Determines which edges or vertices in a Tissue or DTissue are actually parts of cells. Some cells may have been removed from the tissue (died) but the edges and vertices may not have been deleted from the data structure so they remain. These functions will tell you which are parts of living cells.
EdgesUsed[(D)Tissue] returns a list of the (integer) edge numbers corresponding to the edges in T that are actually parts of cells.
VerticesUsed[(D)Tissue]returns a list of the (integer) vertex numbers corresponding to the vertices in T that are actually parts of cells.