Made by branched and elongated cells (nearly 15 nm diameter and 85-100 µm long), myocardium is the heart's muscle. These cells belong to a specific group of muscular tissue – cardiac muscular tissue – and are characterized by:
Having complex intercellular junctions that keep them tight together;
Having transversal striations like skeletal muscular tissue;
Having intercalated discs, transversal lines that get intensively coloured and show up in irregular spaces. These discs are junctional centres in the limit between two cells next to each other and have two forms of presentation: we can see it as straight lines or stairs alike form; in the last form it’s possible to differentiate the transversal region, that is perpendicular to the fibres and the lateral region that is parallel to the same fibres. These structures have three main specialized junctions: coherency zonule where are the actin filaments and sarcomeres, desmosomes that unify the cells preventing that they separate during the muscular activity, and, finally the gap juntions responsible for the ionic continuity of neighbour cells once the contractile sign passes in an ionic wave from a cell to another;
The tissue is involved by a thin sheath of conjunctive tissue with a dense net of capillary vessels.