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.

Timing bone fractures is one of the main tasks of a forensic anthropologist, but still an uncertain diagnostic. In the literature, there are many macroscopic methods to distinguish perimortem from postmortem fractures, based on the distinct structural and mechanical properties of fresh and dry bones. However, this differentiation is still challenging, in particular when the bones are fragmented or still exhibit fresh properties. Although histologic analysis is often used as a complementary diagnostic tool in forensic pathology, its application in the evaluation of bone fractures is uncommon. The aim of this study was to investigate whether fractures of fresh bones reveal a distinct microcracking pattern compared to fractures of dry bones, in order to optimise the fracture timing. To this purpose, we histologically analysed perimortem and postmortem fractures in human humeri. The fresh bones were retrieved from traumatic autopsy cases, and the dry bones from donors which were experimentally fractured. Our results showed that the highest density and length of microcracks (MCKs) were found in the interstitial area of dry fractured bones, which may be considered a marker of postmortem damage. In fresh fractured bones, we generally observed a lower density of MCKs, but a higher proportion of osteonal MCKs, which may be considered a marker of perimortem trauma. In summary, the results of our exploratory study suggest that changes in intrinsic bone factors (mineral/organic components) result in a different microcracking pattern that can be used in fracture timing.

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.