Studi sulla muscolatura elicoidale e paramiosinica. Nota IV. La muscolatura longitudinale e circolare della parete corporea degli Anellidi Tubificidi
This paper deals with the body wall helical muscles of Tubificidae (Annelida, Oligochaeta). The majority of the longitudinal muscles are ribbonlike; their primary myofilaments are long and 300 Å thick; the secondary-primary filament ratio is about 7-8. Another kind of longitudinal muscle can be seen close to the basament membrane: they show a triangle-like section, and are easily recognizable because of the diameter of primary myofilaments (up to 600 Å), while the secondary-primary filament ratio...