The perivascular fibrotic reaction in rat brain in the late period after experimental clinical death. II. Precapillary vessels.

The aim of the study was to investigate the area surrounding precapillary vessels in the temporal cortex of rat-brains. The material consisted of animals that survived a 10-minute cardiac arrest and then lived on for 10 to 12 months. In the specimens that survived 10 month we observed dilatation of the pericapillary space pervaded with unidentified cells surrounded by multiple collagen fibrils. In the close vicinity of these vessels we often discerned cells participating in the process of phagocytosis. Smooth muscle cells held numerous pinocytic vesicles which contained microfibrillar material. Collagen fibrils were also discerned beneath their basement membrane. In the animals that survived 12 months in many cases the spaces between blood vessel mural myocytes and brain cells were filled with numerous collagen fibrils. In some cases these fibrils formed bridge-like structures between vessel walls and surrounding nerve cells. These compartments were often accompanied by brain phagocytes, the cytoplasm of which contained single fibres or bundles of collagen located in the close proximity of the phagolysosomes. We discussed the role of myocytes, myofibroblasts and phagocytes in the production of reparative collagen following the destruction of precapillary vessels and brain continuity.