title: Ultrastructural peculiarities of the inner portion of the circular layer of colon. I. Research in the human.
abstract: The inner part of the circular layer of the human colon is made up of a special muscle layer, three to eight row thick. Wide areas of connective tissue are found inside this inner circular layer and between it and the outer part of the circular layer. The muscle cells of this innermost layer have several special features: numerous glycogen particles and caveolae, well-developed sarcoplasmic reticulum, and wide contact areas with each other. At the border zone with the tela submucosa, there is a fibrous lamella rich in collagen and elastic fibers, lined by an incomplete layer of circularly orientated fibroblast-like cells. A nerve plexus, rich in varicosities, is located between the two circular layers, and nerve fibers are sparsely located inside the fibrous lamella. Interstitial cells of Cajal were not recognized.
mesh_terms: D000328:Adult; D002462:Cell Membrane / Q000648:ultrastructure; D003094:Collagen / Q000502:physiology; D003106:Colon / Q000648:ultrastructure*; D004547:Elastic Tissue / Q000648:ultrastructure; D005260:Female; D006801:Humans; D008297:Male; D008854:Microscopy, Electron; D008875:Middle Aged; D009132:Muscles / Q000166:cytology / Q000648:ultrastructure*; D012519:Sarcoplasmic Reticulum / Q000648:ultrastructure
chemical_list: D003094:Collagen