Bone marrow cells were cultured on in situ photopolymerizable scaffolds based on D,L-lactide and epsilon-caprolactone. The influence of pore volume, size and shape were evaluated. Bone formation was demonstrated by ALP activity, osteocalcin secretion and histological analysis. TEM at the polymer interface revealed osteoblasts which secreted an extracellular matrix containing matrix vesicles loaded with apatite. Cellular infiltration was possible for scaffolds with a porosity of 70 and gelatin particle size of 250-355 microm. Scaffolds with a porosity less than 70 had the tendency to form a polymer top layer. Although increasing the gelatin particle size to 355-500 microm, leads to infiltration even in scaffolds with a porosity of 60. No infiltration was possible in scaffolds with sodium chloride as porogen. On the contrary, sucrose and gelatin leads to better interconnected scaffolds at the same porosity. Hence, spherical gelatin particles are suitable to use as porogen in photopolymerizable scaffolds.