Final answer:
Cardiac muscle cells are connected by intercalated discs, which contain gap junctions that allow the rapid conduction of a contraction signal between cells.
Step-by-step explanation:
Cardiac muscle cells are specialized in facilitating rapid conduction of a contraction signal from cell to cell through intercalated discs. These intercalated discs contain desmosomes, specialized linking proteoglycans, tight junctions, and gap junctions. Gap junctions allow the passage of ions between the cells, helping to synchronize the contraction of the muscle cells.