Occlusion and subsequent re-canalization in early duodenal development of human embryos: integrated organogenesis and histogenesis through a possible epithelial-mesenchymal interaction

Histogenesis of the duodenum, especially changes in the epithelium in relation to temporal occlusion and re-canalization of the lumen, was investigated by light microscopy together with morphometric analysis, as well as by scanning and transmission electron microscopy of 133 externally normal human embryos ranging from Carnegie stage 12 to 23. A series of morphogenetic events passed the duodenum in a cranio-caudal (proximo-distal) wave like fashion during the period examined. They included: (1) a decrease in the caliber and area of the lumen, (2) ’occlusion’ of the lumen, (3) vacuole formation, (4) ’re-canalization’ and villi formation. The only exemption to this rule was that, in the upper part of the duodenum, the lumen was not obliterated in the embryos examined. Morphometric analyses revealed that both the area of the epithelium and the number of epithelial cells decreased during the ’occlusion’ phase. This result suggests that, unlike the classical view, epithelial cell proliferation does not play an important role in occluding the lumen, but the predominant morphogenetic event during this phase is convergence of the epithelial cells to elongate the duodenum. Apoptosis, contrary to some classical views, decreased during the ’re-canalization’ phase, and it appeared to be involved in the formation of the small lumens in the epithelial ’plug’ and in villi formation, but not in enlarging the secondary lumens. The secondary small lumens in the occluded lumen were frequently formed near the border between the central ’plug’ and peripheral basal cells on the basement membrane. This and other findings of concentric differentiation in both the epithelial and mesenchymal layers suggested a possible control mechanism by the epithelium-mesenchymal interaction on human duodenal morphogenesis and histogenesis. The present electron microscopic observations also provided details on the mechanisms involved in the enlargement of the secondary lumen and differentiation of villi. The implications of these findings to duodenal anomalies are also discussed. Accepted: 12 November 2001     

Ultrastructure and membrane permeability of cultured pancreaticβ-cells exposed to alloxan or 6-hydroxydopamine

Summary Stereological techniques on electron microscopy micrographs were used to evaluate the morphological changes of cultured islet cells that had been exposed to alloxan or 6-hydroxydopamine.Trypan Blue exclusion by cells cultured for 3 days indicated that the cells were 100% viable. Electron microscopy revealed that nearly all of the surviving cultured cells were cells.Exposure to 5 mmol/l alloxan or 1–5 mmol/l 6-hydroxydopamine for 10 or 30 min caused a general swelling of the cultured cells with a concomitant swelling of mitochondria and nuclei. The size of the secretory granules was not affected by the drugs. Only 3–10% of the cells excluded Trypan Blue after exposure to 5 mmol/l alloxan or 6-hydroxydopamine.The data conform with the hypothesis that a primary action of alloxan and 6-hydroxydopamine is at the plasma membrane level of cells.Abbreviations and definitions A _cell Cell profile area (µm²), surface area of one cell section surface - V _n Nuclear volume density (%), number of points over the nucleus divided by the number of points over the total cell area × 100 - V _m Mitochondrial volume density (%), number of points over mitochondria divided by hits over the cytoplasm (points over the cell minus points over the nucleus) × 100 - V _g Granular volume density (%), number of points over granules divided by hits over the cytoplasm × 100     

Elastofibroma dorsi has distinct cytomorphologic features, making diagnostic surgical biopsy unnecessary: cytomorphologic study with clinical, radiologic, and electron microscopic correlations

Elastofibroma dorsi (EFD) is a relatively rare soft tissue mass, probably of reactive nature. The lesion is typically located near the inferior margin of the scapula or between the inferior part of scapula and the chest wall in elderly women. Although location of the tumor together with the age/sex of the patients and radiologic findings is often suggestive of the diagnosis, tissue examination has been considered necessary to confirm the diagnosis. Although the histologic features of EFD are well known, there are only four single case reports of the cytologic findings in the English language literature. We describe the cytologic features of EFD in five patients with correlations to clinical, radiologic, histologic, and electron microscopic findings. The current study suggests that the fine-needle aspiration (FNA) features are highly diagnostic, permitting a firm diagnosis of EFD in a typical clinical setting and eliminating the need for preoperative histologic examination.     

Papovavirus detection by electron microscopy in the brain of an elderly patient without overt progressive multifocal leukoencephalopathy

Virions resembling papovavirus were demonstrated in glial cells in the brain of an aged patient without overt progressive multifocal leukoencephalopathy. The patient was not in a severely immunocompromised state. On histological examination, only a few tiny incomplete necrotic foci were found in the subcortical area. These foci were widely dispersed. Rare, swollen oligodendroglial cells and astrocytes in which papovavirus capsid protein (VP-1) was demonstrated immunohistochemically were present around the foci. The two typical types of virus particles i.e. 35 to 40 nm round particles and elongated particles, were observed in the nuclei of the swollen glial cells. The latter were in the minority. Distinct crystals were also found in the nuclei. The centre-to-centre distance of the particles in the crystals, about 40 nm, and the electron-opaque spots of the round-shaped virions and of the elongated particles, were indicative of structural subunits of papovavirus capsids. This case provides further evidence that papovavirus, possibly JC virus, may be reactivated in the brains of aged patients who are not in an immunocompromised state.     

Interferon Gamma Alters the Phenotype of Rat Thymic Epithelial Cells in Culture and Increases Interleukin-6 Production

Rat thymic epithelial cells (TEC) in long-term culture were characterized by anticytokeratin monoclonal antibodies (mAbs) and electron microscopy. Phenotypic analysis performed by a large panel of mAbs showed that the highest percentage of these cells was of the subcapsular/medullary type. Recombinant rat interferon (IFN)-gamma up-regulated class-I and class-II MHC expression by TEC in culture as confirmed by immunohistochemistry and flow cytometry, but did not significantly alter other cell markers. TEC supernatants of IFN-gamma- treated cultures showed higher interleukin-6 (IL-6) activity, compared to the control, as determined by proliferation of the IL-6-sensitive B9-cell line. Increased IL-6 activity was probably not a consequence of increased TEC number in IFN-gammatreated cultures because IFN did not significantly stimulate TEC proliferation in vitro. In contrast, IL-6 significantly stimulated TEC proliferation, indicating that this cytokine is not only a regulatory molecule for T-cell proliferation, but could also be an autocrine growth factor for thymic epithelium.     

临床胃粘膜活检及胃癌手术标本纤维连结蛋白的定位观察

采用免疫组化及免疫电镜技术对临床胃粘膜活检及胃癌手术标本进行了纤维连结蛋白(FN)的定位观察。结果,FN见于胃粘膜上皮细胞和部分癌细胞内以及各种基底膜、间质中。肠化及异型增生上皮细胞FN染色增强,胃癌细胞和其基膜FN减少缺失且与癌细胞分化程度相关,胃癌间质FN丰富,尤其以癌浸润前缘明显。本文着重讨论了胃癌FN改变与癌细胞生物学特性的关系。     

Primitive Cerebral Tumor with Rhabdoid Features: A Case of Phenotypic Rhabdoid Tumor of the Central Nervous System

The rhabdoid tumor (RT) was first described as an aggressive neoplasm of unknown histogenesis affecting the kidneys of infants and young children, but has since been reported in all ages and in many other primary sites, including the central nervous system. It has been shown, however, that the histologic and cytologic features of RT can be mimicked by many other tumors of known histogenesis. For this and other reasons it remains controversial whether cases of putative extrarenal RT represent the same histogenetic entity as RT of the kidney (RTK), another entity or entities, or merely a diverse collection of unrelated tumors sharing a common morphologic phenotype. The present paper describes a lethal primary cerebral tumor in a 26-month-old Hispanic boy that was composed predominantly of cells exhibiting the “classic” rhabdoid phenotype by light microscopy. lmmunocytochemical and ultrastructural studies disclosed features of primitive neuroglial differentiation not seen in RTK. The findings in this case, as well as evidence from other studies, would seem to support the notion that primary RT of the brain may in fact constitute a morphologic and clinicopathologic entity. However, hat entity likely represents a distinctive type of neuroglial neoplasm, more closely related t o other primitive brain tumors than t o RTK.     

Pigments of the Gastrointestinal Tract: A Comparison of Light Microscopic and Electron Microscopic Findings

It is now apparent that light microscopy and histochemistry failed to identify correctly the nature and composition of pigments in various gastrointestinal tract melanoses. In most instances it was thought that the pigment was melanin or a melanin-like substance. Electron microscopy (EM) and electron-probe energy dispersive x-ray analysis have rectified these errors and have shown the following: in melanosis coli the pigment granules contain lipofuscin; in melanoses ilei the pigment granules may contain either silicates and titanium or hemosiderin; and in melanosis duodeni the pigment granules contain iron sulfide. In melanosis esophagi it is not clear what the pigment is; it could be melanin or lipofuscin.     

Immunolocalization of lamins and nuclear pore complex proteins by atomic force microscopy

The nuclear envelope functions as a selective barrier separating the nuclear from the cytosolic compartment. Nuclear pore complexes (NPCs) mediate nuclear import and export of macromolecules and, therefore, are potential regulators of gene expression. In this study we applied atomic force microscopy (AFM) to visualize the three dimensional (3D) structure of individual NPCs in the absence and presence of two different antibodies, one directed against a pore protein (gp62) and another directed against Xenopus lamin LIII, a component of the nuclear lamina, a filament meshwork localized on the nucleoplasmic side of the nuclear envelope (NE) adjacent to and interacting with NPCs. Using 12-nm gold-labelled secondary antibodies and transmission electron microscopy we could clearly localize the primary single anti-gp62 antibody on NPCs and the primary single anti-LIII antibody between NPCs. Using AFM, the secondary antibodies against anti-gp62 could be detected as particles 7 nm in height on the nucleoplasmic face of NPCs. The secondary antibodies against anti-LIII could be clearly identified between NPCs. The secondary antibodies, attached to a 12-nm colloidal gold particle and visualized on glass, revealed similar shapes and heights as found on NEs. According to the 3D images, the volume of a single gold particle conjugated with secondary antibodies was 10 203 nm³. This volume is equivalent to the volume of 38 IgG molecules associated with one individual gold particle. A similar volume of 11 987 nm³ was calculated from a model assuming that the 150-kDa IgG molecules perfectly cover the spherical gold particle. We conclude that AFM can be used for identifying antibodies or other macromolecules associated with biomembranes.     

The three-dimensional microvascular arrangement around rat dorsal hairs as revealed by scanning electron microscopy

The three-dimensional microvascular arrangement around the dorsal hairs in vascular corrosion casts of adult Wistar rats was studied by scanning electron microscopy. Each anagen dorsal hair was surrounded by a basket-like capillary network, which was supplied by the branches of the subcutaneous artery and drained into the veins continuous with the subcutaneous vein. The capillary network surrounding the anagen dorsal hair was denser at its lower part, and became more sparse at its upper part. Transmission electron microscopy showed that the capillaries around the hair bulb possessed fenestrations. Our findings indicate that the microvascular arrangement around the anagen dorsal hair is so organized as to supply the hair bulb, which is the most important area for hair growth, with abundant blood. This study was presented at the 24th Annual Meeting of the Clinical Electron Microscopy Society of Japan, Okayama, September 17–19, 1992.