Scanning electron microscopy of Purkinje fibres of the pig heart.
Scanning electron microscopy (SEM) of Purkinje fibres (P-fibres) from the septal walls and the septomarginal trabecula was performed on deparaffinized sections, the identification in SEM made possible by comparative light microscopy. The myofibrils in P-fibres from the septal walls were arranged in a cart-wheel fashion, whereas P-fibres from the septomarginal trabecula showed a nearly parallel alignment of the contractile material. Z-line ridges resembling the T-tubules of the myocardial fibres were observed in both kinds of P-fibres. The myofibrillar arrangements are discussed in relation to the expected mechanical stress put upon P-fibres in the 2 locations during systolic-diastolic activity. An adaptive function of the contractile material to the mechanical stress is suggested and the possible need of a T-tubular system is discussed.
D000818:Animals; D006329:Heart Conduction System / Q000648:ultrastructure*; D006346:Heart Septum / Q000648:ultrastructure*; D008855:Microscopy, Electron, Scanning; D009210:Myofibrils / Q000648:ultrastructure; D011690:Purkinje Fibers / Q000648:ultrastructure*; D012519:Sarcoplasmic Reticulum / Q000648:ultrastructure; D013552:Swine