小白鼠腹膜间皮的扫描电镜观察及机能探讨

我们用扫描电镜观察了5只小白鼠的脏、壁层腹膜间皮及肠系膜腹膜间皮,发现腹膜间皮细胞表面有排列形式不一,形态各异的微绒毛、火山口样凹陷、细胞表面的圆形缺损区及颗粒等。在肠系膜腹膜间皮还发现了细胞间孔。我们还观察到间皮细胞具有六种不同的形态。     

猫、兔、鼠侧脑室脉络丛的扫描电镜观察

本文报道用扫描电镜观察猫、兔和大白鼠侧脑室脉络丛的微细结构。3种动物侧脑室脉络丛表面均可见密集的微绒毛、散在的纤毛簇、单个的纤毛、球样突起和花样结构。在高倍镜下,微绒毛又可分为两型,即尖细的指样绒毛和末端膨大成泡样的微绒毛。并发现有呈花样密集排列的微绒毛簇。同时在3种动物的侧脑室脉络丛表面均可见kolmer细胞,根据突起的多少可将此类细胞分成为单极、双极,多极、无伪足样突起四型。猫的侧脑室脉络丛的球样突起和大白鼠的纤毛簇较多。     

人体腹膜壁层间皮细胞微绒毛的超微结构

本文应用扫描电镜、透射电镜和冷冻复型技术对16例人体腹膜壁层间皮进行了观察。结果表明腹膜间皮细胞表面均有微绒毛,但不同部位微绒毛的长短、疏密和排列的方式不同。有的绒毛具有一些特殊形态:(1) 鼓槌状微绒毛;(2) 分叉状微绒毛;(3) 一根微绒毛主干上有多根次级微绒毛;(4) 微绒毛内含有吞饮小泡;(5) 微绒毛根部或其边缘有吞饮小泡开口。     

人蛛网膜绒毛的扫描电镜观察

用扫描电镜研究了正常人的蛛网膜绒毛的三维结构。观察到人的蛛网膜绒毛的上皮间存在着较宽的裂隙较小的孔洞。在上皮的表面可见微绒毛和球样突起。根据形态可把微绒毛分为两类：棒样微绒毛和末端有泡的微绒毛，策绒毛的分布不是均匀一致的，偶尔可见微绒毛聚信成花样结构。     

dbcAMP对小鼠U_(14)腹水型瘤细胞的影响——扫描电镜观察和流式细胞光度计分析

本文根据扫描电镜观察,报告了dbcAMP引起小鼠U_(14)腹水瘤细胞微绒毛和质膜表面的细微形态变化。U_(14)腹水瘤的多数细胞体积大,大小相近,表面有许多细长微绒毛;微绒毛表面和微绒毛间细胞质膜表面,仅见很细微的点状微突。腹腔内注射dbcAMP的U_(14)腹水瘤,85％以上的细胞体积缩小,大小不等,表面微绒毛缩短且减少。在没有微绒毛的部位,细胞质膜表面有许多颗粒状微突起,较对照组明显易见。微绒毛表面也有与之大小类似的微突起,使微绒毛表面凹凸不平。流式细胞光度计分析结果表明,在本文实验条件下,dbcAMP未引起U_(14)腹水瘤细胞周期的变化,细胞膜表面和微绒毛的变化,也不单纯是细胞周期中微绒毛数量和分布的改变。因此作者认为,这些变化不是通过改变细胞周期引起的。 cAMP引起微绒毛退缩的机制不详。至于微绒毛间的颗粒状微突起是微绒毛退缩的遗迹,抑或是由cAMP引起,尚待研究。cAMP引起瘤细胞表面形态的变化,进一步证明了cAMP在小鼠体内诱导恶性细胞分化的作用。     

人胎儿胃肠道的扫描电镜观察

用扫描电镜技术对10周～足月胎儿胃肠道的表面形态进行了观察。结果表明:10周时胃表面凹凸不平,胃小凹原基形成,小肠及结肠均可见有呈指状的绒毛。13周后,胃表面呈脑回状,胃粘膜细胞表面有密集的微绒毛;空肠及回肠绒毛更为发达,结肠绒毛逐渐开始退化。20周以后,胎儿胃粘膜表面扫描图象与成人已基本相似,在小肠上瑞多数绒毛顶部可见有一直径为100～300微米的凹陷,此即:“濑木帽”。结肠绒毛在20周以后则消失。上述结果提示,在妊娠前20周是胎儿胃肠粘膜进行形态发生和细胞分化的时期,20周以后则是逐渐完善其结构功能的时期。     

大鼠侧脑室海马表面超微结构的扫描电镜观察

目的为进一步认识“脑一脑脊液神经体液回路”提供形态学资料。方法将9只大鼠灌注固定后,剥离海马并制成扫描电镜样品,在扫描电镜下观察。结果（1）大鼠海马伞的室管膜表面覆盖着大量的纤毛和微绒毛;而海马体的室管膜表面主要以微绒毛为主。（2）吞噬细胞多分布于海马伞;神经元样细胞多存在于海马体。室管膜上神经纤维可存在于海马伞的多纤毛区,也可存在于海马体的少纤毛区。结论大鼠海马表面分布有微绒毛、纤毛、室管膜上细胞和室管膜上神经纤维等结构,这些结构与室管膜细胞一起构成了“脑一脑脊液神经体液回路”的结构基础。     

大鼠大网膜表面的扫描电镜观察

大白鼠大网膜不同结构区——薄膜区、脂肪和血管区的表面均有一层间皮和散在的乳斑。同皮细胞间借突起相接。突起之间可见宽窄不一的间隙。薄膜区间隙较大,呈网络状。间皮细胞表面有疏密不均的微绒毛。微绒毛或离散分布,或连接成网。在微绒毛稀少区的细胞表面可见散在的小孔。在脂肪和血管区有丰富的乳斑,薄膜区乳斑少见且较少。乳斑的细胞多数位于间皮细胞间的间隙内或其表面。乳斑细胞的绝大部分裸露于腹膜腔。乳斑的细胞成分主要为巨噬细胞和淋巴细胞,有少数颗粒白细胞和红细胞,偶见肥大细胞。     

改良法体外培养大鼠脑膜间皮细胞

建立大鼠脑膜间皮细胞(rat meningeal mesothelial cells,RMMC)的体外原代培养模型。用机械吹打法和0.25%胰酶-0.01%EDTA轻消化法收集原代细胞,多次差速黏附处理及传代。传三代,分别进行倒置相差显微镜观察细胞大体结构、扫描电镜(SEM)观察细胞超微结构、苏木素伊红(HE)染色法观察细胞形态、细胞免疫荧光法及免疫细胞化学法鉴定细胞。结果显示:分离培养的原代细胞在倒置显微镜下为多边形,汇合时呈铺路石样排列;SEM下细胞表面可见大量密集的微绒毛;免疫荧光染色结果显示培养细胞呈细胞角蛋白抗原阳性;免疫细胞化学结果显示培养细胞呈细胞角蛋白和波形蛋白抗原阳性,第Ⅷ因子相关抗原阴性,培养细胞的纯度达96%以上。结论:本实验成功建立了RMMC培养模型,可为脑膜纤维化的形成机制研究提供理想的细胞模型。     

胸膜间皮瘤病理学诊断研究进展

胸膜间皮瘤是一种少见肿瘤，但近年其发病率有逐年增加趋势。由于间皮的多潜能分化功能致使恶性间皮瘤细胞形态多种多样，在光镜下与胸膜转移性腺癌、反应性间皮细胞及其它梭形细胞肿瘤不易鉴别，给临床和病理诊断工作带来困难。近年由于对胸膜间皮瘤认识水平的提高和电镜...     

Response of air sac mesothelium to expansion of extracellular fluid volume in Gallus domesticus

In this study, scanning electron microscopy was used to examine the effects of hydrothorax on the morphology of the air sac visceral mesothelium of Gallus domesticus. Anaesthetized chickens were subjected to acute hydrodynamic pulmonary oedema induced by expansion of the extracellular fluid volume with an infusion of Ringer's solution equal to 6.5% of body weight. Tissue samples from the visceral surface of the abdominal air sacs near their ostia were obtained and fixed after death induced by anaesthetic overdose. These were compared with similar samples from control "non-volume-loaded" birds. The air sac visceral mesothelium of the volume-loaded animals presented an increased density of bulbous or swollen microvilli. These deformations were similar to changes reported in the visceral pleura of mammals subjected to hydrothorax, suggesting a commonality with regard to the role of these mesothelia in liquid clearance during pulmonary oedema.     

Malignant pleural mesothelioma: Clinicopathology of 16 extrapleural pneumonectomy patients with special reference to early stage features

The earliest pathological events in the development of malignant pleural mesothelioma (MPM) are not understood. The aim of the present study was to elucidate the early histopathological features of MPM. A total of 16 extrapleural MPM pneumonectomy patients were investigated. Early stage mesothelioma was arbitrarily defined as a tumor ≤5 mm in thickness regardless of the nodal status or other organ involvement. Eight of these patients (six with epithelioid, two with biphasic) had early stage mesothelioma by this definition. Macroscopically there was no visible tumor, but the parietal and visceral pleura were thickened and there was focal adhesion between them. Microscopically, the mesothelioma lesions were multifocal and discontinuous on the pleura. In extremely early cases of epithelioid mesothelioma, tumor cells were generally arrayed in a single layer, but papillary proliferation was observed elsewhere. In sarcomatoid mesothelioma, mesothelioma cells proliferated, forming multiple small polypoid nodules on the pleura. Epithelial membrane antigen was helpful to distinguish reactive from neoplastic mesothelium, but glucose transporter-1 was not. Mesothelioma cells disseminate diffusely throughout the parietal and visceral pleura and mediastinal fat tissue before becoming visible. Stage Ia mesothelioma (neoplasm limited to the parietal pleura) would not be observed in daily practice.     

Scanning and transmission electron microscopic study of visceral and parietal peritoneal regions in the rat

The visceral peritoneum of intraabdominal organs (spleen, stomach, liver, small intestine), omentum majus and the parietal peritoneum of the anterior abdominal wall and the diaphragm were studied in adult Wistar rats by combined scanning and transmission electron microscopy (SEM, TEM). In general, the peritoneal surface consisted of a mesothelium composed of cubic, flat or intermediate cell types delimited by a basal lamina. Cubic mesothelial cells predominated in parenchymal organs (spleen, liver) and were characterized by prominent and indentated nuclei, a cytoplasm richly supplied with organelles, a dense microvillous coat, basal invaginations and elaborate intercellular contacts. Flat mesothelial cells were observed in the intestinal, omental and parietal peritoneum (tendinous diaphragm, abdominal wall) and showed elongated nuclei, scant cytoplasm, a poorly developed organelle apparatus and sparsely distributed microvilli. An intermediate mesothelial cell type was described within the gastric peritoneum characterized by a central cytoplasmic protrusion at the nuclear region containing most of the cytoplasmic organelles and by thin finger-like cytoplasmic processes. The submesothelial connective tissue layer was composed of collagen fiber bundles, fibroblasts and free cells (macrophages, granulocytes, mast cells) and contained blood and lymphatic vessels. In the spleen, elastic fibers formed a membranous structure with intercalated smooth muscle cells. Mesothelial openings were observed as tunnel-like invaginations within the hepatic peritoneum and as clusters of peritoneal stomata within the parietal peritoneum of the anterior abdominal wall and the muscular diaphragm. The round or oval openings of the peritoneal stomata were frequently occluded by overlapping adjacent mesothelial cells and their microvillous coat or obstructed by cellular material. At the side of the peritoneal stomata the mesothelial cell layer was interrupted to allow a direct access to the underlying submesothelial lymphatic system. The mesothelium and lymphatic endothelium shared a common basal lamina. The endothelial cells were discontinuous and displayed valve-like plasmalemmatic interdigitations facilitating an intercellular transport of fluids and corpuscular elements from the peritoneal cavity to the submesothelial lymphatic lacunae. The findings underline the morphological heterogeneity of the peritoneum in visceral and parietal regions, suggesting different functional implications, and further support the presence of extra-diaphragmatic peritoneal stomata.     

Friction and lubrication of pleural tissues

The frictional behaviour of rabbit's visceral pleura sliding against parietal pleura was assessed in vitro while oscillating at physiological velocities and amplitudes under physiological normal forces. For sliding velocities up to 3 cm s(-1) and normal compressive loads up to 12 cm H2O, the average value of the coefficient of kinetic friction (mu) was constant at 0.019 +/- 0.002 (S.E.) with pleural liquid as lubricant. With Ringer-bicarbonate solution, mu was still constant, but significantly increased (Deltamu = 0.008 +/- 0.001; P < 0.001). Under these conditions, no damage of the sliding pleural surfaces was found on light and electron microscopy. Additional measurements, performed also on peritoneum, showed that changes in nominal contact area or strain of the mesothelia, temperature in the range 19-39 degrees C, and prolonged sliding did not affect mu. Gentle application of filter paper increased mu approximately 10-fold and irreversibly, suggesting alteration of the mesothelia. With packed the red blood cells (RBC) between the sliding mesothelia, mu increased appreciably but reversibly on removal of RBC suspension, whilst no ruptures of RBC occurred. In conclusion, the results indicate a low value of sliding friction in pleural tissues, partly related to the characteristics of the pleural liquid, and show that friction is independent of velocity, normal load, and nominal contact area, consistent with boundary lubrication.     

Tight junction proteins contribute to barrier properties in human pleura

The permeability of pleural mesothelium helps to control the volume and composition of the liquid lubricating pleural surfaces. Information on pleural barrier function in health and disease, however, is scarce. Tissue specimens of human pleura were mounted in Ussing chambers for measurement of transmesothelial resistance. Expression of tight junction (TJ) proteins was studied by Western blots and immune fluorescence confocal microscopy. Both visceral and parietal pleura showed barrier properties represented by transmesothelial resistance. Occludin, claudin-1, -3, -5, and -7, were detected in visceral pleura. In parietal pleura, the same TJ proteins were detected, except claudin-7. In tissues from patients with pleural inflammation these tightening claudins were decreased and in visceral pleura claudin-2, a paracellular channel former, became apparent. We report that barrier function in human pleura coincides with expression of claudins known to be key determinants of epithelial barrier properties. In inflamed tissue, claudin expression indicates a reduced barrier function.     

Na+-glucose cotransporter is also expressed in mesothelium of species with thick visceral pleura

Molecular evidence for Na+-glucose cotransporter (SGLT1) in rabbit pleural mesothelium has been recently provided, confirming earlier functional findings on solute-coupled liquid absorption from rabbit pleural space. In this research we checked whether SGLT1 is also expressed in pleural mesothelium of species with thick visceral pleura, which receives blood from systemic circulation, but drains it into pulmonary veins. To this end immunoblot assays were performed on total protein extract of scraped visceral and parietal mesothelium of lambs and adult sheep, and of a human mesothelial cell line. All of them showed SGLT1 specific bands. Moreover, confocal immunofluorescence images of lamb pleural mesothelium showed that SGLT1 is located in apical membrane. Therefore, a solute-coupled liquid absorption should also occur from pleural space of species with thick visceral pleura. Because of this protein-free liquid entering interstitium between visceral mesothelium and capillaries, inherent Starling forces should be different than hitherto considered, and visceral pleura capillaries could absorb liquid even in these species.     

The structure of the parietal pleura and its relationship to pleural liquid dynamics in sheep

We studied the parietal pleura of six sheep to obtain information on pleura structure, blood supply, and lymphatic drainage. In the strict sense, the parietal pleura is composed of a single layer of mesothelial cells and a uniform layer of loose, irregular connective tissue (about 23 μm in width) subjacent to the mesothelial cells. The parietal pleural blood vessels are 10–15 μm from the pleural space. Tracer substances put in the pleural space are removed at specific locations. Colloidal carbon and chick red blood cells are cleared by teh parietal pleural lymphatics located over the intercostal spaces at the caudal end of the thoracic wall and over the lateral sides of the pericardial sac. In these areas the mesothelial cells have specialized openings, the stomata, that directly communicate with the underlying lymphatic lacunae. Cells and particulate matter in the pleural space are cleared only by the parietal pleural lymphatics. Compared to the visceral pleura, we believe the thinness of the parietal pleura, the closeness of its blood vessels to the pleural space, and its specialized lymphatic clearance pathways, together indicate that the parietal pleura plays a major role in pleural liquid and protein dynamics in sheep.     

Effect of adrenaline on transmesothelial resistance of isolated sheep pleura

The effect of adrenaline on the transmesothelial resistance (RTM) of sheep's visceral and parietal pleura was studied using the Ussing chamber technique. Basal transmesothelial resistance of visceral pleura was found to be 20.71 +/- 0.31 Omega cm2, whereas that of parietal pleura was found to be 19.53 +/- 0.34 Omega cm2. Immediately after the addition of adrenaline (10(-7) M) both apically and basolaterally on the visceral and parietal pleura, these values were significantly increased (P < 0.05). Addition of the nonselective beta-receptor blocker, propranolol (10(-5) M), suppressed this effect in both visceral and parietal pleura, while addition of the nonselective alpha-receptor blocker, phentolamine (10(-5) M), partly suppressed the above-mentioned increase in the parietal pleura. In conclusion, our results show that adrenaline has a rapid effect on both pleurae. This rapid effect is mediated by the stimulation of beta-adrenergic receptors in the case of visceral pleura, while in the case of parietal pleura this effect seems to be due to a stimulation of alpha- and beta-adrenergic receptors. On the visceral pleura the effect of adrenaline vanishes after some minutes and on the parietal this effect is more permanent than the visceral's one, suggesting differences in the distribution of the adrenergic receptors between the visceral and parietal pleura.     

Spontaneous mesotheliomas in Fischer rats--a histological and electron microscopic study

Seventeen mesotheliomas from 395 untreated male Fischer 344/DuCrj rats were studied by light and electron microscopy to define the morphological characteristics of the tumors. In 16 out of 17 rats, mesotheliomas were observed in the abdominal and/or scrotal sac, and the other one was localized on the pleura. Grossly, tumors were yellow-brown with various-sized multiple modules growing irregularly over the surface of the serosa. Microscopically, they varied from complex papillary to sessile nodular growths. Tumor cells were cuboidal to polygonal with round to oval nuclei, and were sometimes arranged in tubule-like structures. Occasionally, the cells contained Mowry's colloidal iron positive materials, which were negative following prior incubation with hyaluronidase. Furthermore, intracellular keratins were detected using the peroxidase-antiperoxidase method. Ultrastructural features of tumor cells included numerous microvilli, a basement membrane, junctional complexes, abundant cytofilaments, dilated rough surfaced endoplasmic reticulum cisternae, and a well-developed Golgi apparatus. The morphological characteristics of these tumors in Fischer 344 rats were consistent with those in humans and with experimentally induced counterparts in rats. The histogenesis of these tumors and the variability in their incidence following oral administration of chemical carcinogens is discussed.