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关键词： activity regulated cytoskeleton associated protein   patterning   visceral endoderm   gene expression   gene targeting   genomic organization  

摘要： Activity-regulated, cytoskeleton-associated protein (Arc) was first identified as an immediate-early gene regulated by synaptic activity. We have studied its functional role in vivo using a gene-targeting approach. We found that Arc is encoded by a single exon, and Arc mRNA is ubiquitously expressed in early mouse embryos. Homozygous Are mutants are severely growth-retarded, fail to gastrulate and subsequently die before day 8.5 of embryogenesis. Further analysis revealed severe disorganization of visceral endoderm formation, and total separation and ectopic location of embryonic and extraembryonic structure. These findings demonstrate that Are function is essential for early embryo development and patterning in mice, and support the hypothesis that signaling from visceral endoderm is essential for normal patterning of the extraembryonic and embryonic structure. (C) 2000 Elsevier Science Ireland Ltd. All rights reserved.

关键词： Animals   Apoptosis   Autoradiography   Base Sequence   DNA Primers   Dihydrotestosterone   In Situ Nick-End Labeling   In Vitro   Lung   Mice   Morphogenesis   Research Support   U.S. Gov't   P.H.S.   Thymidine  

摘要： Early gestation lung development is characterized by branching morphogenesis of the airways and basic lung structure formation. Androgens delay late-gestation lung development if the androgen exposure begins in early gestation. We hypothesized that there would be effects of early gestation androgens on lung development. Embryonic mouse lungs (d 11.5) were cultured with dihydrotestosterone (DHT), DHT plus flutamide, or with nothing as controls. Branching morphogenesis was significantly increased after 24, 48, and 72 h of culture. This effect was blocked by simultaneous flutamide treatment. Fetal sex did not influence the DHT response. DHT increased cell proliferation as measured by [H-3]thymidine incorporation into DNA. Autoradiography showed prominent [H-3]thymidine labeling of epithelia and mesenchyme in regions of new bud formation. DHT treatment significantly increased the thymidine-labeling index of fibroblasts and airway epithelial cells. Programmed cell death, which is found in developing organs in association with cell proliferation during structure formation and tissue remodeling, was studied using terminal deoxyribonucleotidyl transferase-mediated dUTP-digoxigenin nick end labeling assay. In control lungs, programmed cell death occurred in the peripheral mesenchyme surrounding newly forming buds and underlying airway branch points. DHT treatment increased programmed cell death in association with increased branching morphogenesis. Evaluation of near-adjacent sections (control and DHT-treated lungs) showed that apoptotic mesenchymal cells were flanked by [H-3]thymidine-labeled fibroblasts and epithelial cells, suggesting a coordination of these processes in the progression of branching morphogenesis. We conclude that androgen enhances the process of early lung morphogenesis by increasing cell proliferation and programmed cell death and by promoting the structural progression of branching morphogenesis.

关键词： Sox9   cartilage   chondrocyte   chondrogenesis   limb development   micromass culture   type II collagen  

摘要： Sox-9 plays a crucial role in chondrogenesis, It encodes an HMG-domain transcription factor that activates an enhancer in the gene for type II collagen (Col2a1), a principal cartilage matrix protein, We have characterized the temporal pattern of Sox9 RNA expression in micromass culture, a widely used in vitro model for the analysis of embryonic cartilage differentiation. Cultures were prepared from distal subridge mesenchyme of the stage 24/25 chick embryo wing bud, which undergoes uniform chondrogenic differentiation in vitro. The early "prechondrogenic" phase of culture was characterized by the activation of Sox9 RNA expression, which preceded detectable upregulation of Col2a1 transcription. Sox9 RNA levels peaked between 20 and 65 h of culture, a phase of progressive Col2a1 transcript accumulation, then declined in the mature cartilage of 120-h cultures, Staurosporine treatment enhanced chondrogenesis in micromass culture by inducing a rapid quantitative increase in Sox9 transcript levels. However, PMA, a phorbol ester that inhibits Col2a1 expression and chondrocyte differentiation, had an unexpectedly modest effect on Sox9 RNA accumulation. (C) 2000 Academic Press.

关键词： 气管   人胚胎   组织发生  

摘要： 目的 :了解气管壁的组织发生及探讨婴幼儿呼吸道疾病的相关因素。方法 :应用HE及PAS反应 ,光镜观察。结果 :8周的胚胎 ,气管壁由 2 3层复层柱状上皮细胞及外周的间充质构成 ,上皮细胞的PAS反应为阳性。 10周的胚胎 ,气管壁的上皮仍为复层柱状 ,上皮细胞的PAS反应弱阳性 ,外周间充质内出现少量点片状的透明软骨。12周时 ,在复层柱状上皮内出现纤毛细胞 ,上皮的PAS反应为阴性 ,间充质内透明软骨片增多。 14周气管壁可分出三层结构 ,粘膜上皮已变为假复层纤毛柱状 ,粘膜下层可见少量未分化的腺泡及导管 ,外膜透明软骨片继续增多并排列成“C”形 ,环缺口处的平滑肌出现。结论 :14周左右胎儿气管的三层结构初步建立 ,2 8周左右结构发育如成人。

关键词： 棉花   胚胎发生   直接诱导   植株再生   组织培养  

摘要： 选用我国主栽棉花 ( Gossypiumhirsutum L.)品种“中棉所 1 2”,首次直接诱导获得棉花体细胞胚胎发生 ,并获得了再生植株。结果表明 ,激素是影响棉花体细胞胚胎直接发生的重要因素 ,单独使用 ZT可直接诱导获得棉花胚性愈伤组织和胚状体 ,2 ,4 -D的添加虽有利于愈伤组织的形成 ,但却没能直接诱导获得胚性愈伤组织 :IAA的添加削弱了 ZT的诱导效果。下胚轴、子叶和胚根直接诱导获得胚胎发生的能力不同 ,其中以子叶的分化能力最强 ,胚根次之 ,下胚轴较差。在本实验中 ,棉花体细胞胚胎直接发生的最高频率为 1 1 .4 2 %,占诱导获得总愈伤组织的 4 4.4 4%。

关键词： 组织胚胎学   实验课   教学改革  

关键词： 组织胚胎学   实验课   组织准备   医学教育  

摘要： 从组织胚胎学实验课的组织、准备和实施 3个环节阐明认真制作组织切片 ,建立完整实验档案的重要性。做好课前准备 ,优化实验程序 ,精心组织实验教学 ,向课堂要效益。对强化实验管理意识 ,优化实验内容 。

关键词： .spreading   SURFACE TENSION   tensions   embryonic tissues   Kelvin model   viscoelastic properties  

摘要： Early embryonic development is characterized by spectacular morphogenetic processes such as sorting or spreading of tissues. Analogy between viscoelastic fluids and certain properties of embryonic tissues turned out to be useful in interpreting some aspects of these morphogenetic phenomena. In accordance with the differential adhesion hypothesis, the values of tissue-specific surface tensions have been shown to be consistent with thr equilibrium configurations such tissues reach in the course of sorting and spreading. A method to measure tissue surface tension and viscoelastic properties is described. Notions like the Laplace's equation relating surface tension to radii of curvature, or the Kelvin model of viscoelasticity are used to analyze the results of these measurements. The fluid analogy is extended to time-dependent phenomena, in particular, to the analysis of cellular pattern evolution in the course of spreading. On the basis of recent experimental findings, we demonstrate that the kinetics of spreading and nucleation in binary fluids can be analyzed using the same formalism. We illustrate how our results can be used to obtain biologically relevant information on the strength of binding between specific cell adhesion molecules under near physiological conditions. We also suggest a diagnostic application of our method to monitor the metastatic potential of tumors.

关键词： Parkinson's disease   animal models   allografts   positron emission tomography (PET)  

摘要： A multicenter study is under way to investigate the efficacy of allografting of embryonic mesencephalic neurons in a pig model of Parkinson's disease. We have first established that a stable parkinsonian syndrome can be established by 1-methyl-4-phenyl-1,2,3,6-tetrahydropyridine (MPTP) intoxication of adult male Gottingen minipigs. We are now using positron emission tomography (PET) methods for testing the physiological responses to MPTP intoxication and the time course of the response to several treatment strategies. We now report preliminary results obtained in 11 pigs employed in the initial phase of the study;the completed study shall ultimately include 30 pigs. Animals were randomly assigned to one of five groups: 1) Control, 2) MPTP intoxication, 3) MPTP intoxication followed by allograft, 4) MPTP intoxication followed by allograft with immunosuppression, and 5) MPTP intoxication followed by allograft with immunosuppression acid co-grafting of immoratized HiB5 cells, which had been manipulated to secrete glia cell line-derived neurotrophic factor (GDNF) (approximate to 2 ng GDNF/h/10(5) cells). MPTP was administered (1 mg/kg/day, SC) for 7-10 days until the pigs had developed mild parkinsonian symptoms of muscle rigidity, hypokinesia, and impaired coordination, especially of the hind limbs. Approximately 2 weeks after the last MPTP dose, animals received a T1-weighted magnetic resonance imaging (MRI) scan, and a series of dynamic PET recordings, After the First series of PET scans, four grafts of porcine embryonic mesencephalic tissue (E28 days) were placed in each striatum of some MPTP-intoxicated pigs, using MRI-based stereotactic techniques. Immunosuppression of some animals with cyclosporin and prednisolone began just prior to surgery. Two more series of PET scans were performed at 4-month intervals after surgery. After the last scans, pigs were killed and the blains were perfused for unbiased stereological examination of cytological and histochemical mark

关键词： lung   chick embryo   oligosaccharides   lectins  

摘要： A lectin histochemical study was performed to investigate the distribution and changes of the oligosaccharidic component of the glycoconjugates in the lung of chick embryos, of 1-day-old chick, and of the adult animal. For this purpose, a battery of seven horseradish peroxidase-conjugated lectins (PNA, SEA, DBA, WGA, Con A, LTA, and UEA I) were employed. During the first phase of parabronchi and atria formation, D-galactose-(beta->3)-N-acetyl D-galactosamine, beta-N-acetyl-D-galactosamine, D-glucosamine, alpha-D-mannose, and sialic acid, present at the level of the surface and of cytoplasmic granules of the lining epithelial cells, seem to play a role in regulating morphogenetic phenomena. In the subsequent phases, the parabronchial lumen and the atrial cavities were characterized by the presence of lectin-reactive material rich in terminal D-galactose-(beta 1->3)-N-acetyl-D-galactosamine, beta-N-acetyl-D-galactosamine, D-glucosamine and alpha-D-mannose. From day 18 onwards and immediately after hatching, the free border of the cells Lining the air capillaries was characterized by the presence of beta-N-acetyl-D-galactosamine and alpha-D-mannose. The appearance of these sugar residues was concomitant with the beginning of respiratory activity. (C) 2000 Wiley-Liss, Inc.