title: Adaptive changes in muscle fibers infected with Trichinella spiralis.
abstract: Ultrastructural changes which occurred in infected skeletal muscle fibers after infection with larvae of Trichinella spiralis were followed on a daily basis utilizing synchronous infections. No changes were observed in muscle fiber architecture during the first 2 days of intracellular infection. However, on Day 3, a space containing various sarcoplasmic elements developed between the plasma membrane and myofilaments. Widening near the regions of triads was also observed at this time. On Day 4 the space at the outer edge had increased, as did the ones at the triads. In addition, the myofilaments throughout the infected fiber were in a state of partial disarray. Finally, the nuclei were enlarged and had migrated to the central portion of the infected cytoplasm. On Day 5 day, sarcomeres were highly disorganized, and an increase in sarcoplasmic reticulum (SR) was noted. By Day 8, only the extreme periphery of the infected fiber contained Z bands with actin filaments attached. Proliferation of the t tuble system was also evident. At Day 10, myofilaments were completely replaced with SR. Further, the plasma membrane became hyperinvoluted and was associated with a 36-fold increase in the thickness of the glycocalyx. No further enlargement of nuclei occurred after Day 10. Finally, a host-derived double membrane completely surrounded the larva.
mesh_terms: D000818:Animals; D002462:Cell Membrane / Q000469:parasitology / Q000648:ultrastructure; D002467:Cell Nucleus / Q000469:parasitology / Q000648:ultrastructure; D004721:Endoplasmic Reticulum / Q000469:parasitology / Q000648:ultrastructure; D006023:Glycoproteins; D051379:Mice; D008815:Mice, Inbred Strains; D008854:Microscopy, Electron; D008931:Mitochondria, Muscle / Q000469:parasitology / Q000648:ultrastructure; D009119:Muscle Contraction; D009210:Myofibrils / Q000469:parasitology / Q000648:ultrastructure*; D011132:Polyribosomes / Q000469:parasitology / Q000648:ultrastructure; D011134:Polysaccharides; D051381:Rats; D012519:Sarcoplasmic Reticulum / Q000469:parasitology / Q000648:ultrastructure; D014235:Trichinellosis / Q000473:pathology*
chemical_list: D006023:Glycoproteins; D011134:Polysaccharides