Histochemical study on the dihydrofolatereductase and folic acid in mammalian brain cortex

Histochemical and biochemical studies on the folate metabolism (folic acid an its principal enzyme-dihydrofolate-reductase) in bovine cortex - gyrus marginallis in the process of ageing were performed, in parallel with NADH2-cytocrom-C-reductase (diaphorase). Folic acid and folate enzyme, weak positive in neurons in young age, increased in old age in nerve cells and especially in their processes and in capillaries. The diaphorase strongly increased in all cells, glia and vessels, in old age.