Abstract
Muscle cells of rat rectus abdominus and diaphragm were mordanted in tannic acid and ultrathin sections, after staining with lead citrate, showed a variable but usually marked increase in electron density of T-tubules, subsarcolemmal caveolae and, to a lesser degree, the plasmalemma, basal lamina material, and associated collagen microfibrils. The technique permits clear demonstration of continuity of the membranes of T-tubules and caveolae with the sarcolemma. While some T-tubules open directly into the extracellular space, others do so indirectly via a caveola. The T-tubules show some variation in diameter and not all are transverse in orientation; they frequently branch, reunite, and run longitudinally, often connecting T-tubules of adjacent triads across a Z-line. Subsarcolemmal caveolae (approximately 100 nm diameter) line the sarcolemma in a single row and show frequent connections by narrow tubules to form dumbell, trefoil, and four-leafed profiles.The findings lead to the conclusion that both T-tubules and caveolae are open to the extracellular space and that T-tubules open both directly and indirectly via caveolae to the surface.
Publisher
Canadian Science Publishing
Subject
Animal Science and Zoology,Ecology, Evolution, Behavior and Systematics
Cited by
5 articles.
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