胎儿气管发育的组织学观察

本文取４～１０月龄胎儿气管作横切片，经Ｈ．Ｅ．染色，在显微镜下观察其粘膜上皮的类型、透明软骨细胞和腺泡的发育．结果发现：（１）４～６月龄胎儿的气管粘膜上皮为单层纤毛柱状上皮，８～１０月龄胎儿的为假复层纤毛柱状上皮．（２）随着胎龄的增长，软骨细胞的体积增大，短径增大较快；细胞密度减少；腺泡数量增加．这些变化在７～８月龄间发生较快．     

胎儿胃腺壁细胞发育的体视学研究

应用体视学方法对３４例不同月龄的人工引产胎儿及死胎胃标本进行胃腺壁细胞定量研究，结果显示胎儿胃腺壁细胞体密度（Ｖｖ）、表面积密度（Ｓｖ）、数密度（Ｎｖ）均随着胎儿的发育而增加．核体密度（Ｖｖｍ．ｃ）则随着胎儿发育而变小．     

麻雀视网膜的组织学研究

为了研究麻雀(PAsser montanus)视网膜与其白昼活动的关系，以常见麻雀视网膜为材料，用组织学方法进行某些定量研究，并观察其结构．观察结果表明：麻雀视网膜中有大量的视锥细胞，视锥细胞分为单锥(SC)和双锥(DC)两大类，视细胞在中央区较多，在周边区较少，视锥与视杆比为9．2：1，视细胞与神经节细胞比为5：1,视网膜中视神经节细胞的密度、直径及排列方式随距离中央区的远近而变化．     

利用Monte Carlo算法对薄膜生长过程的计算机模拟

用Monte Carlo方法以Cu为例对薄膜生长过程进行计算机模拟．不仅对原子的吸附、迁移及脱附3种过程采用更为合理的模型，还考虑这些过程发生时对近邻原子的连带效应．在合理选择原子间相互作用势计算方法的基础上．改进了原子迁移激活能的计算方法．计算了表征薄膜生长表面形貌的表面粗糙度和表征薄膜内部晶格完整性的相对密度．结果表明，在一定的原子入射率下，表面粗糙度和相对密度的变化存在一个临界温度．随着衬底温度的升高．表面粗糙度减小，膜的相对密度增大．当达到临界温度时，粗糙度随衬底温度的升高开始增大，而相对密度趋于饱和．临界温度随原子入射率的增大而增大，不同温度下原子入射率对粗糙度的影响不同，在较低温度时粗糙度随入射率的增加而增加，在较高温度时粗糙度随入射率增大而减小．同时发现．随入射率的增大或薄膜厚度的增加，相对密度均逐渐减小。     

低频液体表面张力与频率关系研究

研究了低频液体在不同频率下表面张力的变化特性．计算出蒸馏水在19～30Hz频率范围的动表面张力，给出了不同频率下的表面张力与频率关系曲线．结果表明，表面张力随频率的增长呈非线性增大，且增大幅度逐渐减小．     

小鼠视网膜胆碱能无长突细胞出生后的密度分析

为了研究小鼠出生后视网膜胆碱能无长突细胞密度和空间分布的发育变化,使用免疫组织化学的方法对不同天龄小鼠视网膜的胆碱能无长突细胞进行免疫荧光标记,并对用激光共聚焦显微镜采集的数据进行统计学分析.结果表明,小鼠视网膜胆碱能无长突细胞的密度随天龄增长而降低,这个结果与通过眼球直径预测的变化一致.     

β－内啡肽能神经元系统在雌性大鼠视前区的增龄变化

用ＡＢＣ法免疫组化技术结合体视学分析，对青年组（３月龄）、中年组（１０～１２月龄）及老年组（２４～３０月龄）雌性大鼠视前区β－内啡肽能神经元系统进行研究。结果显示：室周核、内、外侧视前区各部位β－内啡肽能神经元胞体数量随增龄均无丢失；而上述三部位内β－内啡肽能神经纤维密度至中年组皆已降低，至老年组下降更为明显。实验表明β－内啡肽能神经元系统在雌性大鼠视前区随增龄发生了不均一性变化。     

乌孜别克族成人围度值的年龄变化

测量了201例乌孜别克族成人的头水平围、胸围、腹围、臀围、上臂围、前臂围、上臂最大围、大腿围、小腿围的围度值，分年龄组研究了随年龄增长的9项围度值的变化状况，进行了男女间围度的比较，并与我国其他人群的围度值进行了比较．结果发现：（1）随年龄的增长，男性与女性的躯干围度呈明显增加趋势．（2）四肢围度值呈先上升后下降的趋势，最大值在40-岁组．（3）男性在40-岁组，女性在50-岁组头水平围值最大．（4）随年龄的增长，躯干围度值变化范围明显大于四肢围度值变化范围，而头水平围值变化很小．（5）除大腿围外，男性其余8项围度值大于女性．50岁后，女性腹围值超过男性．（6）随年龄增长，除小腿围外，女性其余8项围度值增加的绝对值与相对值均大于男性，男女围度的差值随年龄增长而逐渐缩小．（7）聚类分析显示，乌孜别克族围度值与柯尔克孜族最接近．我国16个人群围度比较，表明乌孜别克族围度值较大．     

林分密度对南方型杨树木材性质的影响

就林分密度对南方型杨树材性的影响进行研究。研究结果表明：①林分密度对各无性系木材的纤维素含量影响规律不明显；②随林分密度增大，纤维长度有所增长，各级纤维频率趋于均匀，林分密度对纤维宽度与长宽比影响不显著；③林分密度对Ｓ_２层微纤丝角有显著影响，Ｓ_２层微纤丝角随着林分密度的增大而减少；④木材相对结晶度随林分密度的增大而增大；⑤随着林分密度的增大，木材的冲击韧性降低，而气干密度逐渐增大。在４ｍ×４ｍ、５ｍ×５ｍ和６ｍ×６ｍ株行距的林分中，随林分密度增加其抗弯强度和弹性模量增大。而对木材的抗压强度影响不明显。     

石灰改良红黏土导热系数影响因素及模型预测

导热系数是研究温度场的重要参数,基于石灰与红黏土酸碱互损随时间的演化,利用瞬态热线法导热系数仪,研究含水率、干密度以及龄期对石灰改良红黏土导热系数的影响,并建立经 验函数和BP神经网络预测模型。结果表明：石灰改良红黏土的导热系数随含水率的增加呈指数增长,随干密度的增加呈线性增长;在15-27%含水率范围内,其导热系数平均增长53.87%;在1.25-1.65 g·cm?3干密度范围内,其导热系数平均增长87.06%;改良土导热系数随龄期的增加呈指数降低,降低速率逐渐减小,最终有趋于稳定的趋势,在龄期90 d范围内,导热系数平均降低16.6%。经验证分析,两种模型的整体误差均小于10%;可以很好的描述石灰改良红黏土的导热系数随影响因素的变化情况。该规律以及模型,可以为日后相同土样进行石灰改良提供参考。     

海洛因对小脑皮质Bax表达的影响

目的 探索海洛因对小脑皮质Bax蛋白（bcl-x protein Bax）表达的影响.方法 肌肉注射海洛因,建立成瘾大鼠模型,用免疫组化方法检测小脑细胞Bax的表达.结果 连续给大鼠注射海洛因7d后,大鼠出现明显的戒断症状;小脑细胞中Bax表达阳性细胞比对照组明显增多,与对照组比有显著性差异（P＜0.01）.结论 海洛因具有诱导Bax基因表达、损伤脑组织细胞的作用.     

Differential inhibition of neurone-neurone, neurone-astrocyte and astrocyte-astrocyte adhesion by L1, L2 and N-CAM antibodies

The cell adhesion molecules L1, N-CAM and Ng-CAM have been implicated in cell-cell interactions among developing neural cells. L1 and N-CAM are structurally and functionally distinct molecular entities and act synergistically in mediating Ca2+-independent adhesion between re-aggregating early postnatal cerebellar cells. N-CAM has been reported to be neurone-specific in the chicken and to mediate fasciculation of neurites and of nerve-muscle interactions. L1, which in the central nervous system has been found only on post-mitotic neurones, mediates migration of granule cell neurones in the mouse cerebellar cortex. In view of the molecules' distinct effects on cell interactions, we wondered whether different neural cell types are involved in the actions of each molecule. Here we report that L1 antigen promotes neurone-neurone adhesion. N-CAM, which is expressed on both neurones and glia, mediates neurone-neurone, neurone-astrocyte and astrocyte-astrocyte adhesion. The L2 carbohydrate epitope shared between the two adhesion molecules seems to be involved in neurone-astrocyte and astrocyte-astrocyte adhesion and acts in a more than additive manner in N-CAM-mediated neurone-neurone adhesion.     

L1 mono- and polyclonal antibodies modify cell migration in early postnatal mouse cerebellum

A major event of nervous system development is the migration of granule cell neurones, during the early postnatal development of the cerebellar cortex, from their germinating zone in the external granular layer to their final location in the internal granular layer. During migration, many granule cells are seen in direct cell-surface contact with processes of Bergmann glia, a subclass of astrocytes. In the neurological mutant mouse weaver, however, migration of granule cells is impaired, probably due to a deficit in cell-cell interactions. To gain insight into the cellular and molecular mechanisms involved in granule cell migration, we have used a modification of an in vitro assay system, previously described by Moonen et al., which displays migratory behaviour in small tissue explants during several days of suspension culture. The aim of this study was to investigate the process of granule cell migration by using antibodies directed against cell-surface components of developing neural cells. We report here that migration of 3H-thymidine-labelled granule cell neurones can be modified by Fab fragments of both mono- and polyclonal L1 antibodies, but not by Fab fragments of polyclonal antibodies prepared against mouse liver membranes, which also react with cerebellar cell surfaces.     

Neural cell adhesion molecules and myelin-associated glycoprotein share a common carbohydrate moiety recognized by monoclonal antibodies L2 and HNK-1

Cell surface molecules have been implicated in cell interactions which underlie formation of the nervous system. The analysis of the functional properties of such molecules has profited from the combined use of antibodies and cell culture systems. It has been suggested that the interplay between these molecules modulates cell-to-cell interaction at critical developmental stages. In the mouse, N-CAM and L1 antigen have been shown to mediate Ca2+-independent adhesion among neural cells. N-CAM plays a role in fasciculation of neurites and formation of neuromuscular junction. L1 is apparently not involved in synaptogenesis, but in migration of granule cell neurones in the developing mouse cerebellar cortex. The two antigens are distinct molecular and functional entities which act synergistically in aggregation of neuroblastoma and early postnatal cerebellar cells. In view of a certain similarity in function between the two groups of molecules, it was not surprising to find that structural similarities are detectable by the monoclonal antibody L2. We show here that a carbohydrate moiety recognized by L2 and HNK-1 monoclonal antibodies, is present in mouse N-CAM and L1. The L2 epitope appears on all major neural cell types but not all N-CAM molecules express it. This heterogeneity points to a previously undetected molecular diversity which may have functional implications for modulating cell adhesion during development.     

大鼠大脑中动脉供血区梗死后小脑皮质GFAP mRNA动态表达

采用Longa大鼠大脑中动脉内栓线阻断法制备动物模型,用实时定量PCR法检测大鼠大脑中动脉闭塞后小脑皮质胶质纤维酸性蛋白mRNA的表达。结果显示,持续性大鼠大脑中动脉闭塞后,胶质纤维酸性蛋白mRNA在大鼠的小脑皮层有动态表达,第1天、第3天和第5天比对照组明显增高(P0.05),第7天、第10天和第14天比对照组明显下降(P0.05)。大鼠大脑中动脉闭塞后小脑皮质出现胶质纤维酸性蛋白动态表达,远离梗死灶的相关部位脑组织继发损害机制可能与神经抑制因子有关。     

Neurolinguistics: structural plasticity in the bilingual brain

Humans have a unique ability to learn more than one language--a skill that is thought to be mediated by functional (rather than structural) plastic changes in the brain. Here we show that learning a second language increases the density of grey matter in the left inferior parietal cortex and that the degree of structural reorganization in this region is modulated by the proficiency attained and the age at acquisition. This relation between grey-matter density and performance may represent a general principle of brain organization.     

Cortical magnification factor and the ganglion cell density of the primate retina

It has long been contentious whether the large representation of the fovea in the primate visual cortex (V1) indicates a selective magnification of this part of the retina, or whether it merely reflects the density of retinal ganglion cells. The measurement of the retinal ganglion-cell density is complicated by lateral displacements of cells around the fovea and the presence of displaced amacrine cells in the ganglion cell layer. We have now identified displaced amacrine cells by GABA immunohistochemistry and by retrograde degeneration of ganglion cells. By reconstructing the fovea from serial sections, we were able to compare the densities of cones, cone pedicles and ganglion cells; in this way we found that there are more than three ganglion cells per foveal cone. Between the central and the peripheral retina, the ganglion cell density changes by a factor of 1,000-2,000, which is within the range of estimates of the cortical magnification factor. There is therefore no need to postulate a selective magnification of the fovea in the geniculate and/or the visual cortex.     

Purkinje neuron synchrony elicits time-locked spiking in the cerebellar nuclei

An unusual feature of the cerebellar cortex is that its output neurons, Purkinje cells, release GABA (γ-aminobutyric acid). Their high intrinsic firing rates (50?Hz) and extensive convergence predict that their target neurons in the cerebellar nuclei would be largely inhibited unless Purkinje cells pause their spiking, yet Purkinje and nuclear neuron firing rates do not always vary inversely. One indication of how these synapses transmit information is that populations of Purkinje neurons synchronize their spikes during cerebellar behaviours. If nuclear neurons respond to Purkinje synchrony, they may encode signals from subsets of inhibitory inputs. Here we show in weanling and adult mice that nuclear neurons transmit the timing of synchronous Purkinje afferent spikes, owing to modest Purkinje-to-nuclear convergence ratios (～40:1), fast inhibitory postsynaptic current kinetics (τ(decay) = 2.5?ms) and high intrinsic firing rates (～90?Hz). In vitro, dynamically clamped asynchronous inhibitory postsynaptic potentials mimicking Purkinje afferents suppress nuclear cell spiking, whereas synchronous inhibitory postsynaptic potentials entrain nuclear cell spiking. With partial synchrony, nuclear neurons time-lock their spikes to the synchronous subpopulation of inputs, even when only 2 out of 40 afferents synchronize. In vivo, nuclear neurons reliably phase-lock to regular trains of molecular layer stimulation. Thus, cerebellar nuclear neurons can preferentially relay the spike timing of synchronized Purkinje cells to downstream premotor areas.     

Thymus medulla consisting of epithelial islets each derived from a single progenitor.

The thymus is organized into medullary and cortical zones that support distinct stages of T-cell development. The formation of medulla and cortex compartments is thought to occur through invagination of an endodermal epithelial sheet into an ectodermal one at the third pharyngeal pouch and cleft, respectively. Epithelial stem/progenitor cells have been proposed to be involved in thymus development, but evidence for their existence has been elusive. We have constructed chimaeric mice by injecting embryonic stem (ES) cells into blastocysts using ES cells and blastocysts differing in their major histocompatibility complex (MHC) type. Here we show that the MHC class-II-positive medullary epithelium in these chimaeras is composed of cell clusters, most of which derive from either embryonic stem cell or blastocyst, but not mixed, origin. Thus, the medulla comprises individual epithelial 'islets' each arising from a single progenitor. One thymic lobe has about 300 medullary areas that originate from as few as 900 progenitors. Islet formation can be recapitulated after implantation of 'reaggregated fetal thymic organs' into mice, which shows that medullary 'stem' cells retain their potential until at least day 16.5 in fetal development. Thus, medulla-cortex compartmentalization is established by formation of medullary islets from single progenitors.