We studied the morphology of cortical microvessels in the brains of 10 patients who had died after receiving a traumatic head injury (THI). Scanning electron microscopy (SEM) of vascular corrosion casts, confocal microscopy of histological sections after immunocytochemistry, and detection of apoptosis by terminal dUTP nick end labeling (TUNEL) were used. Microvascular casts showed an angioarchitectonic distribution that was defined as normal according to results obtained in a previous, nontraumatic series of subjects. However, when we compared them with previous works, the cast surface of some of the microvessels showed three types of morphological alterations: longitudinal folds, sunken surfaces with craters, and a significant flattening with reduction of lumen. The vessels that were primarily affected were the arterioles and capillaries of the middle and deep cortical vascular zones. Immunostaining with the monoclonal antibody MAS-336 against endothelial cells also showed the presence of longitudinal folds with a thinning of the vascular lumen, cytoplasmic round bodies, and a thickening of the endothelial cell membrane. The TUNEL technique revealed a positive staining of some endothelial cells.The structural alterations we observed indicate that microvessels undergo endothelial cell damage after THI. We suggest that this kind of lesion and the secondary functional injury to the blood-brain barrier (BBB) could play an important role in the development of the secondary lesions that these patients show in the subacute phase. Anat Rec Part A 273A: 583-593, 2003.

Background:The human cerebral cortex is supplied by vessels that arise from the pial arteries. These vessels give rise to a dense vascular network that is highly interconnected. Cortical arteries have been classified in different categories. Both their angioarchitectonic pattern and anatomical structures involved in their regulation are not fully understood.Methods: Twelve fresh human brains were studied by scanning electron microscopy of vascular corrosion casts.Results: Four types of arterial vessels in the cerebral cortex-short, middle, long, and transcortical-were identified. The cortical vascular network was formed by several interconnected clusters of vessels, which were arranged in four vascular layers parallel to the pial surface and characterized by different vascular densities. The greatest vascular density corresponded to the middle and deep vascular layers. Circular constrictions were found at the origin of cortical arteries and at their branching sites, probably related to vascular sphincters. Connections between cortical arteries were observed at their initial course. Plastic strips, occasionally related to constrictions, were observed around both middle and long cortical arteries. Other plastic structures, morphologically similar to pericytes, were found around capillary vessels.Conclusions: The blood supply to the human cerebral cortex depends on the short, middle, and long cortical arteries, which give rise to a highly anastomosed capillary network. There exist vascular connections between pial arteries and occasionally between cortical arteries. Blood flow autoregulation is probably mediated by smooth muscle cells at the arteriolar level and by pericytes at the capillary level, through endothelial connections. Anat. Rec. 251:87-96, 1998.

Background:The human cerebral cortex is supplied by vessels that arise from the pial arteries. These vessels give rise to a dense vascular network that is highly interconnected. Cortical arteries have been classified in different categories. Both their angioarchitectonic pattern and anatomical structures involved in their regulation are not fully understood.Methods: Twelve fresh human brains were studied by scanning electron microscopy of vascular corrosion casts.Results: Four types of arterial vessels in the cerebral cortex-short, middle, long, and transcortical-were identified. The cortical vascular network was formed by several interconnected clusters of vessels, which were arranged in four vascular layers parallel to the pial surface and characterized by different vascular densities. The greatest vascular density corresponded to the middle and deep vascular layers. Circular constrictions were found at the origin of cortical arteries and at their branching sites, probably related to vascular sphincters. Connections between cortical arteries were observed at their initial course. Plastic strips, occasionally related to constrictions, were observed around both middle and long cortical arteries. Other plastic structures, morphologically similar to pericytes, were found around capillary vessels.Conclusions: The blood supply to the human cerebral cortex depends on the short, middle, and long cortical arteries, which give rise to a highly anastomosed capillary network. There exist vascular connections between pial arteries and occasionally between cortical arteries. Blood flow autoregulation is probably mediated by smooth muscle cells at the arteriolar level and by pericytes at the capillary level, through endothelial connections. Anat. Rec. 251:87-96, 1998.

Scanning electron microscopy (SEM) of microvascular corrosion casts revealed perivascular structures that resembled smooth muscle and pericyte cells. Although these structures have been studied in widely different experimental contexts, their origin, function, and distribution pattern in different tissues are not understood. Microvascular corrosion casts from 15 fresh human brains and 20 lumbar spinal cords were studied by SEM. In five cerebral hemispheres a fluorescent resin was injected in order to study the vascular bed by confocal laser scanning microscopy (CLSM). Microvascular casts showed two perivascular structures on their surfaces: plastic strips, which formed a muff around arteriolar vessels, and pericyte-like structures that were present around the capillary network. Their morphological characteristics and distribution were similar to those of smooth muscle cells and pericytes, respectively. The SEM study showed that these structures were not tightly joined to the cast surface, but were connected to the vascular cast by narrow plastic connections. The CLSM showed that the resin invaded the subendothelial space, thus giving rise to these structures. Perivascular structures associated with arteriolar and capillary vessels appear to represent smooth muscle cells and pericytes. They are formed by the passage of the resin to the subendothelial space, probably through weak endothelial cell junctions. The effusion of resin into the subendothelial space may represent evidence for the structural basis of myocyte and pericyte cell control. Chemical communication by substances released locally or transported to these cells through these junctions may regulate their functions, allowing them to regulate blood flow.

Scanning electron microscopy (SEM) of microvascular corrosion casts revealed perivascular structures that resembled smooth muscle and pericyte cells. Although these structures have been studied in widely different experimental contexts, their origin, function, and distribution pattern in different tissues are not understood. Microvascular corrosion casts from 15 fresh human brains and 20 lumbar spinal cords were studied by SEM. In five cerebral hemispheres a fluorescent resin was injected in order to study the vascular bed by confocal laser scanning microscopy (CLSM). Microvascular casts showed two perivascular structures on their surfaces: plastic strips, which formed a muff around arteriolar vessels, and pericyte-like structures that were present around the capillary network. Their morphological characteristics and distribution were similar to those of smooth muscle cells and pericytes, respectively. The SEM study showed that these structures were not tightly joined to the cast surface, but were connected to the vascular cast by narrow plastic connections. The CLSM showed that the resin invaded the subendothelial space, thus giving rise to these structures. Perivascular structures associated with arteriolar and capillary vessels appear to represent smooth muscle cells and pericytes. They are formed by the passage of the resin to the subendothelial space, probably through weak endothelial cell junctions. The effusion of resin into the subendothelial space may represent evidence for the structural basis of myocyte and pericyte cell control. Chemical communication by substances released locally or transported to these cells through these junctions may regulate their functions, allowing them to regulate blood flow.

The majority of studies as to whether gastric and nongastric factors are involved in the ' rotation ' of the human embryonic stomach around its longitudinal axis have been morphological. The aim of this study was to analyse, with morphometric support, the influence on the angular modifications during gastric rotation of the simultaneous changes of the gastric walls and mesenteric growth, and the volumes of organs adjacent to the stomach (right, left and posterior groups). Computer imaging techniques were applied on cross sections of a graded series of 10 human embryos (from Carnegie stage (CS) 11) and 2 fetuses. A clockwise gastric rotation occurred during the embryonic period. The most rapid angular modifications took place from CS 11 to 16, after the rotation became oscillatory with angular changes in clockwise and anticlockwise directions, reaching the highest value at CS 18 (at the supraomental part of the stomach : 54.37m ; at the omental part : 68.03m) ; after this period the angular values tended to stabilise. The predominant growth of the left gastric wall over the right and the changes in the width of the gastric mesentery were the most persistent factors involved in the modifications of the transverse gastric angle during the embryonic period although without relationship to their direction. During the increasing angular phases, clockwise rotation was promoted by the decrease of the volume of any group of organs adjacent to the stomach. When the volume of the left and posterior groups increased simultaneously, clockwise or anticlockwise angular directional change was related to the respective decrease or increase adjacent organ volume to the right. We conclude that the stomach of the human embryo undergoes heterogeneous and multifactorial rotation as a consequence of the overall increase in gastric wall growth to the left and the increase of gastric mobility produced by the previous mesenteric enlargement, and that the rotational direction results from the forces exerted on the stomach and the gastric mesenteries by the adjacent organs.

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