Perivascular structures in corrosion casts of the human central nervous system: A confocal laser and scanning electron microscope study

Abstract

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.

A Novel Three‐Dimensional Computer‐Assisted Method for a Quantitative Study of Microvascular Networks of the Human Cerebral Cortex

“…Corrosion cast scanning electron microscopy studies [13, 18, 43, 54 , 55 ] give precise morphologic features, including perivascular structure, but are generally used as a 2D approach insofar as images cannot be easily recorded and treated in the 3 planes of the space as with confocal microscopy [ 40 ]. Microfocal X‐ray computed tomography offers an alternative to casting methods but there is no fully automated image segmentation method that provides the necessary accuracy [ 26 ].…”

“…Some authors [ 54 ] have suggested that the capillary bed is a continuous network arranged parallel to the cortical surface without any functional organization. Others suggest the existence of a regulating system based on observations of perivascular structures and blind endings [ 18 , 55 ].…”

Diversity Within Pericytes

“…64 Given our ability to make vascular casts that resemble pericytes, one may wonder whether there is a correlation between the positions of endothelial cell junctions and pericytes. A fine-tuning function of pericytes in the microcirculation has to be considered.…”

Noninvasive detection of neural progenitor cells in living brains by MRI

“…Pericytes, also known as Rouget cells, vascular SM cells, or mural cells, are a type of multipotent perivascular cell found in small blood vessels (arterioles and capillaries) (6). Pericytes respond to angiogenic stimuli and guide sprouting tubes and exhibit macrophage‐like characteristics.…”