Macroscopic and Microscopic Studies on Moderator Bands in the Heart of Ostrich (Stuthio camelus)

The wall of the ventricle bears septomarginal trabeculae (moderator band) which extend from the interventricular septum to the opposite wall. These are partly muscular and partly tendinous and vary in different subjects. For study of the moderator band, 12 hearts of the ostrich were collected and the right and left ventricles of each heart were opened. This study revealed that moderator bands found in both right and left ventricles in the ostrich heart in different location. Two types of these bands were encountered: fibrous and fibromuscular. The right ventricle presents one fibro-muscular moderator band about the base of ventricle and small multiple strands as network near the apical region of ventricle. In the left ventricle some present between trabeculae carneae and some extend from interventricular septum to parietal wall. For histological study, specimens of moderator bands from both ventricles were separated. Routine paraffin sectioning with special staining and transmission electron microscopy method were performed. Histological examination showed that fibro-muscular band is composed of cardiac muscle in different ratio, blood vessels, connective tissue and purkinje cells. A fibrous moderator band was like fibro-muscular, but lacks cardiac muscle. These bands are suggested to be radiation of the His bundle. Purkinje cell was pale oval cells which have little myofibrils, cellular organelles and glycogen. They had intercellular junction with each other.