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ISBN: (纸本)7810712799

摘要： Recent studies have indicated that nitric oxide (NO)-induced cGMP synthesis is involved in different steps of neurogenesis in invertebrates. The development of putative NO synthetising elements was described earlier in the embryonic and juvenile pond snail, Lymnaea stagnalis, applying NADPH-diaphorase histochemistry (Serfozo et al., 1998). In the present study, we examined the distribution of NO synthase ( NOS) during Lymnaea development by in situ hybridization for Lymnaea-NOS mRNA, histochemical, and immunohistochemical techniques for the NOS and NO-stimulated cGMP. Peripheral fibers projecting to the CNS and terminating in the ganglionic neuropils showed NOS immunoreactivity from 85% of embryonic development. At the same time, a fine dot-like, immunostaining indicated the presence of cGMP in the neuropil area. In the CNS, Lymnaea-NOS mRNA positive, as well as NOS and cGMP immunoreactive perikarya were detected first during postembryonic development;their number significantly increased from P3 juvenile stage. Some of the cell groups in the CNS containing NOS immunoreactive material also displayed Lymnaea- NOS mRNA hybridization signal and were cGMP-positive. However, in the subesophageal ganglia, the distribution of Lymnaea- NOS mRNA positive cell groups did not correspond to that of the NOS immunoreactive cells. Neurons revealing transient NOS and cGMP immunoreactivity, respectively, could also be detected in this part of the CNS. In most of the ganglia the number of Lymnaea- NOS mRNA containing and cGMP immunopositive neurons, respectively, exceeded that of the NOS immunoreactive cells from P4 juvenile stage. The localization of NADPH-diaphorase reaction also correlated well with that of the NOS immunoreactivity in the developing CNS. At the periphery, colocalization of Lymnaea-NOS mRNA signal, NOS and cGMP immunoreactivities were observed in the epithelial cells of the esophagus and mantle after hatching. The findings suggest the functional maturity of the NO/c

关键词： 硫酸铝   胚胎   培养   谷胱甘肽   卵黄囊   膜流动性   膜脂质类   细胞膜  

摘要： 目的　为探讨铝的发育毒性及机理。方法孕 9.5d大鼠胚胎于体外培养系统中给予不同剂量的硫酸铝 ,培养 4 8h后 ,观察胚胎生长发育和器官形态分化状况 ;应用二硫代双硝基苯甲酸 (DTNB)直接法测定胚胎组织谷胱甘肽 (GSH)含量 ;以 1,6 二苯己三烯为荧光探剂 ,用荧光偏振技术测定卵黄囊细胞膜脂质流动性。结果　当培养液中铝浓度为1.2mg·L- 1时 ,胚胎生长发育和分化明显被抑制 ;3.0mg·L- 1时 ,畸形胚胎发生率明显升高 ,主要有神经管闭合不全 ,脑发育不良和体翻转不全 ;6 .0mg·L- 1时 ,胚胎组织GSH含量和卵黄囊细胞膜脂质流动性显著降低。上述效应均呈现出一定的剂量 效应 (反应 )关系。结论　铝有潜在的致畸性和胚胎毒性 。

关键词： 多媒体   组织胚胎学   医学教育  

摘要： 多媒体教学(计算机辅助教学)是80年代末期兴起的一种全新的教学模式,他以数字方式将表现学的教学内容和教学过程的图文、声像、动像画以及活动影像等信息通过计算机系统存储、加工、输出和呈现,用户可通过人要交互方式使用,以方便教师教、学生学.为此,我科于1999年引入多媒体教学.3年来,深深感受到了它的优点,也发现许多不足之处.

关键词： Xenopus laevis   homeobox genes   Gbx2   neural tube   midbrain/hindbrain boundary   embryonic development   gene regulation   gastrulation   neurula  

摘要： Development and differentiation of the vertebrate caudal midbrain and anterior hindbrain are dependent on the isthmic organizer signals at the midbrain/hindbrain boundary (MHB). The future MHB forms at the boundary between the Otx2 and Gbx2 expression domains. Recent studies in mice and chick suggested that the apposition of Otx2- and Gbx2-expressing cells is instrumental for the positioning and early induction of the MHB genetic cascade. We show that Otx2 and Gbx2 perform different roles in this process. We find that ectopically expressed Otx2 on its own can induce a substantial part of the MHB genetic network, namely En2, Wnt1, Pax-2, Fgf8 and Gbx2, in a concentration-dependent manner. This induction does not require protein synthesis and ends during neurulation. In contrast, Gbx2 is a negative regulator of Otx2 and the MHB genes, Based on the temporal patterns of expression of the genes involved, we propose that Otx2 might be the early inducer of the isthmic organizer genetic network while Gbx2 restricts Otx2 expression along the anterior-posterior axis and establishes an Otx2 gradient. (C) 2002 Elsevier Science Ltd. All rights reserved.

关键词： coagulation   gene targeting   tissue factor   factor VII   factor X   embryonic development   vasculogenesis  

摘要： Inactivation of specific genes in mammals by gene targeting has accelerated our ability to determine gene function. Nearly all genes involved in the blood coagulation system have been knocked out in mice, Tissue factor (TF) is the main initiator of the coagulation system and functions as a cell surface receptor for coagulation factor VII (FVII). Knockout studies have shown that TF deficiency results in lethality around embryonic day (E) 8.5-10.5. The results suggest a role for TF in embryonic blood vessel development and maintenance of vascular integrity in the yolk sac. In addition;TF may be involved in the maintenance of the placental labyrinth. Factor X (FX) deficiency causes partial embryonic lethality between E11.5-12.5. FX-/- mice that were born died from fatal neonatal bleeding. In contrast, FVII deficiency is not embryonic lethal, but FVII-/- neonates died from hemorrhage within the first days afterbirth. The various lethal phenotypes of deficiencies of the different coagulation factors suggest involvement in processes beyond hemostasis. Both TF/FVIIa and FXa can trigger intracellular signaling events in certain cell types. Signaling by coagulation proteases and protease-activated receptors (PARs) may have important roles in embryonic development.

关键词： light microscopy   transmission electron microscopy   scanning electron microscopy   duodenal anomaly   apoptosis  

摘要： Histogenesis of the duodenum, especially changes in the epithelium in relation to temporal occlusion and re-canalization of the lumen, was investigated by light microscopy together with morphometric analysis, as well as by scanning and transmission electron microscopy of 133 externally normal human embryos ranging from Carnegie stage 12 to 23. A series of morphogenetic events passed the duodenum in a cranio-caudal (proximo-distal) wave like fashion during the period examined. They included: (1) a decrease in the caliber and area of the lumen, (2) 'occlusion' of the lumen, (3) vacuole formation, (4) 're-canalization' and villi formation. The only exemption to this rule was that, in the upper part of the duodenum, the lumen was not obliterated in the embryos examined. Morphometric analyses revealed that both the area of the epithelium and the number of epithelial cells decreased during the 'occlusion' phase. This result suggests that, unlike the classical view, epithelial cell proliferation does not play an important role in occluding the lumen, but the predominant morphogenetic event during this phase is convergence of the epithelial cells to elongate the duodenum. Apoptosis, contrary to some classical views, decreased during the 're-canalization' phase, and it appeared to be involved in the formation of the small lumens in the epithelial 'plug' and in villi formation, but not in enlarging the secondary lumens. The secondary small lumens in the occluded lumen were frequently formed near the border between the central 'plug' and peripheral basal cells on the basement membrane. This and other findings of concentric differentiation in both the epithelial and mesenchymal layers suggested a possible control mechanism by the epithelium-mesenchymal interaction on human duodenal morphogenesis and histogenesis. The present electron microscopic observations also provided details on the mechanisms involved in the enlargement of the secondary lumen and differentiation of villi.

关键词： mouse   embryonic stem cells   embryoid bodies   vasculogenesis   hematopoiesis   myogenesis   endoderm  

摘要： We examined the histological structure of embryoid bodies arising from aggregation of mouse embryonic stem (ES D3) cells after 7, 12, 18 and 26 days of in vitro culture. Morphology of originally solid embryoid bodies was affected by the process of cavitation that resulted in formation of cystic embryoid bodies and by spontaneous differentiation of the ES D3 cells. We applied in situ immunophenotyping to characterise cell populations that spontaneously differentiated inside the embryoid bodies in the various stages. The most distinct cell populations that were found inside embryoid bodies were alpha-fetoprotein-positive endodermal cells and myogenic cells that expressed desmin, myogenin or smooth muscle actin. ES D3-derived endothelial cells generated during vasculogenesis inside the embryoid bodies differed from mature endothelial cells because they did not stain for von Willebrand factor. These cells also differed from endothelial cell that were generated during angiogenesis since they did not stain for the intermediate filament nestin. Our results demonstrate the usefulness of this in vitro model for studying early embryogenesis.

关键词： 解剖学报   细胞化学   房室结   教研室   人体解剖学   田原结   心脏传导系统   基础医学   组织学   组织胚胎学   海马神经元   大鼠海马   生物化学   组织化学   雌激素受体   神经型一氧化氮合酶   中心纤维体  

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关键词： 主题词：人体解剖学-医学院校-教材-人体组织学：人体胚胎学-医学院校-教材