  For partially hyperbolic diffeomorphisms with mostly expanding and mostly
contracting centers, we establish a topological structure, called skeleton{a
set consisting of finitely many hyperbolic periodic points with maximal
cardinality for which there exist no heteroclinic intersections. We build the
one-to-one corresponding between periodic points in any skeleton and physical
measures. By making perturbations on skeletons, we study the continuity of
physical measures with respect to dynamics under $C^1$-topology.
