not show significant difference between two groups ( P>0.05 ). Conclusions The incidence of multiple pregnancy demonstrated obviously increasing trends born with various In Vitro Fertilization techniques, which pave the way to high risk pregnancy. However, the incidence of newborn birth defect was not increased significantly. Thus, to lower occurrence of multiple pregnancy was the key approach to obtain neonates health.
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Objective To compare the advantages of three-dimensional(3D) and two-dimensional(2D) ultrasound in embryo transfer. Methods A total of 319 patients accepted embryo transfter were included in this study. 2D and 3D ultrasound were used to investigate the uterine cavity and transfer distance from the fundus (TDF),respectivly. They were divided into four groups according to TDF difference(D-TDF) between 2D and 3D ultrasound(group of DTDF<3mm,group of DTDF3～5mm,group of 6～9 mm,group of DTDF≥10 mm. Pregnancy outcomes among the four groups were compared. Results Of the 319 patients, 41 were observed to have abnormal uterine cavity. For 140 patients, the TDF measured by 2D ultrasound were different from that measured by 3D ultrasound. Clinical pregnancy rate and implantation rate were found lowest in group of TDF≥10 mm mm (7.7% vs 34.1%,38.1% ,40.0% and 3.6% vs 18.2% ,21.2% ,20.0%, P <0.05). Conclusions 2D ultrasound is limit and deficient for embryo transfer, especially for the visualization of uterine cavity and location of catheter tip, however, it may be better achieved with 3D ultrasound. It is helpful to use the 3D ultrasound to place the catheter tip accurately and improve the pregnancy rate of embryo transfer.