Fine structure of the pharyngeal bulb in Trilobodrilus and its phylogenetic significance within archiannelida.
Transmission electron microscopical studies of the pharyngeal bulb in the archiannelid Trilobodrilus sp. proved the presence of two opposing myofilament systems in the plate muscle cells forming this bulb. These muscles are obliquely striated. The significance as well as the origin of this specialized plate-muscle cells in the pharyngeal bulb of archiannelids is discussed in the light of their controversial phylogenetic and systematic position. In addition a hypothesis is suggested to explain the origin of the special arrangement of two opposing systems of myofilaments in one single muscle cell.
D000818:Animals; D000845:Annelida / Q000145:classification / Q000648:ultrastructure*; D002467:Cell Nucleus / Q000648:ultrastructure; D008566:Membranes / Q000648:ultrastructure; D008931:Mitochondria, Muscle / Q000648:ultrastructure; D008961:Models, Structural; D009119:Muscle Contraction; D009132:Muscles; D009210:Myofibrils / Q000648:ultrastructure; D010614:Pharynx / Q000648:ultrastructure; D010802:Phylogeny; D012519:Sarcoplasmic Reticulum / Q000648:ultrastructure