In vitro differentiation studies. (a) Osteogenic control after 21 days in regular expansion media maintained normal morphology and stain negative for Alizarin Red S (× 100). (b) Osteogenic induction after 21 days shows marked morphological changes and extensive extra cellular calcium deposition as demonstrated by positive Alizarin red S staining (× 100). (c) Haematoxylin and Eosin stain of chondrogenic induced micro pellet showing classical hyaline cartilage morphology with lacunae containing chondrocytes surrounded by extra cellular matrix (× 100). (d) Safranin O staining of glycosaminoglycans in the cartilage matrix (× 100). (e) Adipogenic control culture after exposure to regular expansion media shows maintenance of undifferentiated morphology and minor lipid droplet deposition (× 200). (f) Positive adipogenic induction after culture in adipogenic induction media spiked with 15% rabbit serum as demonstrated by morphological change towards larger cells with marked lipid droplet deposition stained with Oil Red O (× 200).