  A total dominator coloring of a graph G is a proper coloring of G in which
each vertex of the graph is adjacent to every vertex of some color class. The
total dominator chromatic number of a graph is the minimum number of color
classes in a total dominator coloring. In this article, we study the total
dominator coloring on middle graphs by giving several bounds for the case of
general graphs and trees. Moreover, we calculate explicitely the total
dominator chromatic number of the middle graph of several known families of
graphs.
