Retinal photoreceptor fine structure in the velvet cichlid (Astronotus ocellatus).

Summary The structure and arrangement of the retinal photoreceptors of the velvet cichlid fish (Astronotus ocellatus) have been studied by light and electron microscopy. Rods, single cones and double (twin) cones are present. In the light-adapted state, rods are very tall cells that reach deep into the retinal epithelial (RPE) layer. The long outer segment is composed of discs of uniform diameter displaying one or two incisures. The rod inner segment shows a distal ellipsoid of mitochondria, and then narrows dramatically in the myoid region. Rod nuclei are electron dense and located deep in the outer nuclear layer. Rod synaptic spherules are small and show two to three invaginated synaptic sites as well as superficial synapses. Single cones are similar to the individual members of a double cone and all display a short tapering outer segment, a large ellipsoid of mitochondria and a myoid rich in rough endoplasmic reticulum, polysomes, Golgi zones and autophagic vacuoles. Double cones have extensive subsurface cisternae along their entire contiguous surfaces. Cone nuclei are large and vesicular and located close to or through the external limiting membrane. The synaptic pedicles of cones are larger, more electron lucent, and display more invaginated (ribbon) synapses as well as conventional (superficial) synaptic sites than do the rod spherules. Rod photoreceptors certainly undergo retinomotor movements and it is probable that cones do as well. In the light-adapted state the cone photoreceptors are arranged in a repeating square mosaic pattern with one single cone surrounded by four double (twin) cones.     

Adenosine protects ultrastrueture of isolated rat lungs against fat emulsion injury

In isolated rat lungs subjected to fat emulsion damage, a model simulating adult respiratory distress syndrome, we have previously reported that adenosine (ADO) reduces pulmonary vascular resistance (PVR) and the fluid filtration rate (FFR). In the present study the aim was to examine morphologically this effect of ADO. Two groups of isolated rat lungs were subjected to the injury. Marked and significant differences were found between the groups; in lungs not given ADO, FFR and airway pressure were higher and, as evaluated by electron microscopy, the endothelial lining was thin and partly disrupted. The epithelial cells of the alveolar walls were also partly disrupted and the alveolar septa were split enclosing interstitial edema. In lungs receiving ADO from the onset of exposure to fat emulsion, FFR was lower and ultrastructure did not differ from non–injured non–treated controls perfused for the same length of time.     

三硝基甲苯急性中毒对小鼠睾丸超微结构的影响

三硝基甲苯急性中毒后,小鼠睾丸的各级生精细胞,支持细胞及睾丸间质细胞的超微结构均有不同程度的改变,精子细胞的损伤较重,精原细胞的损伤较轻.生精细胞的损伤较支持细胞及睾丸间质细胞为重.     

Eosinophil cationic protein is stored in, but not produced by, peripheral blood neutrophils

BACKGROUND: Eosinophil cationic protein (ECP) is an eosinophil-derived protein, which has been shown to be present in circulating neutrophils. OBJECTIVE: To establish whether ECP is produced or internalized by peripheral blood neutrophils. METHODS: This was done using microscopy, flow cytometry, fractionation of cells and RT-PCR techniques. RESULTS: No ECP mRNA was detected after extensive cell purification to eliminate all traces of contaminating eosinophils. Examination of immunostained neutrophils by light, confocal, electron microscopy together with cell fraction experiments, established that ECP is present intracellularly and is mostly associated to cell granules. Uptake studies by flow cytometry and by using both cold and radiolabelled ECP showed that it is internalized by neutrophils and stored in some proportion in their primary granules. Upon stimulation with serum-treated Sephadex particles, the internalized ECP was partially released from cells. CONCLUSION: ECP is not produced but can be internalized by circulating neutrophils, which take it from the environment and partially store it in their primary granules.     

脑外科手术后发生正常灌注压突破的发病机制及超微病理基础

目的:探讨脑外科手术后部分患者病变邻近脑组织发生正常灌注压突破并发症的发病机制及其超微病理基础.材料和方法:对68例脑内血管畸形病变邻近的脑组织进行电子显微镜观察.结果:病灶邻近脑组织内部分毛细血管外周的星形细胞足突缺失或出现血管基膜疏松、分层等发育不良的情况,甚至有些血管壁组织结构破损.结论:电子显微镜检查证实,在血管畸形病灶周围的脑组织内可见病理性血管.该血管的基膜发生病变,血管周围的星形细胞足突明显减少或破坏.当血液灌注压力突然变化时,这种病变的血管就可能发生液体外渗及破裂.这就是在神经外科手术中或手术后发生正常灌注压突破并发症的超微病理基础.     

Selective localisation of neuro-specific T lymphocytes in the central nervous system

Using experimental autoimmune encephalomyelitis (EAE) in the rat as a model of central nervous system (CNS) inflammation, activated and quiescent T lymphocytes with different antigen specificities were labelled with the fluorescent dye Hoechst 33342 and tested by fluorescence microscopy for their ability to accumulate in different regions of the spinal cord and in other organs at varying times post inoculation. With this highly sensitive assay it was found that activated myelin basic protein (MBP)-specific T cell lines accumulated in the spinal cord (a 1000-fold increase in the lumbar/sacral region by day 4) and caused clinical signs of EAE. In contrast, interleukin-2 (IL-2)-maintained (quiescent) MBP-specific T cell lines failed to accumulate in the CNS and cause disease. Activated ovalbumin (OA)-specific and purified protein derivative of tuberculin (PPD)-specific T cell lines were also found at significantly higher levels in the spinal cord than non-activated cells although they failed to accumulate to a substantial degree when injected alone. When injected with activated MBP-specific T cells the activated OA- and PPD-specific cell lines accumulated in the spinal cord following initial accumulation of the MBP-specific cells, demonstrating that during the inflammatory process there is considerable non-specific recruitment of cells into the inflammatory site. CNS accumulation of activated MBP-specific T cell lines occurred 1-2 days later in irradiated animals than in non-irradiated recipients. This was consistent with irradiated animals also exhibiting a later onset of disease and suggests that irradiation may directly affect the endothelium in a way that makes it less adhesive. In conclusion, this study demonstrates that activated lymphocytes of any specificity enter the spinal cord, and that the neuro-antigen specific cells accumulate there and lead to the recruitment of other cells. Non-activated cells, even those with neural antigen specificity fail to enter the cord. Understanding the nature of what an 'activated' lymphocyte is may allow us to design strategies to inhibit such immune-mediated inflammation.     

Neuronal vacuole formation in the rat posterior cingulate/retrosplenial cortex after treatment with the N-methyl-d-aspartate (NMDA) antagonist MK-801 (dizocilpine maleate)

Cytoplasmic vacuoles appear in neurons of the posterior cingulate/retrosplenial cortex (PC/RS) of rats after treatment with N-methyl-d-aspartate (NMDA) receptor antagonists. Prominent dilatation of mitochondria and endoplasmic reticulum has been described within 2 h; however, the ultrastructural features of vacuole formation are unknown. To investigate this, the present study examined the PC/RS cortex of male rats (age 60–70 days) at 15, 30, 45, 60, 90, and 120 min after subcutaneous treatment with 1 mg/kg of the noncompetitive NMDA antagonist MK-801 (dizocilpine maleate, 5-methyl-10, 11-dihydro-5H-dibenzo [a,d] cyclohepten-5,10-imine). Subtle mitochondrial dilatation was identified in a few neurons as early as 15 min postdose (MPD). By 30 MPD, dilatation was more pronounced in mitochondria and also involved the endoplasmic reticulum and perinuclear space. Ribosomal disaggregation and degranulation were also evident by 30 MPD. At all subsequent time points, dilatation of mitochondria and endoplasmic reticulum progressed in severity. Although the relative involvement of mitochondria and endoplasmic reticulum varied, glia were not involved. These ultrastructural data suggest that after treatment with MK-801, mitochondrial dilatation precedes involvement of endoplasmic reticulum in vacuolization of susceptible PC/RS cortical neurons. The early mitochondrial effects identified in this study suggest an initial metabolic insult that rapidly progresses to affect endoplasmic reticulum and ribosomes. This strengthens the relationship between the ability of certain NMDA antagonists to induce energy perturbations and neuronal vacuoles in the same region of the rat cerebral cortex.     

Immunohistochemical, ultrastructural and immunoelectron microscopic studies of spinal cord neurofibrillary tangles in progressive supranuclear palsy

Immunohistochemical, ultrastructural and immunoelectron microscopic studies of spinal cord neurofibrillary tangles (NFTs) in progressive supranuclear palsy (PSP) were performed. The spinal cord NFTs reacted with antibodies to tau protein (tau-2), ubiquitin and Alzheimer neurofibrillary tangles (ANTs, Ab 39). Ultrastructurally, the NFTs consisted of bundles of straight fibrils. In longitudinal sections, the individual NFT fibrils appeared as straight fibrils with a diameter of approximately 15 nm. In cross sections, circular structures approximately 15 nm in diameter were seen, and some had a central density. Electron microscopic examination of specimens stained with the antibodies and by the modified Bielschowsky method revealed the products of the tau, ubiquitin and ANTs immunoreactions and silver deposits on the NFT fibrils. This is the first demonstration of the ultrastructure of spinal cord NFTs in PSP.     

1000例正常人发电子自旋共振（ESR）波谱的饱和特性研究

本文报道1000例正常人发自由基的电子自旋共振波谱饱和功率(ESR-SP)的检测结果。所得正常值的全组中位数为2.496mw;95％上下限分别为2.989及1.720mw。如按性别统计,则女性下限(1.617mw)较男性(1.983mw)为低,(P<0.05)。按年龄分别统计,则40岁以上的中位数(2.376mw)及其下限(2.009mw)高于40岁以下的中位数(2.548mw)及其下限(1.597mw),两者差异有显著性(P<0.05)及极显著性(P<0.01)。因此在使用此正常值指标时,必须注意性别与年龄因素。     

Alpha and gamma motoneurons in the peroneal nuclei of the cat spinal cord: an ultrastructural study.

The aim of the present study was to investigate whether ultrastructural features can be used as a guide to identify alpha- and gamma-motoneurons among the intermediate-size neurons of the peroneal motor nuclei. The peroneus brevis and peroneus tertius muscles of adult cats were injected with horseradish peroxidase, and motoneurons labeled by retrograde axonal transport were examined by electron microscopy. In both nuclei, the distributions of cell-body diameters, measured in the light microscope, were bimodal covering the range of 28-84 microns, with a trough around 50 microns. The sample of 25 motoneurons selected for the ultrastructural study included not only large (presumed alpha) and small (presumed gamma) neurons but also intermediate-size cell bodies with diameters in the 40-60 microns range. For each motoneuron, 2-5 profiles were reconstructed from ultrathin sections taken at 6-8 microns intervals. Synaptic boutons were counted and their lengths of apposition were measured. On the basis of three criteria, namely: (1) bouton types present on the membrane, (2) percentage of membrane length covered by synapses, and (3) the aspect of the nucleolus, all the examined motoneurons, including those with intermediate sizes, fell into one of two categories. Fourteen motoneurons, with cell-body diameters in a range of 55-84 microns, were contacted by all types of boutons (mainly S-type with spherical vesicles, F-type with flattened vesicles, and C-type with subsynaptic cistern); the synaptic covering of the somatic membrane was over 40% and the nucleus contained a vacuolated nucleolus. These were considered alpha-motoneurons. Eleven motoneurons, with only S and F boutons, a synaptic covering under 30%, a compact nucleolus and a cell-body diameter ranging between 28 and 50 microns, were considered gamma-motoneurons. No other combination of the three criteria was observed. These results show that unequivocal distinction of alpha- and gamma-motoneurons is possible in the peroneal nuclei, on the basis of morphological differences independent of cell-body size.