The distensibility of mesenteric venous microvessels

Summary In 20 experiments the distensibility characteristics of venous microvessels of 22–148 m internal diameter in response to arterial and venous pressure changes were examined microphotographically in the isolated and perfused mesentery of the dog. Over a range of arterial pressure between 0 and 170 mm Hg venular diameter changed by 31,8±8,8% and venular length by 6.3±4.4%. Venular length changes were significantly correlated to corresponding changes in the accompanying arterioles, whereas no correlation could be found between changes of length and diameter and the control diameters. With venous pressure elevation from 0 to 30 mm Hg an increase of the volume of venous microvessels of about 360% was measured; beyond a venous pressure of 30 mm Hg a limitation of distensibility was observed in these vessels. The moduli of volume elasticity calculated from these data were lower than the moduli reported for the total venous vasculature of the intestinal bed in the range of physiological pressures. It is concluded that the venous microvessels represent the most distensible elements of the venous vascular system.     

Continuous measurement of venous diameter by a combined photoelectric-photographic and plethysmographic technique

Summary The combined photoelectric-photographic and plethysmographic technique allows for the investigation of the distensibility characteristics and pharmacological influence on the capacitance vessels in an uniform vascular bed (skin veins of the isolated rabbit ear). Diameter changes of a vein segment are recorded continuously by means of a photoresistor and are photographed for calibration. Volume changes of the tissue are measured by a water filled plethysmograph and can be compared with diameter changes of the selected vein segment. The method allows for better interpretation of the results obtained by the plethysmographic technique. In particular, it is possible to distinguish between outward filtration and stress-relaxation.This research was supported by Contract, F 44620-71-C-0117 of the USAF School of Aerospace Medicine, European Office of Aerospace Research (OAR) United States Air Force and Deutsche Forschungsgemeinschaft     

Radial and longitudinal distensibility of arterial microvessels in the mesentery and their dependence on extravascular structures

Summary The distensibility characteristics of arterial microvessels were measured in isolated and perfused segments of canine mesenteric membrane. Pressure-diameter-relations were found to be concave to the pressure axis with a plateau of unchanging diameter seen in approximately 50% of the vessels at pressures above 70 mm Hg. The total change of diameter averaged approximately 15% over the pressure range between 0 and 170 mm Hg. Changes of vessel length (on average 15%) were observed in those vessels which were not fixed at their maximum length by the surrounding connective tissue fibres. A correlation was found between the changes in length and the changes in diameter, indicating that both are influenced by the mechanical properties and the tension in the extravascular structures. The modulus of volume elasticity of arterial microvessels not fixed at constant length was found to increase with increasing pressure, reaching values of approximately 1.0·10⁶ dynes/cm² at a perfusion pressure of 100 mg Hg; for vessels with constant length values of up to 4.0·10⁶ dynes/cm² were obtained. It is concluded that the peripheral microvessels exhibit a greater stiffness than larger arteries and in part derive their mechanical properties from the properties of the surrounding tissues.Partially presented at the 38. Meeting of the German Physiological Society, Erlangen, 1970 [Pflügers Arch.319, R 34 (1970)].     

Mechanical characteristics of skin and underlying tissues in vivo

This paper is concerned with the mechanical characteristics of the complex composite of skin and subcutaneous tissues as they relate to the development of soft tissue replacements. Following a review of previous work and a summary of theoretical considerations, the results of a series of in vivo experiments aimed at quantifying the stiffness of skin and underlying tissues are reported. Variations in compressive properties with age, sex and body site are explained in terms of differences in anatomy and tissue structure.     

Selective double staining of interstitial cells of Cajal and macrophage-like cells in small intestine by an improved supravital methylene blue technique combined with FITC-dextran uptake

Summary By a brief exposure of small intestine (mouse, rat, guinea pig) to lysolecithin prior to vital methylene blue staining we were able to demonstrate in a selective way the complete network of interstitial cells of Cajal, located in the space between the longitudinal and circular muscle layers. A combination with fluorescence labeling (FITC-dextran uptake) of macrophage-like cells, allowed us to demonstrate 1) the complete, regular distribution of both cell populations along the entire small intestine, and 2) the constant, intimate associations between interstitial cells of Cajal and macrophage-like cells.In relation to current hypotheses concerning a role of interstitial cells of Cajal in motility regulation, our results call attention to the possible involvement of another cell type, the macrophage-like cell.A preliminary account of this study was published in the proc. of The XIth Symp. Gastrointest. Motil., Oxford, 1987, in: Digest. Dis. Sci. 32:922     

Immunohistochemical study of epidermal Langerhans cells and dermal dendritic cells in benign and malignant skin lesions characterized by a dermal lymphoid infiltrate consisting either of B-cells or T-cells

Summary Skin biopsies from 43 patients with a rather dense dermal lymphoid infiltrate of either inflammatory or neoplastic nature have been investigated. We studied the number, distribution and immunophenotype of epidermal Langerhans cells and dermal dendritic cells. As previously reported, differences in epidermal Langerhans cell and dermal dendritic cell numbers between skin biopsies with a B-cell infiltrate and skin biopsies with a T-cell infiltrate were found, dendritic cells being more numerous in the latter. The main finding of this study was an uneven distribution of epidermal Langerhans cells and dermal dendritic cells in skin biopsies with a T-cell infiltrate: in skin lesions with an inflammatory lymphoid infiltrate, small clusters of epidermal and dermal dendritic cells admixed with T-lymphocytes (predominantly T-helper/inducer cells) and small blood vessels were present at areas of exocytosis. In skin lesions with a neoplastic lymphoid infiltrate larger, more loosely arranged aggregates of dendritic cells and T-cells were seen. These cell aggregations composed of activated (inflammatory or neoplastic) T-cells and dendritic cells may represent the cutaneous homologue of the secondary T-nodule in the lymph node. Both types of cell aggregates may correspond to the dendritic cell-T cell clusters observed in in vitro induced immune responses.Presented at the XVIth International Congress of the International Academy of Pathology and 7th World Congress of Academic and Environmental Pathology in Vienna, 1986Aspirant of the NFWO (Nationaal Fonds voor Wetenschappelijk Onderzoek)     

Intratubular germ cell neoplasia of unclassified type occupying the whole testis accompanied by a small mature teratoma and metastatic choriocarcinoma and Sertoli cell-only tubules in the other testis

A 19-year-old man with mild mental retardation was diagnosed as having metastatic choriocarcinoma and a testicular tumor. Histopathological examination of the resected testis revealed the presence of a small lesion of mature teratoma but no trace of choriocarcinoma. The remaining seminiferous tubules were atrophic and lined by large atypical germ cells, which were diagnosed as intratubular germ cell neoplasia of the unclassified type (IGCNU). A small area with prominent tubules was also observed. Within this lesion, the tubules were dilated and contained several layers of cells with central necrosis. Immunohistological comparison of staining for several biological markers (Ki-67, c-kit and placental alkaline phosphatase) between cells in the atrophic tubules and those in the dilated tubules indicated a progression of the latter cells to cells with a more proliferative ability. In the opposite testis, examined at autopsy after death due to metastatic choriocarcinoma, all seminiferous tubules were lined by Sertoli cells only. It was therefore assumed that the germ cell tumor of the combined histological type had primarily arisen in the background of IGCNU, and that choriocarcinoma had spontaneously regressed. The early onset of these testicular neoplastic lesions strongly indicates their occurrence under the genetic background of gonadal dysplasia, the Sertoli cell-only syndrome. The possible relation of gonadal disease to mental retardation in this patient is also discussed.