Morphological Features and Temporary Characteristics of the Process of Muscle Tissue Regeneration in Planaria Polycelis tenuis (Platyhelminthes)

A body musculature of the planarian Polycelis tenuis (Turbellaria, Platyhelminthes) has been investigated by fluorescence microscopy using histochemical staining of whole preparations with fluorescently-labeled phalloidin, which stains muscle cells due to irreversible binding to actin filaments. The results showed that the musculature of the body wall contains circular, diagonal and longitudinal muscle fibers. The circular fibers are the thinnest ones and densely located within the outer layer of the muscle. The longitudinal fibers are thick, gathered into bundles. Individual diagonal muscle fibers are located at a significant distance, in two directions and at an angle to each other. In the work, the process of muscle tissue regeneration in P. tenuis is considered after removal of the planarian’s head. The current study investigates tissue regeneration on days 3, 5, 7, 10 and 13 following tissue amputation. The microscopy images provided valuable information about the main stages of muscle tissue regeneration and their characteristic features. It has been shown that the muscular system in P. tenuis has awesome regenerative abilities and tissue is regenerated within 10–13 days.