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  • 1
    Electronic Resource
    Electronic Resource
    Scanning electron microscopy of esophageal microvasculature in human infants and rabbits (1992)
    Springer
    Anatomy and embryology 186 (1992), S. 33-40 
    Details
    ISSN: 1432-0568
    Keywords: Esophagus ; Human infants ; Rabbit ; Microvascularization ; Corrosion casts ; Scanning electron microscopy
    Source: Springer Online Journal Archives 1860-2000
    Topics: Medicine
    Notes: Summary The microvasculature of the esophagus was studied by scanning electron microscopy of vascular corrosion casts in human infants and rabbits. In both species, segmental circumferential arteries arise from main longitudinal arteries, the latter giving off numerous perforating arteries. The tunica muscularis is supplied by branches of circumferential and perforating arteries, the submucosa and its glands by branches of perforatings. Terminal arborizations of perforating arteries feed a subepithelial capillary network. These capillaries are drained by a venous plexus in the lamina propria which is connected to a submucosal venous plexus. Perforating veins, running parallel to the corresponding arteries, connect the submucosal plexus with circumferential veins, and finally empty into main longitudinal veins. Valves were not present in any of the veins. Submucosal veins were less numerous in man than in rabbit. The number and caliber of equivalent vessels in human submucosal plexus decreased from the pharyngoesophageal to the gastroesophageal junction, suggesting the latter to be at particular risk in portal hypertension. The subepithelial capillary network reveals a longitudinal arrangement in rabbits, while the same network shows no preferential organization in human infants. The microvascular architecture of the esophagus in humans and rabbits is comparable, especially in the lay-out of the venous plexuses and the absence of venous valves. Therefore the rabbit could serve as an experimental model for studies on portal hypertension. The present results strongly suggest particular significance of the venous plexus in the lamina propria for the genesis of esophageal varices.
    Type of Medium: Electronic Resource
    URL: http://dx.doi.org/10.1007/BF00710400
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  • 2
    Electronic Resource
    Electronic Resource
    Sphincters of canine hepatic sublobular veins respond to endothelin-1 and 3 (1997)
    Springer
    Anatomy and embryology 196 (1997), S. 299-309 
    Details
    ISSN: 1432-0568
    Keywords: Key words Liver ; Veins ; Circulation ; Endothelin ; Corrosion casting
    Source: Springer Online Journal Archives 1860-2000
    Topics: Medicine
    Notes: Abstract  The dog has been used repeatedly as a model in liver transplantation research. The microcirculation and its regulatory mechanisms play a crucial role during ischemia and reperfusion. Little is known about the role of venous sphincters in regulating blood flow in the dog liver. Hence, we performed this study to elucidate their potential role in regulating local blood flow. In 14 dogs mean systemic (MSP) and mean portal venous pressure (MPP) were measured. Light and electron microscopy (scanning and transmission) of tissue sections and vascular corrosion casts were used to elucidate the microvascular morphology. Immunocytochemistry was applied to identify smooth muscle cells and the innervation of venous sphincters. Endothelins 1 and 3 were injected to find whether the hepatic venous sphincters are sensitive to these vasoactive agents. Tufts of smooth muscle cells were found in the sublobular veins (SLV; 100 to 250 µm in diameter), that reduced the luminal diameters of veins by 34%. Nerve endings were not observed close to these venous sphincters. The MSP and MPP were 75.3±2.4 mmHg and 8.9±0.95 mmHg, respectively. Treatment with 1.0 µg/kg of endothelin-1 (ET-1) significantly increased the MSP, the MPP and the percentage of focal venous sphincter contraction by 39% (105±4.7 mmHg), 43% (12.8±1.7 mmHg) and 57% (53.5±4.7), respectively (P 〈0.01). Treatment with ET-3 caused a significant (P 〈0.01) decrease in the MSP, the MPP and the percentage of sphincter contraction by 19% (61.0±2.2 mmHg), 39% (5.8±2.9 mmHg) and 38% (20.9%±3.15). Sinusoids did not contain sphincters. Hepatic arterioles and central veins were not affected by ET-treatment. The contraction of SLV sphincters correlated with increases in MPP (r=0.81, P 〈0.01) and was related to the MSP (r=0.67, P 〈0.01). These data show that the smooth muscle sphincters in SLV of the dog liver are involved in the local regulation of blood flow and that these sphincters are stimulated by non-neurogenic mechanisms. These sphincters contract in response to ET-1 and relax in response to ET-3. Since ET-1 is released during and/or causes inflammation, e.g., during ischemia and reperfusion, its antagonists might be of benefit during transplantation reperfusion of liver.
    Type of Medium: Electronic Resource
    URL: http://dx.doi.org/10.1007/s004290050099
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  • 3
    Electronic Resource
    Electronic Resource
    Pulmonary lymphatic filling is increased in spontaneously hypertensive rats (1999)
    Springer
    Anatomy and embryology 200 (1999), S. 425-432 
    Details
    ISSN: 1432-0568
    Keywords: Keywords Pulmonary veins ; Lymphatics ; Corrosion casting ; Scanning electron microscopy ; Pulmonary edema
    Source: Springer Online Journal Archives 1860-2000
    Topics: Medicine
    Notes: Abstract  Extravascular lung liquid must rely on tissue-space pressure gradients to drive it into the lymphatics because the fluid is outside the lymphatic contractile pumping and valve control. Focal tissue pressure changes could result from muscular contraction in the blood vessel walls. Perivascular lymphatics usually lie within the adventitia of pulmonary blood vessels, and are generally more noticeable in veins than arteries. Spontaneously hypertensive rats have exaggerated focal pulmonary venous muscle (venous sphincters). These muscular tufts are often near initial lymphatics; if their contraction was important for lymph transport, spontaneously hypertensive rats could have more lymphatic filling in the areas of the pulmonary venous sphincters than normotensive rats. Because the focal muscularity is found in pulmonary veins more than arteries, veins may have more focal lymphatic filling than arteries. To test these hypotheses, lung histology and vascular and lymphatic casts of spontaneously hypertensive and normotensive rats were examined. Contracted venous sphincters were found on 108 of 127 veins with lymphatics in the spontaneously hypertensive rats and 5 of 41 in the normotensive rats P〈0.01). The spontaneously hypertensive rats had deeper venous contractions and more lymphatic filling around both arteries and veins (P〈0.01). In the hypertensive rats, the venous was greater than the arterial lymphatic filling (P〈0.01). On the pleural surface, hypertensive rats also had greater lymphatic filling than controls (P〈0.01). This anatomic evidence suggests that pulmonary venous sphinters are associated with focal lymphatic filling, and perivascular muscle action might be a component of the pulmonary lymphatic system.
    Type of Medium: Electronic Resource
    URL: http://dx.doi.org/10.1007/s004290050292
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  • 4
    Electronic Resource
    Electronic Resource
    The cochlear glomeruli in the modiolus of the guinea pig (1993)
    Springer
    European archives of oto-rhino-laryngology and head & neck 250 (1993), S. 44-50 
    Details
    ISSN: 1434-4726
    Keywords: Cochlear glomeruli ; Guinea pig ; Corrosion casting ; Electron microscopy
    Source: Springer Online Journal Archives 1860-2000
    Topics: Medicine
    Notes: Summary The cochlear glomeruli were studied in guinea pigs using scanning electron microscopy of vascular corrosion casts and transmission electron microscopy of tissue sections. Two types of coiled vessels forming the cochlear glomeruli were found in the bony wall of the modiolus. First, upper glomeruli were seen situated in the bony wall next to the scala vestibuli; second, lower glomeruli were located in the osseous spiral lamina just above the spiral ganglion. Upper glomeruli gave rise to radiating arterioles which supplied capillaries of the stria vascularis, while lower glomeruli fed the capillaries of the spiral lamina and limbus. Unlike the main supplying arteries, smooth muscle cells were not present in the walls of the arterioles forming the glomeruli and a peculiar layer of lamellar pericytes was found. The arterioles were strikingly longer than their parent vessels and no autonomic nerves were found in close spatial relationship. Hence, these findings indicate that the cochlear glomeruli serve as efficient devices for reducing cochlear blood pressure.
    Type of Medium: Electronic Resource
    URL: http://dx.doi.org/10.1007/BF00176948
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  • 5
    Electronic Resource
    Electronic Resource
    Microangioarchitecture of the guinea pig common bile duct and duodenal papilla: A scanning electron and light microscopic study (1994)
    New York, NY [u.a.] : Wiley-Blackwell
    The @Anatomical Record 239 (1994), S. 280-286 
    Details
    ISSN: 0003-276X
    Keywords: Papilla ; Duodenum ; Microscopy ; Scanning electron ; Corrosion casting ; Microcirculation ; Guinea pig ; Life and Medical Sciences ; Cell & Developmental Biology
    Source: Wiley InterScience Backfile Collection 1832-2000
    Topics: Medicine
    Notes: Background: The microvascular pattern of the duodenal papilla is unknown. Since the duodenal papilla is located in the transition zone between the stomach and duodenum, and because it regulates bile transfer into the duodenum, a particular microangioarchitecture can be expected. Therefore, we examined the microvasculature of the papilla using guinea pigs as a model.Methods: The microvascularization of the duodenal papilla and common bile duct was studied in 26 adult guinea pigs (Cavia porcellus), using scanning electron microscopy of microvascular corrosion casts and critical point dried specimens, and light microscopy of tissue sections.Results: The duodenal papilla is located in the cranial portion of the duodenum, approximately 5 mm beyond the pyloric valve. At the most luminal aspect of the cast papilla, ring-shaped capillaries, resembling those of the cast gastric mucosa, are present. Deeper parts of the papilla are provided with villi. Subepithelial capillaries of the papilla are 15 μm thick in average. These capillaries have a dual blood supply either via the straight long arterioles arising from the submucosa or by the pericryptal capillaries. The common bile duct comprises numerous mucoid glands with their pits surrounded by ring-shaped capillaries in corresponding casts.Conclusions: The special arrangement of different capillary patterns, together with their luminal size and the dual blood supply, favor their protective role from the gastric chyme. © 1994 Wiley-Liss, Inc.
    Additional Material: 16 Ill.
    Type of Medium: Electronic Resource
    URL: http://dx.doi.org/10.1002/ar.1092390306
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  • 6
    Electronic Resource
    Electronic Resource
    Scanning and transmission electron microscopy of venous sphincters in the rat lung (1992)
    New York, NY [u.a.] : Wiley-Blackwell
    The @Anatomical Record 233 (1992), S. 555-568 
    Details
    ISSN: 0003-276X
    Keywords: Life and Medical Sciences ; Cell & Developmental Biology
    Source: Wiley InterScience Backfile Collection 1832-2000
    Topics: Medicine
    Notes: The rat pulmonary microvasculature was studied using scanning and transmission electron microscopy of vascular corrosion casts and tissue sections. Special emphasis was placed on small pulmonary venous vessels. The shape of vascular casts was analyzed and interpreted concerning the wall composition of corresponding vessels studied in tissue sections. On the casts of pulmonary venules and small pulmonary veins, narrow or wider annular constrictions were regularly observed. Within these constrictions, marks of circularly running grooves were seen as an additional structural detail, which obviously mimic impressions of single or grouped smooth muscle cells. The depth of the constrictions varies; it may be more or less pronounced, occasionally narrowing down the luminal diameter to approximately 50%. These constrictions are caused by muscular sphincters. In tissue sections of small pulmonary veins, sphincter regions were identified as abruptly appearing single or grouped true smooth muscle cells. Smooth muscle cells may be arranged side by side in a group or bundle or even staked in two or three layers. Between the sphincter regions, the venous wall consists merely of endothelium and an accompanying connective tissue layer. The smooth muscle cells of a sphincter are regularly positioned between endothelial layer and elastic lamina. The smooth muscle cells next to the endothelium form myoendothelial junctions. Autonomic nerves near the sphincters were never seen. The venous sphincters described are suggested to be effective devices involved in blood flow regulation. Blood-borne substances or local tissue hormones might govern sphincter function. © 1992 Wiley-Liss, Inc.
    Additional Material: 23 Ill.
    Type of Medium: Electronic Resource
    URL: http://dx.doi.org/10.1002/ar.1092330410
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  • 7
    Electronic Resource
    Electronic Resource
    Pulmonary lymphatics and their spatial relationship to venous sphincters (1995)
    New York, NY [u.a.] : Wiley-Blackwell
    The @Anatomical Record 242 (1995), S. 531-544 
    Details
    ISSN: 0003-276X
    Keywords: Pulmonary veins ; Pulmonary circulation ; Corrosion casting ; Scanning electron microscopy ; Pulmonary edema ; Lymphatics ; Rat ; Life and Medical Sciences ; Cell & Developmental Biology
    Source: Wiley InterScience Backfile Collection 1832-2000
    Topics: Medicine
    Notes: Background: Pulmonary lymphatics are critical to clearing lung fluid. Although their structure can be shown with light and transmission electron microscopy, scanning electron microscopy of their casts can better show their number, size, shape, distribution, and degree of filling. This technique has identified four forms of lung lymphatics, but these forms have not been fully evaluated by tissue microscopy. A most important site of pulmonary edema formation, the pulmonary capillary, is just upstream from small veins which have focal, smooth muscle tufts termed venous sphincters. Because of their constricting potential, these sphincters may control lung perfusion and cause edema.Methods: With light and transmission electron microscopy of tissue and scanning electron microscopy of casts, the lymphatic forms were explored in relation to the tissue anatomy in rats without pulmonary edema and with mild-to-moderate edema caused by extended vascular rinsing.Results: The edematous lungs had increased sacculo-tubular lymphatics adjacent to the venous sphincters. These lymphatics were in the adventitial connective tissue and were partially endothelialized. As lymphatics became more tubular their endothelium became more complete. Collagen fibers traversed the lumen of these lymphatics even where endothelial cells were present and caused the lines on the surface of the lymphatic casts. Overlapping endothelial cells caused clefts on the casts.Conclusions: Scanning electron microscopy of lymphatic casts better defines their ultrastructure and shows the spatial relationship of veins and their sphincters to venous lymphatics. Sphincter contraction may influence pulmonary lymph production which could affect other aspects of regional lung perfusion. © 1995 Wiley-Liss, Inc.
    Additional Material: 25 Ill.
    Type of Medium: Electronic Resource
    URL: http://dx.doi.org/10.1002/ar.1092420409
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  • 8
    Electronic Resource
    Electronic Resource
    Mandibular and molar vascularization in guinea pigs. Scanning electron microscopic study of corrosion casts (1990)
    New York, NY [u.a.] : Wiley-Blackwell
    The @Anatomical Record 228 (1990), S. 471-477 
    Details
    ISSN: 0003-276X
    Keywords: Life and Medical Sciences ; Cell & Developmental Biology
    Source: Wiley InterScience Backfile Collection 1832-2000
    Topics: Medicine
    Notes: The vascularization of the mandible, molar teeth, and periodontal ligament of adult male and female albino guinea pigs (Cavia porcellus) was studied by scanning electron microscopy of vascular corrosion casts. Main routes of mandibular blood supply and drainage are shown, and the intrinsic vascular patterns of the mandible, the molars, and the periodontal ligament are described. Results are compared to findings in man and in other mammals.
    Additional Material: 21 Ill.
    Type of Medium: Electronic Resource
    URL: http://dx.doi.org/10.1002/ar.1092280414
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  • 9
    Electronic Resource
    Electronic Resource
    Scanning and transmission electron microscopy and high resolution intravital video-microscopy of capillaries in the mouse exocrine pancreas, with special emphasis on endothelial cells (1993)
    New York, NY [u.a.] : Wiley-Blackwell
    The @Anatomical Record 237 (1993), S. 163-177 
    Details
    ISSN: 0003-276X
    Keywords: Microscopy, Scanning electron ; Microscopy, Transmission electron ; Microscopy, Intravital ; Endothelial contractility ; Exocrine pancreas, Mouse ; Life and Medical Sciences ; Cell & Developmental Biology
    Source: Wiley InterScience Backfile Collection 1832-2000
    Topics: Medicine
    Notes: Capillaries in the mouse exocrine pancreas were studied by scanning electron microscopy of microvascular corrosion casts, transmission electron microscopy of tissue sections, and high resolution intravital video-microscopy. Two types of capillaries were discerned by corrosion casting. The first type was rather straight, had a constant diameter of 5-6 μm, and its surface showed multiple circumferential furrows. The frequency of such constrictions was less in the second type, which was more undulated and had a diameter of 7-9 μm. In the second type, these constrictions defined bulged areas of the capillary cast. Corresponding tissue sections also showed two types of capillaries, fenestrated and non-fenestrated capillaries. Microtubules were abundant in all capillary endothelial cells, whereas bundles of microfilaments were scarce. Microtubules were arranged along the long axis of endothelial cells as well as parallel to endothelial cell border regions. Endothelial cells were joined by intermediate junctions along cell borders running both circumferentially and longitudinally. Flow reversal in capillaries and spontaneous endothelial contractions were documented in vivo. Endothelial cells bulged into the lumen, either at their nuclear region or distant from it. Spontaneous contraction of pericytes was not observed. These results suggest that contraction of capillaries is carried out by endothelial cells, representing an autonomous flow regulatory device. Capillary contraction in exocrine pancreas may be influenced by blood-borne agents, probably by those released in Langerhans islets. © 1993 Wiley-Liss Inc.
    Additional Material: 30 Ill.
    Type of Medium: Electronic Resource
    URL: http://dx.doi.org/10.1002/ar.1092370204
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  • 10
    Electronic Resource
    Electronic Resource
    Microvascular pattern in the metaphysis during bone growth (1995)
    New York, NY [u.a.] : Wiley-Blackwell
    The @Anatomical Record 242 (1995), S. 111-122 
    Details
    ISSN: 0003-276X
    Keywords: Bone ; Metaphysis ; Capillary sprouts ; Corrosion casting ; Light microscopy ; Transmission electron microscopy ; Life and Medical Sciences ; Cell & Developmental Biology
    Source: Wiley InterScience Backfile Collection 1832-2000
    Topics: Medicine
    Notes: Background: Little is known about the three-dimensional micromorphology of vessels in the growth zone of long bones, where significant vasculogenesis occurs. Therefore, we examined the microvascular pattern of the femoral metaphysis.Methods: Six-week-old normal rats of either sex were used. We cast the femurs of 14 rats with Mercox for scanning electron microscopy (SEM), and in 10 rats we prepared tissue sections of femurs for light (LM) and transmission electron microscopy (TEM).Results: In the LM, calcified cartilage was found to define cylindrical compartments beneath the last row of hypertrophied chondrocytes of the metaphyseal growth plate. These compartments ran in the bone's longitudinal axis and contained a single capillary profile. Endothelial cells of these capillaries often showed increased cytoplasmic volume and loose texture of nuclear chromatin. Cast metaphyses by SEM showed numerous parallel vascular loops with nodular protrusions 10-12 μm in diameter at their tips. The loops had ascending and descending limbs with a luminal diameter of 10-14 μm. Small projections 4-5 μm in diameter and delicate crests were sometimes found on the tip of the larger nodes. In a 100 × 100 μm area, there were 14-17 large nodes. By TEM, capillary sprouts were identified at the level beneath the last row of hypertrophied chondrocytes. These capillaries had voluminous endothelial cells rich in free ribosomes and rough endoplasmic reticulum. Endothelial cell nuclei were rounded and showed loose chromatin texture. Endothelial cells were connected by intermediate junctions and there was no basal lamina. Deeper into the metaphysis, arterioles and sinusoids were present.Conclusions: We conclude that the metaphyseal plate of the growing rat offers an optimal model to study vasculogenesis. Capillary sprouts can be readily identified, measured, and counted because they are located within a plane bordering against avascular cartilage. In addition, by using microvascular corrosion casting in SEM not only capillary sprouting per se but also different stages of neovascularization, indicated by differently sized nodular projections at the tip of vascular loops, can be studied in the growing long bone. © 1995 Wiley-Liss, Inc.
    Additional Material: 16 Ill.
    Type of Medium: Electronic Resource
    URL: http://dx.doi.org/10.1002/ar.1092420115
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