Fig. (4) The image shows two clusters, a small one with extensive
BMP 2/4 expression at the right side and a larger one with poor
BMP 2/4 expression on the left side. Because of high BMP
expression, vital cells and a small rim of neo-matrix the right
cluster was considered to be a young cluster. The left one with the
large amount of non-vital cells, poor BMP expression and the large
rim of neo-matrix was considered to be a mature cluster (BMP 2/4,
400x).