AbstractThe goal of the present study is to examine the level of transforming growth factor-β (TGF-β) in fibroblasts and blood microvessels of the human dermis from the development until deep aging (from 20 weeks’ gestation to 85 years of age), and to determine the role of TGF-β in age-dependent changes in the number of fibroblasts and blood microvessels in the dermis. The contents of TGF-β, proliferating cell nuclear antigen (PCNA), and endothelial cell marker CD31 are assessed with the indirect immunohistochemical technique. The results show an increase in the of the proportion of the fibroblasts stained positive for TGF-β in the dermis from 20 weeks’ gestation until 85 years of age. A greater increase in the percentage of TGF-β positive fibroblasts in the human dermis is observed after birth and after the age of 40 years. The content of TGF-β in the blood microvessels of the human dermis decreases significantly after the age of 41 years. An age-related increase in the proportion of fibroblasts stained positive for TGF-β is associated with an age-related reduction of the total number and the percentage of PCNA positive fibroblasts in the human dermis. An age-related decrease in the content of TGF-β in blood microvessels is accompanied by an age-related decrease in their number in the dermis. An age-related increase in the fibroblast content of TGF-β is associated with an age-dependent decrease in their total number and proliferation in the dermis. The age-related reduction of TGF-β content in blood microvessels of dermis is associated with an age-related decrease in the number of blood microvessels in the dermis.