title: Studies of the triad. II. Penetration of tracers into the junctional gap.
abstract: Ferritin and Imferon molecules were introduced as tracers inside "skinned" muscle fibers to test which part of the triadic junction gap is freely exchangeable with the sarcoplasm. At least 50% of the T-system surface is freely accessible from the sarcoplasm. Of the remainder, 30% of the total T-system surface is covered by the junctional feet, and 20% in the center of the junction may or may not be accessible. The possibility is discussed that the triadic junction may not function as an electrical coupling.
mesh_terms: D000818:Animals; D001001:Anura; D004553:Electric Conductivity; D004594:Electrophysiology; D005293:Ferritins / Q000494:pharmacology*; D006651:Histocytochemistry; D007505:Iron-Dextran Complex / Q000494:pharmacology*; D008854:Microscopy, Electron; D009210:Myofibrils / Q000187:drug effects*; D013194:Staining and Labeling
chemical_list: D007505:Iron-Dextran Complex; D005293:Ferritins