ULTRASTRUCTURAL CHARACTERISTICS OF BLOOD-VESSELS IN THE INFANT AND ADULT HUMAN CEREBRAL-CORTEX

Blood vessels in frontal and temporal cerebral cortex of adults and tw o infants aged 5 months and 5 years were studied by electron microscop y. The cells outside the endothelium were classified on their ultrastr uctural characteristics. Fibroblasts had prominent rough endoplasmic r eticulum and few mitochondria in the cytoplasm. They were different fr om pericytes, which contained a prominent Golgi apparatus but only a f ew, isolated profiles of rough endoplasmic reticulum. Smooth muscle ce lls were distinguished from fibroblasts and pericytes by the presence of filaments and caveolae. Perivascular cells were characterised by th e presence of lysosomes and granules of different sizes and electron d ensities, and were present at all ages studied. Plasma cells had abund ant rough endoplasmic reticulum in the cytoplasm, and were present onl y in the 5-month-old infant cortex. Cortical vessel diameter increased with age.