Clefts in Intradermal Nevi: An Ultrastructural Study

Six intradermal melanocytic nevi, two with and four without intercellular slitlike spaces, were examined by light microscopy and electron microscopy of deparaf-finized tissue. The spaces were partially lined by elongated nevus cells and contained a few collagen fibrils. Other features in both groups included an abundance of (1) immature elastic tissue comprised of aggregates of microfibrils lacking an amorphous component and (2) collagen fibrils that were finer than in normal dermis and did not form compact bundles. We propose that these elastic tissue and collagen fiber changes diminish the resistance of the dermis to the mechanical stress of the biopsy procedure and histologic processing, resulting in the formation of artifactual clefts.     

家兔实验性动脉粥样硬化中内皮细胞的超微结构改变

通过电镜检查证明,喂了胆固醇的家兔主动脉及冠状动脉的内皮细胞胞质内出现吞饮小泡增多、质膜内陷及深度不同的管道样结构形成、内皮细胞间间隙扩张、胞质表面形成绒毛状突起及边缘皱襞的延长等,作者对这些变化的意义进行了分析讨论。     

Ultrastructural Changes of Caudate Nucleus in Mice Chronically Treated with Manganese

Manganese (Mn) is able to cross the blood–brain barrier and induces functional and structural alterations during the intoxication by this metal. Therefore, the effects of chronic administration of Mn in the caudate nucleus of mice were evaluated by electron microscopy. Male albino mice were injected intraperitoneally with MnCl₂ (5?mg/kg/d) 5?d per week during 9 weeks. The control group received only 0.9% of NaCl solution. The caudate nuclei were extracted and subsequently processed to be observed on a conventional transmission electron microscope at 2, 4, 6, and 9 weeks after treatment. A high percentage of vacuolated and swollen mitochondria were found throughout all the analyzed periods. Myelin disarrangement and ultrastructural alterations related to edema were observed increased in Mn-treated mice at week 9. Granular degeneration of myelin at week 9 accompanied with deposition of electron dense granules in the neuropil was also observed. Edema in neuropil and glial cells was detected from week 2 to week 9 accompanied by swollen mitochondria. Neuronal bodies, synaptic terminals, and perivascular cells were found swollen. Decreased electron density in postsynaptic areas and decreased and dispersed synaptic vesicles in presynaptic areas were noted in Mn-treated animals. Some neurons from Mn-treated mice showed cisternae dilation of the Golgi apparatus. These results suggest that Mn-treatment produces structural alterations in the caudate nucleus that could be responsible for some of the neurotoxic effects of this metal.     

Hepatic stellate cells express Ca2+ pump-ATPase and Ca2+-Mg2+-ATPase in plasma membrane of caveolae

Intracytoplasmic free calcium ions (Ca²⁺) are maintained at a very low concentration in mammalian tissue by the extrusion of Ca²⁺ across a steep extracellular Ca²⁺ gradient, mainly through the activity of plasma membrane Ca²⁺ pump-ATPase. The present study aimed to identify, by electron cytochemical and electron immunogold methods, the ultrastructural localizations of two types of plasma membrane Ca²⁺-ATPase; Ca²⁺-Mg²⁺-ATPase and Ca²⁺ pump-ATPase, in hepatic stellate cells. Liver tissues and isolated hepatic stellate cells (HSCs) were studied. The ultrastructural localization of Ca²⁺-Mg²⁺-ATPase activity was examined by the electron cytochemical method of Ando. The localization of Ca²⁺ pump-ATPase was identified by immunofluorescence. The ultrastructural localization of Ca²⁺ pump-ATPase was identified by the electron immunogold method. The cytochemical reaction products of Ca²⁺-Mg²⁺-ATPase activity were localized on the outer (cavity) side of the plasma membrane of caveolae. Immunofluorescence of Ca²⁺ pump-ATPase was seen as small dots along the cell edge in HSCs. Immunogold particles indicating the presence of Ca²⁺ pump-ATPase were identified on the inner (cytoplasmic) side of the plasma membrane of caveolae. We localized Ca²⁺ pump-ATPase on the inner side of the plasma membrane caveolae and Ca²⁺-Mg²⁺-ATPase on the outer leaflet of the caveolar plasma membrane in stellate cells, suggesting that Ca²⁺ pump-ATPase may play a key role in the Ca²⁺ reflux. Received: March 7, 2000 / Accepted: July 7, 2000     

免疫脾细胞及柯萨奇B-2病毒对小鼠心肌细胞超微结构的影响

培养的新生BALB/c小鼠搏动心肌细胞感染柯萨奇B-2病毒4h加同种小鼠腹腔接种该病毒7d后的脾细胞共同孵育1d,后者能轻度加重被感染心肌细胞的超微结构改变,包括局部细胞膜边界模糊;细胞质内呈较为严重的胞浆浓缩、不均一和空隙形成及闰盘解离等。小鼠心肌细胞感染柯萨奇B-2病毒3d,其超微结构改变较感染4h者严重。实验结果提示T细胞介导免疫及病毒本身在急性病毒性心肌炎的发病中都起重要作用。     

“All-or-none” cytochrome C oxidase positivity in mitochondria in chronic progressive external ophthalmoplegia: An ultrastructural—cytochemical study

Teased single muscle fibers from 6 patients with chronic progressive external ophthalmoplegia (CPEO) showed a segmental defect in cytochrome c oxidase (COX) activity. On ultrastructural–cytochemical examination, the majority of mitochondria in COX-positive segments were COX-positive, whereas all mitochondria in COX-negative segments were COX-negative. This “all-or-none” COX positivity in mitochondria in CPEO with deleted mitochondrial DNA can be explained by the “threshold effect,” which induces the tissue-specific involvement and clinical heterogeneity. © 1993 John Wiley & Sons, Inc.     

Cutaneous Malignant Hemangioendothelioma: Clinical and Histopathological Observations of Nine Patients and a Review of the Literature

Nine patients with cutaneous malignant hemangioendothelioma (CMHE) were reported in Okinawa. All the patients were elderly, between 75 and 93 years of age. Four patients were males and five were female. The onset of the disease ranged from 1 to 9 months before the first visit. Eight patients had lesions on the scalp, and one, on the face and cheek. The lesions were in the form of exudative erythematous purpura, erythematous purpuric ulcers, and tumors. One patient developed a systematic metastasis involving the lungs, heart and intestine, and two patients had local metastasis to the cervical lymph nodes. Histopathologically, the tumor vessels were proliferated irregularly and showed anastomosis. The lumens were lined by large and atypical endothelial cells. Most of the specimens were infiltrated with large numbers of red blood cells. By electron microscope, Weibel-palade bodies were found inside the tumor cells located at the peripheral part of the lesion. The patients were treated by irradiation, IL-2 injection, and/or surgery. They were treated for 3 months to 2 years. Eight patients died between 4 to 24 months after the onset of disease and one has survived. The prognosis was poor.     

Coincidental finding of May-Hegglin anomaly in a patient with end-stage renal failure.

We present two cases of May-Hegglin anomaly incidentally discovered in a patient and his brother during investigation of the patient for end-stage renal failure and workup for renal transplantation. Routine laboratory tests were performed and included a basically normal clotting profile. Ultrastructural studies of the May-Hegglin inclusions proved diagnostic, findings were compared with those of two similar granulocyte inclusion bodies, and nomenclature discrepancies that still exist in most references are again emphasized. The finding of the May-Hegglin anomaly in our patient appears to be incidental to the underlying renal disease. A successful renal transplant has been carried out in this patient. We now report on a patient and his brother in which the MHA was discovered during workup of the patient for end-stage renal failure and renal transplantation. No association between the underlying renal disease and the MHA could be demonstrated.     

Surface Features of Leukaemic Megakaryocytic Precursors

Megakaryoblasts and maturing megakaryocytic precursor cells from 5 patients with megakaryoblastic leukaemia were studied by scanning electron microscopy (SEM). The diagnosis in all cases had been established by ultrastructural cytochemistry on the basis of a positive platelet peroxidase reaction with negative staining for myeloperoxidase. 1 case presented as acute myelofibrosis and 4 as acute megakaryoblastic transformation of chronic granulocytic leukaemia. Under the SEM, megakaryoblasts and maturing megakaryocytic precursors showed typical surface features including the presence of rounded and irregular blebs, broad folds and pseudopodia. The nature of these surface blebs is still unclear but they probably represent surface membrane alterations relating to imminent platelet shedding at least in the more mature precursors. These surface microprojections are distinctly different from those encountered on leukaemic lymphoblasts, myeloblasts and monoblasts. It is suggested that SEM may be used in conjunction with the PPO reaction as in aid in the diagnosis of megakaryocytic leukaemias.