SEM and EDX investigation of merged human pulp cell spheres in a human root canal. Figure (a) shows a fibrillar surface of the closed cell construct with different sized mineral like structures on it (Figure 4b) by detection of secondary electrons. The white arrows in figure (b) represent a cellular connection between the mineral particles and the underlying cell layer. The images in figure (c) and (d) show the same areas investigated by the detection of back scattered electrons with a clearly seen atomic number depending material contrast between the spheres’ cell matrix and the mineral particles. Black asterisks in figure (b) and (d) denote particles with higher atomic numbers, which could only be seen in figure (d) by the aid of the material contrast. The area of the sphere, which was investigated by EDX, is marked with black lines in figure (e). The results concerning the higher concentration of mineral specific elements are represented in figure (f) (phosphate) and figure (g) (calcium).