Tubules invaginating from the sarcolemma in the subneural region of muscle fibers.
Sarcoplasmic tubules invaginating from the sarcolemma of the subneural region of muscle fibers are described in Atlantic hagfish and rat. In rat, the tubules invaginate from the bottoms of the secondary synaptic clefts. The density of tubule openings may be higher than the density of T-tubule openings elsewhere along muscle fibers.
D000818:Animals; D006196:Hagfishes; D008297:Male; D008854:Microscopy, Electron; D009469:Neuromuscular Junction / Q000648:ultrastructure*; D051381:Rats; D012508:Sarcolemma / Q000648:ultrastructure*; D012519:Sarcoplasmic Reticulum