Ultrastructure in Biological Systems, Volume 6: Ultrastructure of the Mammalian Heart focuses on the mammalian heart with some cross-reference to that of other vertebrates, such as birds. This book is divided into four main topics— ultrastructure of ventricular and atrial myocardium; impulse generation and conduction system of the heart; embryologic development of the mammalian heart; and ultrastructure of the innervation of the mammalian heart. In these topics, this publication specifically discusses the sarcotubular system (SR), contractile apparatus, general description of cellular morphology, and physiologic implications of cellular and fiber structure. The origin and cytodifferentiation of heart muscle cells, innervation of the sino-atrial node, and ultrastructure of the sympathetic cervical ganglion are also deliberated. This volume is a good source for biologists and students researching on the ultrastructure of the mammalian heart.