The fenestrated collar of mammalian cardiac sarcoplasmic reticulum: a freeze-fracture study.
Freeze-fracture studies of papillary muscles from cat, rabbit and dog reveal the presence of a fenestrated collar of the sarcoplasmic reticulum (SR) in the region of the M band. This membrane specialization is structurally similar to that observed previously in skeletal muscle. This report includes mammalian cardiac muscle on the list of those muscles containing this SR membrane structure.
D000818:Animals; D002415:Cats; D004285:Dogs; D005614:Freeze Fracturing; D008854:Microscopy, Electron; D010210:Papillary Muscles / Q000648:ultrastructure*; D011817:Rabbits; D012519:Sarcoplasmic Reticulum / Q000648:ultrastructure*