G. Majno

Presence of modified fibroblasts in granulation tissue and their possible role in wound contraction

Au cours de la contraction du tissu de granulation, de nombreux fibroblastes acquièrent des caractéristiques ultrastructurelles qui les rendent semblables à des cellules musculaires lisses. Il est probable que ces éléments modifiés jouent un rôle dans le processus de contraction des plaies.

Contraction of granulation tissue in vitro: similarity to smooth muscle

Strips of granulation tissue from three different experimental models contract in vitro when treated with substances that induce contraction of smooth muscle. Because the fibroblasts in such tissues have some ultrastructural features typical of smooth muscle, our findings indicate that fibroblasts are able to modulate toward a cell type that is morphologically and functionally close to smooth muscle.

Synovial sarcoma Electron microscopic study of a typical case

A case of histologically typical synovial sarcoma has been studied by means of electron microscopy. The more important findings are: 1. the confirmation at the ultrastructural level of the biphasic pattern of the tumor; 2. the presence of a basal lamina between the “epithelial” and the “stromal” part of the tumor; 3. the presence of specialized junctions in the form of desmosomes or maculae adhaerentes between neoplastic cells; these are mostly seen in the epithelial part of the tumor but are not infrequent among stromal cells, and 4. the existence in the extracellular component of the neoplasm of mostly amorphous material, microfibrils, and thin fibrils without periodicity. Only a few mature collagen fibers are seen.

Intra-arterial Injections of Histamine, Serotonin, or Bradykinin: A Topographic Study of Vascular Leakage

Summary Histamine, serotonin, and bradykinin, injected intra-arterially, cause (in susceptible organs) vascular leakage predominantly from the venules. The vascular segments affected are the same as when the mediators are injected locally. This suggests that the selective response of the venules depends on an intrinsic property of the venular wall, and not on the route whereby the mediator reaches the vessel. In certain organs (brain, cerebellum, testis, Gasserian ganglion) histamine-type mediators are apparently unable to cause vascular leakage.

Fibroblasts of Granulation Tissue: Immunofluorescent Staining with Antismooth Muscle Serum

Summary Human antibody against smooth muscle such as found in patients with autoimmune hepatitis binds to rat fibroblasts in contracting granulation tissue, but not to normal rat fibroblasts. This provides another link between granulation tissue fibroblasts and smooth muscle cells.

Epithelioid sarcoma. A light and electron microscopic study suggesting a synovial origin

Two cases of “epithelioid sarcoma” were studied by light and electron microscopy. In both cases, the tumor consisted of a collagen‐rich fibrous stroma with nests of large epithelial‐like cells with acidophilic cytoplasm, giving the neoplastic tissue a biphasic pattern. The ultrastructural study showed that the tumor cells were of three types: “clear” and “dark” cells (recalling those of the synovium and synovial sarcoma) with distorted nuclei and abundant cytoplasm, and a less common, more immature cell. The histologic and ultrastructural features of the neoplastic cells, as well as those of the ground substance, indicate that the tumor is neither of chrondroid nor of histiocytic origin. The cells of the epithelioid islands are similar to the stromal component of synovial sarcoma. It is suggested that epithelioid sarcoma may be a variant of this tumor.

Endothelial contractionin vivo : A study of the rat mesentery

SummaryElectron microscopic studies have previously shown that histamine-type mediators of vascular leakage induce: (1) the appearance of gaps between venular endothelial cells; and (2) deformation of endothelial nuclei, with multiple deep infoldings. It has been postulated that these changes (and the leakage) are due to contraction of endothelial cells. The present paper has investigated this hypothesis by examining the effects of bradykinin and histamine on living rat mesenteric venules. Within 2–5 minutes after application of the mediator, some endothelial cells began to bulge; obvious bulging lasted for about 5 minutes and then subsided slowly; by 20–30 minutes after application of the mediator, the cells were again flattened. This time-course of bulging and flattening corresponded with the rise and fall in vascular permeability, as shown by carbon labeling. Electron microscopy confirmed the presence of deformed nuclei in such vessels. These observations support the concept that vascular leakage, caused by histamine-type mediators, is dependent upon endothelial contraction.

Carbon Deposition in Bronchial and Pulmonary Vessels in Response to Vasoactive Compounds

Summary and Conclusions After intravenous injection of low doses of collodial carbon into rats, a small number of particles are normally found inside phagocytic vacuoles in endothelial cells of small pulmonary vessels. Histamine-type mediators of inflammation injected intravenously induce carbon labeling of bronchial venules while leaving pulmonary vessels virtually unaffected. Under the same conditions, epinephrine does not affect bronchial vessels but greatly enhances the phagocytosis of circulating particles by the endothelium of pulmonary vessels. This work was supported in part by grants No. 3.356.70 from the Fonds National Suisse de la Recherche Scientifique. We thank Haussman Laboratories for the supply of Ferrum Haussman; Mrs. A. Fiaux and Miss M-C. Armand for technical help; Messrs. J-C. Rümbeli and E. Denkinger for photographic work; Drs. G. B. Ryan and P. V. Taylor for help, advice and criticism during various stages of this work.

The microscope in the history of pathology with a note on the pathology of fat cells

Between the birth of the microscope and the birth of microscopic pathology there is a puzzling gap of almost 250 years. Six reasons have been given to explain it: secrecy of the art, high cost of the apparatus, technical difficulty, the notion that the microscope was a toy, lack of new ideas, neglect by Universities. Suspecting that poor optics must have been another major factor in discouraging microscopy, we placed ourselves in the conditions of an experimenter trying to understand acute inflammation in a transparent tissue shortly before 1830 (i.e. before the invention of Listers achromatic objective and of the condenser). We used a Culpeper-type microscope, and a piece of inflamed omentum, fresh, unfixed and unstained. The resolution proved inadequate to recognize the tissue changes of acute inflammation; and the interpretation of these changes was further complicated by the optical artefact known as “reticular image”. On the other hand, using the same system, we made an observation that is scarcely possible in paraffin-embedded tissues: despite the poor optics of an ancient microscope, we saw cellular blebs arising from adipocytes—possibly a novel finding.