THE DISTINCT STEPS OF CELL DETACHMENT DURING DEVELOPMENT OF MOUSE UROEPITHELIAL CELLS IN THE BLADDER

In developing mouse urinary bladder the urothelial cells respond to urine accumulation by cell detachment, i.e. desquamation. To elucidate the steps of urothelial cell detachment during embryonic development and first urine accumulation in bladder lumen, superficial and intermediate cell layers were investigated. Different electron microscopic and cytochemical methods have been used. It was possible to distinguish between an early and late events on the basis of morphology. At the beginning cell detachment involves interruption of tight junctions between neighbouring superficial cells and the formation of numerous endocytotic vesicles. Endocytotic and cup-shaped vesicles then fuse and form large parallel rows of vacuoles and multivesicular bodies in desquamating superficial cells and in the neighbouring superficial and intermediate cells. These observations clearly demonstrate the existence of specific steps during the detachment of embryonic uroepithelial cells. Apoptosis accompanies cell desquamation. Only predetermined superficial bridge cells die in an apoptotic manner.     

THE FINE STRUCTURE OF THE GALL BLADDER EPITHELIUM OF THE MOUSE

Sections of mouse gall bladder epithelium fixed by perfusion with buffered osmium tetroxide have been studied in the electron microscope as an example of simple columnar epithelium. The free surface presents many microvilli, each presenting a dense tip, the capitulum, and displaying a radiating corona of delicate filaments, the antennulae microvillares. Very small pit-like depressions, representing caveolae intracellulares, are encountered along the cell membrane of the microvilli. The free cell surface between microvilli shows larger cave-like depressions, likewise representing caveolae intracellulares, containing a dense material. The lateral cell borders are extensively folded into pleats, which do not interdigitate extensively with corresponding folds of the adjacent cell membrane. The terminal bars are shown to consist of thickened densities of the cell membrane itself in the region of insertion of the lateral cell wall with the free cell surface. This thickening is associated with an accumulation of dense cytoplasmic material in the immediate vicinity. The terminal bar is thus largely a cytoplasmic and cell membrane structure, rather than being primarily intercellular in nature. The basal cell membrane is relatively straight except for a conical eminence near the center of the cell, projecting slightly into the underlying tunica propria. The basal cell membrane itself is overlain by a delicate limiting membrane, which does not follow the lateral contours of the cell. Unmyelinated intercellular nerve terminals with synaptic vesicles have been encountered between the lateral walls of epithelial cells. A division of the gall bladder epithelial cell into five zones according to Ferner has been found to be convenient for this study. The following cytoplasmic components have been noted, and their distribution and appearance described: dense absorption granules, mitochondria, Golgi or agranular membranes, endoplasmic reticulum or ergastoplasm, ring figures, and irregular dense bodies, perhaps lipoid in nature. The nucleus of these cells is also described.     

小鼠膀胱上皮的中间层细胞中存在Uroplakins

本文运用超薄切片、冰冻蚀刻及免疫胶体金标记等多种电镜技术并结合免疫组化、免疫荧光染色技术,直观地显示出小鼠膀胱上皮的中间层细胞存在Uroplakins,并在梭形泡膜上形成了与表层细胞类似的AUM结构,而且梭形泡的AUM结构也结合在中间纤维上。蛋白质免疫印迹反应进一步证实中间层细胞含有与表层细胞相同的Uroplakin Ⅰ和UroplakinⅢ等AUM蛋白的主要成份,从而为AUM的发生及其与细胞分化关系的研究提供了重要的实验证据。     

小鼠胚胎干细胞定向分化为神经干细胞过程中microRNA的变化

目的用生物芯片技术分析胚胎干细胞定向分化为神经干细胞过程中microRNA(miRNA)的表达变化,筛选调控的分化的miRNA,研究分化调控机制。方法胚胎干细胞在含LIF培养基中培养3d后,采用经典5步培养方法定向诱导向神经干细胞分化,采用nestin作为神经干细胞标记进行鉴定,送检胚胎干细胞及神经干细胞,提取总RNA以及小分子RNA,经荧光标记后与miRNA基因芯片杂交,获得胚胎干细胞诱导前后miRNA表达谱。结果1)胚胎干细胞在含LIF培养过程中保持未分化状态,Oct-4、碱性磷酸酶表达阳性;2)经典五步法诱导胚胎干细胞定向分化为神经干细胞,nestin阳性细胞为85%;3)通过基因微阵列分析,有90个miRNA的改变显著,其中68个表达上调,22个表达下调。结论miRNA可能对胚胎干细胞定向分化为神经干细胞过程起到关键作用。     

去神经后小鼠骨胳肌胞纳的增加和卫星细胞增殖

用生物化学和体外培养法研究了小鼠骨胳肌的胞纳增加和卫星细胞增殖的关系。结果表明：（１）去神经４ｄ或６ｄ的肌肉可引起胞纳的增和卫星细胞的增殖;（２）放线菌素Ｄ抑制正常肌肉的卫星细胞激活和胞纳作用;（３）在去神经的肌肉中,放线菌素Ｄ抑制了卫星细胞增殖的同时还抑制了胞纳的增加,但不能去神经肌肉的萎缩。上述结果：肌肉的卫星细胞增殖和胞纳增加可能发生于去神经后某些因素的出现,或者胞纳的增加即是卫星细胞增殖的     

ELECTRON MICROSCOPY OF ABSORPTION OF TRACER MATERIALS BY TOAD URINARY BLADDER EPITHELIUM

The absorption of Thorotrast and saccharated iron oxide by the epithelium of the toad urinary bladder was studied by electron microscopy. Whether the toads were hydrated, dehydrated, or given Pitressin, no significant differences in transport of colloidal particles by epithelial cells were observed. This implies that these physiological factors had little effect on the transport of the tracer particles. Tracer particles were encountered in three types of epithelial cells which line the bladder lumen, but most frequently in the mitochondria-rich cells. Tracer materials were incorporated into the cytoplasm of epithelial cells after being adsorbed to the coating layer covering the luminal surface of the cells. In the intermediate stage (1 to 3 hours after introducing tracer) particles were present in small vesicles, tubules, and multivesicular bodies. In the later stages (up to 65 hours), the particles were more commonly seen to be densely packed within large membrane-bounded bodies which were often found near the Golgi region. These large bodies probably were formed by the fusion of small vesicles. Irrespective of the stages of absorption, no particles were found in the intercellular spaces or in the submucosa. Particles apparently did not penetrate the intercellular spaces of the epithelium beyond the level of the tight junction.     

神经干细胞定向分化过程中溶酶体表达变化的研究

目的对神经干细胞向神经元定向分化过程中溶酶体的表达变化进行观察研究。方法采用细胞培养技术、荧光免疫细胞化学技术以及光电镜酶细胞化学技术对神经干细胞向神经元定向分化过程中溶酶体的表达变化进行观察。结果在神经干细胞向神经元定向分化的过程中,随着细胞分化的不断成熟,溶酶体的表达亦发生着变化。分化初期主要以核周附近表达明显,至神经元分化成熟则散在分布于胞质中及突起内,且表现有圆形、线状两种形态。结论在神经干细胞向神经元定向分化过程中溶酶体发生表达分布的变化,说明其参与了细胞的代谢和细胞内物质的运输。     

胚胎及生后不同发育时期大鼠睾丸生殖细胞的凋亡

目的 探索雄性生殖细胞在发育过程中凋亡的特征和规律。方法 利用改进的石蜡切片原位末端标记法（TUNEL法）观察SD大鼠睾丸生殖细胞,对胚胎及生后不同阶段生殖细胞凋亡进行研究。结果 胚胎第13.5天原始生殖细胞即有较高的凋亡率,胚胎第19.5天到出生后第1天,未检测到凋亡生殖细胞,出生后第7天精原细胞分裂增生,伴有较高的凋亡率,与其他各年龄组有显著性差异。出生后第14天精母细胞凋亡率最高,与其他日龄组有显著性差异。结论 SD大鼠雄性生殖细胞发生,发育,成熟过程中都存在凋亡,主要发生在处于细胞增殖过程中的原始生殖细胞,精原细胞和初级精母细胞。     

黄鳝膀胱上皮表面结构的电镜观察

应用电子显微镜观察了黄鳝膀胱上皮表面结构。发现其膀胱上皮表面具有许多平行排列的黏膜纵褶和褶间沟,它们的表面具大量微嵴,这些微嵴排列成指纹状结构;微嵴分为边嵴和中央嵴,其断面呈短指状;上皮表层细胞的顶面形态为近六边形。它们的界限是边嵴;边嵴间存在着一些呈椭圆形的微孔;在微孔下方发现一类含许多松仁。     

高尔基体在人胃腺癌细胞诱导分化过程中的变化

MGc 80-3细胞高尔基体呈发育差、结构不典型状态,但经dBcAMP诱导后,细胞内高尔基体组数增多、分布集中、体积增大,高尔基囊数目增多、排列规则,囊的膜内颗粒增多、分布较为均匀,恢复为与其相应正常细胞相似、发育良好的典型高尔基体结构。这种变化不仅抑制了胃癌细胞的恶性分泌活动,同时对细胞表面成份的变化也起着一定的调节作用。认为高尔基体结构与功能向典型方向的转??变是癌细胞恶性表型逆转的一种重要表现,对于癌细胞由恶性向正常方向的分化具有重要影响。     

CENTRIOLE MORPHOGENESIS IN DEVELOPING CILIATED EPITHELIUM OF THE MOUSE OVIDUCT

The differentiating mouse oviduct has been used for the study of centriole morphogenesis because its epithelium is extensively ciliated and centriole formation occurs in a brief period after birth. Proliferative elements, consisting of an extensive fibrillar meshwork encrusted with 75 mµ granules, were encountered at all ages, but were the only centriole precursors present in younger animals (2–3 days). These large aggregates were found either physically associated with a mature centriole or alone, but never associated with procentrioles. It is likely, therefore, that although proliferative elements may be derived from preexisting centrioles, they do not directly produce new centrioles. An intermediate structure, the condensation form, found primarily in older animals (4–6 days), and produced by the packing of the proliferative element material, gives rise to daughter procentrioles. This association of procentriole and condensation form has been called a generative complex. Condensation forms undergo various stages of depletion, producing hollow spheres with thin walls or small osmiophilic aggregates as procentrioles grow in length and assemble their microtubules. From these observations it is concluded that synthesis of microtubular precursor protein is mediated by the mature centriole and that this protein is packaged into many condensation forms in order to allow the rapid assembly of a large number of centrioles in a brief period of time.     

VIABILITY OF THE CERVICAL EPITHELIUM DURING CARCINOGENESIS IN MICE

Autoradiograms of histological specimens from the cervix of seventy-five mice were analysed after in vivo injection with an RNA precursor. All nucleated, non-pyknotic cells and some mitotic figures were labelled, which suggested that the tissue was metabolically active (i.e. viable). Only the uppermost epithelial pyknotic cells were devitalized, as deduced by the morphological appearance of the cells and by the absence of label. The viability of the whole epithelium suggests that the previously reported focal distribution of proliferating and non-proliferating areas in the cervical epithelium of mice is a genuine phenomenon.     

CHANGES IN THE SARCOPLASMIC RETICULUM AND TRANSVERSE TUBULAR SYSTEM OF FAST AND SLOW SKELETAL MUSCLES OF THE MOUSE DURING POSTNATAL DEVELOPMENT

The sarcoplasmic reticulum (SR) and transverse tubular system (TTS) of a fast-twitch muscle (extensor digitorum longus-EDL) and a slow-twitch muscle (soleus-SOL) of the mouse were examined during postnatal development. Muscles of animals newborn to 60 days old were fixed in glutaraldehyde and osmium tetroxide and examined with an electron microscope. At birth the few T tubules were often oriented longitudinally, but at the age of 10 days most of them had a transverse orientation. In the EDL, the estimated volume of the TTS increased from 0.08% at birth to 0.4% in the adult; corresponding values for the SOL were 0.04% at birth and 0.22% in the adult. A similar relative change was observed in surface area of the TTS during development. Calculated on the basis of a 30 µm diameter fiber, the surface area of the TTS in the EDL increased from 0.60 cm² TTS/cm² fiber surface in the newborn to 3.1 cm²/cm² in the adult, compared with 0.15 cm²/cm² at birth to 1.80 cm²/cm² in the adult for the SOL. The SR in the newborn muscles occurred as a loose network of tubules that developed rapidly within the subsequent 20 days, especially at the I band level. The volume of the SR increased in the EDL from 1.1% of fiber volume at birth to 5.5% in the adult. In the SOL the change was from 1.7% to 2.9%. The SOL approached the adult values more rapidly than the EDL, although the EDL had more SR and T tubules. Fibers of both EDL and SOL muscles showed variation in Z line thickness, mitochondrial content, and diameter, but over-all differences between the two muscles in amount of SR and TTS were significant. It is considered that the differing amounts of SR and TTS are closely related to the differing speeds of contraction that have been demonstrated for these two muscles.     

RNA METABOLISM IN ISOLATED MOUSE BRAIN NUCLEI DURING EARLY POSTNATAL DEVELOPMENT

—RNA metabolism in isolated brain nuclei has been shown to be dramatically altered during early postnatal brain development. The present study involved an examination of the RNA products synthesized by nuclei at various stages of postnatal neural maturation. In all cases, the majority of the RNA appeared to be heterodisperse, non-ribosomal and non-tRNA in nature. In comparison to the RNA isolated from nuclei of neonatal tissue, the RNA from nuclei of 12-day and 30-day-old mouse brain was found to be of smaller molecular weight. Despite the heterodisperse nature of these RNA molecules, the addition of α-amanitin did not completely inhibit nuclear synthesis. An investigation of RNA synthesis in isolated neuronal and glial cell nuclei revealed that nucleic acid metabolism in these respective cell populations had different and distinct developmental patterns. Preparations enriched with glial cell nuclei were found to be most active at birth and then decreased in activity (3–4-fold) during neural maturation. On the other hand, the rate of RNA synthesis in fractions enriched in neuronal cell nuclei was observed to increase dramatically in activity (4–5-fold) until 14 days of age. From 14 days of age until adulthood, RNA synthetic activity remained essentially the same.     

PROTEIN PROFILES OF RAT EMBRYO CEREBRAL CELLS DURING DIFFERENTIATION IN CULTURE

The protein composition of the particulate fraction of dissociated foetal rat cerebral cells during maturation in culture was investigated. SDS polyacrylamide gel electrophoresis showed a general decrease in the histonal components and significant changes in composition of a group of polypeptides with molecular weights ranging from 42 to 60 K. Two of these polypeptides coelectrophoresed with tubulin and actin whereas a 48 K polypeptide comigrated with the major component of the Wolfgram myelin protein. Its relative quantity appeared to approach a plateau after 8 days in culture. The myelin basic and proteolipid proteins were below detection levels in cultured cells at any time point investigated. A group of polypeptides with estimated molecular weights of 47, 51 and 52 K possibly representing synaptic proteins increased with time in culture. The appearance of a prominent band (60 K) in brain cultures and in other cells of divergent origin was demonstrated. This protein may be related to the process of cell adaptation to culture conditions. The developmental changes in the protein profile are discussed in the context of an in vitro myelinogenesis and synaptogenesis and compared with whole brain particulate and subcellular fractions.     

DEMONSTRATION OF ACID PHOSPHATASE-CONTAINING GRANULES AND CYTOPLASMIC BODIES IN THE EPITHELIUM OF FOETAL RAT DUODENUM DURING CERTAIN STAGES OF DIFFERENTIATION

Dense cytoplasmic bodies surrounded by one or two unit membranes and containing mitochondria, vesicles, ribosomes, rough and smooth surfaced endoplasmic reticulum, and lamellated membranes (myelin figures) have been observed in the differentiating mucosa of the duodenum of rat foetuses by electron microscopy. Generally, the cytoplasmic components in the bodies seem to be in varying stages of disintegration. The bodies are found in greatest number on the 17th and 18th day of gestation, i.e. at the onset of differentiation. At this period of development the epithelium is stratified, and the villus formation is initiated by invagination of the epithelium by buds of mesenchyme followed by a splitting of the epithelium along the sides of the invaginations. When the villi have formed, the stratified epithelium has changed to the simple columnar type and the dense bodies have largely disappeared. Simultaneously, the lumen has widened considerably. In a parallel study with the light microscope, frozen sections incubated for the demonstration of acid phosphatase activity revealed the reaction product to be localized in bodies of the same size and distribution as the dense bodies found by electron microscopy. Hence, it seems that the bodies are altered and enlarged lysosomes (cytolysomes) active during the intensive differentiative events in the small intestine during the last part of intra-uterine life.     

小鼠B淋巴细胞活化过程中Ly—5（B220）的表达

本文通过ＦＡＣＳ技术,利用单克隆抗体ＲＡ３－６Ｂ２抗Ｌｙ－５（Ｂ２２０）研究了Ｌｙ－５（Ｂ２２０）在新制备的小鼠脾脏Ｂ细胞上的表达,特别是用不同的丝裂原刺激而激活Ｂ细胞后Ｌｙ－５（Ｌｙ－５ｈｉ）,浮力密度较低的大Ｂ细胞则为Ｌｙ－５＾ｌｏｗ。用多允隆刺激因子ＬＰＳ（细菌脂多糖）刺激脾脏高浮力密度小Ｂ细胞,可诱导Ｌｙ－５的表达仍保持较高状态,但当用抗－ＩｇＭ与白细胞介素－６一起刺激时,则诱导Ｌｙ－５的