Age-related changes of brain microvasculature. Post-mortem (myocardial acute infarction) histology studies on paraffin-embedded sections (5 μm thick) of formalin-fixed cerebral tissue. PAS staining of human brain gray matter, showing normal capillaries and arterioles in a young (A,C) compared to concentrically thickened microvessels in an aged man (B,D) mostly due to hyalinization (pink staining). Masson's trichrome staining shows normal microvessel in a young (E) and perivascular deposition of collagen (blue staining) around capillaries in an aged man (F). Immunohistochimical analysis for α-SMA shows normal arteriole in a young (G) and concentrically thickened arteriole due to an altered proliferation of smooth muscle cells in an aged man (H). Magnification 40×.