has part has part has_part composed primarily of smooth muscle cell elastic fiber smooth muscle tissue Glatte:Muskelzellen.jpg MESH:D009130 NCIT:C12437 GO uses visceral and smooth interchangeably. However visceral can also be used in the sense of the viscera. Many fly annotations to smooth muscle terms. If we want to be inclusive of insects have to have a general definition of tissue that includes cells. AAO:0010244 TAO:0005274 visceral muscle tissue EHDAA2:0003141 MIAA:0000303 galen:SmoothMuscle FMA:14070 visceral muscle MA:0000166 GAID:167 OpenCyc:Mx4rvvSS3pwpEbGdrcN5Y29ycA Involuntary muscle tissue consisting of uninucleate spindle-shaped fibers.[AAO] ZFA:0005274 WBbt:0005781 A non-striated muscle that is composed of spindle-shaped cells. Smooth muscle usually is organized into sheets that line cavitated organs.[TAO] EV:0100378 uberon EFO:0000889 EMAPA:32717 galen:SmoothMuscleTissue CALOHA:TS-0943 AEO:0000141 MAT:0000303 involuntary muscle textus muscularis nonstriatus Muscle tissue which is unstriated, composed primarily of smooth muscle fibers surrounded by a reticulum of collagen and elastic fibers. Smooth muscle differs from striated muscle in the much higher actin/myosin ratio, the absence of conspicuous sarcomeres and the ability to contract to a much smaller fraction of its resting length[GO]. textus muscularis levis; textus muscularis nonstriatus FBbt:00003525 BTO:0001260 UMLS:C1267092 (...) the first bilateral animals possessed only smooth muscles with the molecular repertoire necessary to build a striated muscle. (...) it is more parsimonious to regard striated muscle cells as a sister cell type to the smooth muscle cells. In this scenario, striated and smooth muscles would have arisen in the stem lineage that led to the Nephrozoa (i.e. all Bilateria exclusive the acoelomorphs) (Hejnol et al., 2009), from an 'acoel-like' smooth muscle, by segregation and divergence of functions and through differential recruitment of additional genes[well established][VHOG] VHOG:0001246 UBERON:0001135 XAO:0000175 smooth muscle non-striated muscle Wikipedia:Smooth_muscle_tissue muscle tissue