title: Light and electron microscopic structure of the cardiac Purkinje fibers--review.
abstract: The history and the morphological characteristics of the Purkinje fibers are reviewed briefly in different species and in the atrioventricular (A-V) bundle branches (BB) of the same species. The so-called typical Purkinje fibers corresponding to the original description are found in birds, ungulates, and larger mammals. The specialized fibers of the ventricular impulse conduction are present, however, in all mammals and are distinguishable with new and reviewed morphological methods from the force-producing fibers. The Purkinje fiber term is applicable for all the BB fibers, which, by their morphology, might be classified in man and small mammals as Purkinje I (proximal BB), II (ramified BB), and III (terminal) fibers. The main characteristics of the Purkinje fibers are: cable-like structure in birds, ungulates, and proximal BB fibers of other mammals; lack of transverse tubular system; generally little contractile material associated with a high number of intermediate filaments; few mitochondria and low mitochondrial enzyme activity; high amount of glycogen and anaerobic ability rendering them relatively resistant to hypoxia. The distribution of the Purkinje net-work and the modes of Purkinje and ventricular fiber interconnections are also reviewed.
mesh_terms: D000818:Animals; D001001:Anura; D002645:Chickens; D006168:Guinea Pigs; D006329:Heart Conduction System / Q000166:cytology*; D006801:Humans; D008322:Mammals; D051379:Mice; D008854:Microscopy, Electron; D011690:Purkinje Fibers / Q000166:cytology*; D051381:Rats