A morphologic study of the cardiac conduction system in ungulates, dog, and man: Part II: The purkinje system

Abstract

Sheep, Cattle, and Swine 1.1. 1. A distinct, ventricular Purkinje system has been found in sheep, cattle, and swine. This begins in a node which lies at the top of the ventricular muscular septum, near the posterior part of the central fibrous body in the right side of the heart. The fibers of this node do not have a direct connection with the auricular muscle fibers, but run in strands which spread out over the posterior upper part of the ventricular septum, and even enter the right ventricle. 1.2. 2. Only the anterior part of the node changes abruptly into the characteristic Purkinje cells, which run in strands through the bundle and its main branches, and form a subendocardial and intramuscular network in the ventricles. 1.3. 3. Numerous nerve fibers and ganglion cells form a conspicuous and significant part of the His bundle and its ramifications. 1.4. 4. The bundle, its branches, and the Purkinje network are surrounded by a sheath of connective tissue. Nowhere in the system have we seen the Purkinje cells change into ordinary ventricular muscle. 1.5. Man, Dog, and Horse 1.6. 5. In the horse a vestigial remnant of the Purkinje system is present. 1.7. 6. In the dog and in man the local modifications of structure in the homologous positions do not appear to us to possess the characteristic features exhibited by the conduction systems of sheep and cattle. 1.8. 7. Cells, in human and canine hearts, which are considered by others to be Purkinje elements, have been found in the atrial and ventricular musculature of the hearts of all of the species that we have studied.