Trichinella spiralis: induction of the basophilic transformation of muscle cells by synchronous newborn larvae. II. Electron microscopy study.

The present ultrastructure observations apply to the same experimental groups that were investigated in the first part of the study. The results of electron microscopy investigations correspond to those obtained using light microscopy methods. The ultrastructure data demonstrated that 1-h-old sNBL (group I) penetrated into the sarcoplasm of the muscle cells and transformed it basophilically, finally creating the "nurse cell-muscle larva complex." These larvae also caused transformation of the same muscle cells without being present in the sarcoplasm. The larvae of group II (9-h-old sNBL) preserved transformation potential as well, but it was less intensive. Not all NBL settled in the muscle cells; some of them remained in the intercellular spaces. Group II larvae present in the muscle cells underwent early degeneration and necrosis more often than did group I larvae; the inflammatory cell reactions in the vicinity of the larvae were more intensive. The basophilic transformation of muscle cells that did not contain larvae in their sarcoplasm was not intensive and often stopped at the level of cell nuclei. The larvae of group III (6-day-old sNBL) neither settled in the muscle cells nor transformed the cell sarcoplasm.