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101.
102.
The molecular mechanisms of oocyte maturation and early embryonic development are unveiling new insights into reproductive medicine 总被引:9,自引:1,他引:9
The purpose of the present review is to outline the current understanding
on the molecular mechanisms governing various stages of oocyte maturation,
transition from maternal to embryonic control and the initial steps of
pre-embryo development. The cytoplasmic and nuclear maturation of the
oocyte during pre-ovulatory development can be viewed as separate entities.
Cytoplasmic maturation and the acquisition of stores of RNA and protein
dominates oocyte development between the premordial and pre-ovulatory
stages of development. Initiation of nuclear maturation is marked by the
breakdown of the nuclear envelope, or germinal vesicle and is triggered by
the midcycle luteinizing hormone peak. In vitro, this is associated with a
decrease in the intracellular concentrations of cAMP. This and several
subsequent steps of meiosis are controlled by the M-phase promoting factor
(MPF). While the constituents of MPF, p34cdc2 kinase and B-type cyclin, are
also present in mitotically dividing cells, in meiotically dividing oocytes
the regulation of MPF activity differs. An oocyte- specific protein kinase,
c-mos, plays an important role in up- regulating the activity of MPF at
various stages of final oocyte maturation. Several lines of evidence
suggest that the proper function of the c-mos-MPF system is associated with
important features of the last stages of oocyte maturation such as the
resumption of meiotic maturation, inhibition of DNA replication between
meiosis I and II, and the maintenance of the oocyte at metaphase II arrest
until it is fertilized. Eventually the destruction of c-mos and active MPF
following fertilization allows the initiation of mitotic cell division in
the pre-embryo. The very first cell divisions of the human pre- embryo are
still under the control of maternally inherited mRNA and protein. Several
lines of evidence suggest that in humans, zygotic gene expression is
initiated between the 4- and 8-cell stages, after which the pre-embryo
begins to utilize its own genes. Some of the first genes to be expressed in
the human pre-embryo encode proteins that are associated with cell
division, extracellular growth modulatory signals as well as factors
associated with implantation. We acknowledge that most of the data
presented comes from species other than human, therefore at present the
full biological role of the proposed regulatory pathways and control
mechanisms for human biology remains speculative.
相似文献
103.
超声血管造影在肝癌介入治疗前后的应用价值 总被引:5,自引:0,他引:5
目的探讨超声血管造影对原发性肝癌(HCC)在经皮肤动脉栓塞术(TAE)治疗前后的应用价值。方法采用超声造影剂Levovist经肘静脉注入的方法,检查12例HCC患者在TAE治疗前后血供的变化情况。要用彩色多普勒血流显像(CDFI)的半定量测量方法,判定栓塞前后肿瘤血供的丰富程度,并与X线数字减影血管造影(DSA)进行对比分析。结果超声血管造影与DSA在探查肝癌TAE治疗前后肿瘤血供方面无差异(P〉 相似文献
104.
105.
Kibbelaar RE; Mulder JW; Dreef EJ; van Kamp H; Fibbe WE; Wessels JW; Beverstock GC; Haak HL; Kluin PM 《Blood》1993,82(3):904-913
Fluorescence in situ hybridization (FISH) is a powerful tool for detection of numerical and structural chromosomal aberrations. We have compared conventional banding techniques and FISH for the detection of monosomy 7 (-7) and trisomy 8 (+8) in 89 patients with myeloid malignancies. Of these patients, 21 had -7, 30 had +8, four had both, and 34 had no aberrations or aberrations other than -7 or +8 as assessed by banding techniques. Sequential samples were available in 23 patients. Alphoid DNA probes specific for chromosomes no. 7 and 8 were used for FISH. As controls, 10 normal bone marrow (BM) samples were hybridized with the chromosomes no. 7 and 8 probes, and in addition all tumor samples were hybridized with a chromosome no. 1 specific probe. The cut-off value for -7 was 18% one-spot cells, and for +8 was 3% three-spot cells. FISH analysis of 44 samples with -7 or +8, and at least 10 metaphases evaluated, showed that the proportions of aberrant metaphase cells mirrored the interphase clone sizes. Most samples with nonclonal metaphase aberrations, including those with only a few metaphases, had increased numbers of aberrant interphase cells: 20% to 80% for -7, and 3% to 43% for +8. Interphase cytogenetics of the 34 samples without -7 or +8 did not show significant cell populations with -7 or +8. In four patients, -7 or +8 could not be confirmed by FISH due to additional structural aberrations, marker chromosomes, or wrongly interpreted banding results. As FISH will be used more and more in cytogenetic diagnosis, clinical follow-up, and therapy monitoring, it will be necessary to standardize FISH procedures and supplement the Standing Committee on Human Cytogenetic Nomenclature (ISCN) definitions of a clone with criteria specifically for in situ hybridization. 相似文献
106.
WE Gillies FRACO FRACS FRCS AMY Brooks MD PhD FRACS FRACO FRACP 《Clinical & experimental ophthalmology》1994,22(4):249-253
Background : Fistulising trabeculotomy has been used for nearly 20 years to combine the minimally invasive surgery of trabeculotomy with production of a subconjunctival fistula.
Methods : The canal of Schlemm was unroofed 2mm on one side of a 3mm half-thickness scleral flap. A trabeculotomy probe was passed about 30° along the canal on the opposite side and rotated into the anterior chamber.
Results : Of 99 eyes of 74 patients, 35 eyes of 25 patients were available for follow-up at 10 or more years. The mean IOP was 14 ± 4 mmHg (range 7 to 23 mmHg) from a preoperative IOP of 29 ± 8 mmHg (17 to 60 mmHg). Results in 44 similar patients undergoing trabeculectomy and 44 undergoing fistulising trabeculotomy were very similar at five-year follow-up.
Conclusion : Fistulising trabeculotomy was effective for lowering intraocular pressure with a low complication rate and a large area of subconjunctival fistulisation. 相似文献
Methods : The canal of Schlemm was unroofed 2mm on one side of a 3mm half-thickness scleral flap. A trabeculotomy probe was passed about 30° along the canal on the opposite side and rotated into the anterior chamber.
Results : Of 99 eyes of 74 patients, 35 eyes of 25 patients were available for follow-up at 10 or more years. The mean IOP was 14 ± 4 mmHg (range 7 to 23 mmHg) from a preoperative IOP of 29 ± 8 mmHg (17 to 60 mmHg). Results in 44 similar patients undergoing trabeculectomy and 44 undergoing fistulising trabeculotomy were very similar at five-year follow-up.
Conclusion : Fistulising trabeculotomy was effective for lowering intraocular pressure with a low complication rate and a large area of subconjunctival fistulisation. 相似文献
107.
108.
The osteolysis associated with cat-scratch fever resembles more ominous conditions. The combination of osteolysis and unilateral regional adenopathy in a child or adolescent should suggest cat-scratch disease. 相似文献
109.
病例简介:患者,女,46岁。右上腹持续性疼痛,且向右侧腹、腰部放射。伴恶心,呕吐2次。疼痛发生后自觉肠蠕动减弱,无排便。发病以来无发热、末战。既往史:高血压,高胆固醇血症,胆囊疾病。2周前行胆囊切除术,术后无并发症发生,饮食正常。个人史:无吸烟及饮酒史。体格检查:意识清晰,查体合作。生命体征正常,心率84次/min,心律匀齐,血压124/76mmHg(1mmHg=0.133kPa),心肺功能正常。肠呜音减弱,右上腹压痛,无肌紧张及反跳痛,腹部未触及包块。 相似文献
110.
目的探讨组织切片对图像分析仪测量细胞核DNA含量的影响。方法选取10只成年健康雄性小鼠,制备肝细胞涂片和肝组织切片,肝组织切片分成两部分,分别用于Feulgen染色和石蜡包埋,包埋后的组织采用垂直切片,图像分析仪测量切片实际厚度,依据切片机标识厚度和测量厚度分别分组,TIGER细胞图像分析仪分别测量肝细胞涂片和组织切片内肝细胞核的积分光密度(IOD)。结果肝细胞涂片内各DNA含量倍体肝细胞核IOD间的比值接近2和4,IOD之变异系数(CV值)<3.5,肝组织切片IOD间比值明显偏离2和4,IOD之CV值均>6;切片机标识厚度为4、6、8和10μm组织切片平均测量厚度分别为6.75、7.18、6.96和7.59μm,测量厚度最大值为9.25μm,最小值为4.62μm;依据切片机标识厚度分组中不同切片厚度相同DNA含量倍体肝细胞核的IOD值差异均无统计学意义;依据测量厚度重新分组后5、6微米组与7、8、9微米组IOD值间的差异具有统计学意义(P<0.05)。结论组织切片的实际厚度与切片机标识厚度间存在明显差异,本实验方法可较准确地判断组织切片厚度;厚组织切片测量结果优于薄组织切片,但与细胞涂片相比,厚组织切片仍难... 相似文献