Diameter measurement and classification of PFFs. A. PFFs were divided into three groups based on microscopic assessment. PFFs, porcine fetal fibroblasts; S, small; M, medium; L, large. B. Measurement of cell’s diameter. C. Diameter distribution diagrams and pie graph of PFFs. Green, blue and red represent small cells, medium cells and large cells, respectively. D. Verification of reliability of classification method by ninefold replicate operation. The results are presented as the mean±SD. Data are representative of three independent experiments (a, b, cP<0.05)