Improvement of three-dimensional (3D) culture conditions, including substrates for cell growth, is needed for various cell-based applications. In this study, we developed hydroxyapatite (HAp) macroporous carriers having several pore size distributions and tried to obtain the findings about the effective pore sizes for the growth and function of hepatoblasts derived from human fetal hepatocytes. Cellular CYP3A4 activity was significantly enhanced when 20% HAp macroporous carrier was used, reaching 1.49 +/- 0.28 pmol/10(6) cells/min of benzyloxyresorufin-O-dealkylation activity, which is comparable to that of primary human hepatocytes from livers of adult donors. Analysis of the pore size (the radius of curvature) distribution of each HAp carrier using a 3D-electron beam surface roughness analyzer revealed two peaks of pore size distribution at 30-40 mu m and 70-80 mu m, respectively. Thirty-five percent of the pores in the 20% carrier had a size distribution within 50-80 mu m. Especially, pores of 70-80 gm were more abundant in the 20% HAp carrier than in the 10% and 30% HAp carriers. These results suggested that a HAp carrier with the pore size distribution of 50-80 mu m might be effective for cell growth and function in human hepatoblasts derived from fetal hepatocytes. (C) 2016, The Society for Biotechnology, Japan. All rights reserved.