教学课程资源库 更多>>

关键词： embryogenesis   frozen storage   Larix   mature   seasonal effects  

摘要： Branches were collected in the winter and early spring from a 37-year-old Larix decidua and a L. x eurolepis tree. Part of these were used immediately and the rest stored at -5 degrees C and -10 degrees C for 3 months. Primordial shoot explants were excised from stored and non-stored material and cultured on half-strength Litvay medium free of growth regulators. Storage at -5 degrees C promoted formation of embryo-like structures which formed shoots with elongated stems (long-shoots). The highest number of these was obtained with material collected shortly before bud break. De-needled stem sections, cut from elongating stems in early summer, produced axillary short-shoots instead of embryo-like structures.

关键词： cell migration   cell differentiation   cerebellar cortex  

摘要： Few studies have been performed to evaluate the ultrastructural changes that exposure to static magnetic fields (SMF) can cause to the processes of cell migration and differentiation in the cerebellum during development. Thus, we have studied the development of the cerebellum in the chick embryo (n = 144) under a uniform SMF (20 mT). All of our observations were done on folium VIc of Larsell's classification. The cerebella of chick embryos, which were exposed solely on day 6 of incubation and sacrificed at day 13 of incubation [short exposure (S)1;n = 24], showed an external granular layer (EGL) that was less dense than the EGL in the control group (n = 24). The molecular layer (ML) exhibited a low number of migratory neuroblastic elements. Moreover, the internal granular layer (IGL) was immature, with the cellular elements less abundant and more dispersed than in controls. In chick embryos exposed on day 6 of incubation and sacrificed at day 17 (S2;n = 24), the outstanding feature was the regeneration of the different layers of the cerebellar cortex. The cerebellar cortex of chick embryos exposed continuously to an identical held from the beginning of the incubation up to day 13 [long exposure (L)1;n = 24] or day 17 (L2;n = 24) of incubation showed a higher number of alterations than that of group S1. Electron microscopy confirmed the findings from light microscopy and, at the same time, showed clear signs of cell degeneration and delay in the process of neuronal differentiation. This was more apparent in groups L1 (100%) and L2 (100%) than in groups S1 (95.4%) and S2 (65.2%). In conclusion, the present study showed that SMF can induce irreversible developmental effects on the processes of cell migration and differentiation of the chick cerebellar cortex. (C) 1997 Wiley-Liss, Inc.

关键词： 人体组织学   人体胚胎学   图谱  

ISBN: (纸本)7117026146

关键词： 声像图表现   宫内   子宫   女生殖器   组织残留   胚胎  

关键词： Embryonic and Fetal Development   Gene Expression Regulation   Developmental   Acetylcholine   Angiotensin II   Animals   Cell Membrane   Female   Gene Expression Regulation   Enzymologic   Glutamate Decarboxylase   Membrane Potentials   Mice   Neurons   Olfactory Bulb   Organ Culture Techniques   Patch-Clamp Techniques   Pregnancy   RNA   Messenger   Synapses   Vomeronasal Organ   gamma-Aminobutyric Acid  

摘要： In previous work, we showed a robust gamma-aminobutyric acid (GABAergic) synaptic input onto embryonic luteinizing hormone-releasing hormone (LHRH) neurons maintained in olfactory explants. In this study, we identify GABAergic neurons in olfactory pit (OF) of embryonic mice in vivo and study, using patch-pipet whole-cell current and voltage clamp techniques, synaptic interactions of these neurons in explant cultures. In vivo, glutamate decarboxylase (GAD, the enzyme which synthesizes GABA) mRNA was first detected in nasal regions on Embryonic Day (E) 11.5. From E12.5 to E13.5, robust GAD expression was localized to cells primarily in the ventral aspect of the OF. GAD mRNA was not detected over dorsally located cells in olfactory sensory or respiratory epithelium. In addition, GAD mRNA was not observed in cells along olfactory axons. GAD mRNA was dramatically reduced in the OP/vomeronasal organ by E16.5. Using antibodies against both GABA and GAD, immunopositive axonal-like tracts were detected in the nasal septum on E12.5. GABAergic staining decreased by E13.5. To examine synaptic interactions of these GABAergic cells, embryonic olfactory explants were generated and maintained in serum-free media. As explants spread, neuron-like cells migrated into the periphery, sometimes forming ganglion-like clusters. Cells were recorded, marked intracellularly with Lucifer Yellow and postfixation, immunocytochemically examined. forty-six cells, typically multipolar, were GABAergic, had resting potentials around -50 mV, and exhibited spontaneous action potentials which were generated by spontaneous depolarizing GABAergic (GABA(A)) synaptic activity. OP neurons depolarized in response to GABA by increasing Cl- conductance. The biophysical properties of OF-derived GABAergic neurons were distinct from those reported for olfactory receptor neurons but similar to embryonic LHRH neurons. However, unlike LHRH neurons, GABAergic neurons did not migrate large distances in olfactory explan

关键词： 形态学科   组织学与胚胎学   指导   方法   基本要求   优化教学   改革   提高教学质量   偏离   方向  

摘要： 教学原则是有效进行教学的基本要求．它既可指导教师的教，又能指导学生的学。所以．任何一种教学方法的改革都必须遵循教学规律．符合教学原则。否则，将会偏离方向．难以获得预期的教学效果。因此．只有在教学原则的指导下优化教学方法，才能提高教学质量，实现敦育目标。笔者经过多年的《组织学与胚胎学》教学实践，觉得下列教学原则与方法符合形态学科的教学实际。

关键词： 人胚胎   睾丸   生殖细胞   细胞发育   超微结构  

摘要： 用光镜与电镜技术,对15例7至28周人胚胎睾丸生殖细胞的发育进行了研究.结果:(1)据时间、位置及形态结构特点,将生殖细胞的发育过程初步分为三个阶段,即原始生殖细胞阶段,生殖母细胞阶段和前精原细胞阶段.其中前精原细胞阶段又经历了早、中、晚三个时期,各期出现的时间有交错.(2)14周是胚胎生殖细胞发育的一个重要时期.生殖细胞的增殖高峰、退化高峰以及前精原细胞初次出现均在此期.此期生殖细胞间还见到细胞连接,说明生殖细胞在胚胎时期即出现同步分化的现象.

关键词： 组织胚胎学   胚胎发育   化学梯度   分子信号