The ultrastructural research of two childhood type of polymyositis was reported. Under the electron microscope and phase contrast microscope, the affected muscle cells are characterised by degencration. The z lines may become distorted, thickened and various other form. These alterations may be correlative with A and I band The mu-scle cells show abnormal mitochondria, T-tubules decreased apparantly, especially con-tracture of the thin myofilaments and its selective lossOwing to these phenomena is nonpscific alttrlation of skeletal muscle. Therefore, this report maybe of some representative meaning for other skeleletal myopathy analyses of pathologic ultrastrctural morphology. Beside, pathogensis was dicussed.

A method by using ?-BT-HRP conjugate to localize N-acetylcholinc receptor of neuromuscular junction was described.Thin strips of fresh muscle were incubated with ?-BT-HRP conjugate at a concentration of 1?10-7 M in Tyroid's solution and then reacted with Karnovsky's DAB medium.There were obviously brownish red positive deposits to constitute various vesicular forms seen under a light microscope. Under an electron microscope we can see positive deposits that were localized both on the presynaptic and postsynaptic membra-nes. The binding activity and reliability of a-BT-HRP were discussed.

We report in detail ultrastructural changes and freezing damage mechanism about heart muscle and some organelles after rapid freezing. The ventricles of rat heart were cut pieces about 100-150/?m by microsiicer. The pieces were quickly injected liquid cryogen Freon 22 by Reichert-Jung spring-assistant mechanism (KF-80). The specimens frozen were rapidly transferred into substitution medium aceton and kept at -80℃(28h), then -60℃ (48h),-20℃(12h)and 4℃ (1 h). The structures of specimens frozen were well and there were no ice crystals in the area of the tissue frozen surface to 20?m depth. However, there were freezing damages in mitochondrial crista, intercellular substance and muscular fibre in the tissue surface to 30?m depth. The structure of tissue was destroyed by ice crystal over 50?m depth in the tissue. The results suggest that intercellular substance and mitochondrial crista are the most sensitive to ice crystal damage after rapid freezing of heart tissue, then the less sensitive are muscular fibre and nucleus. The unit membrane is not easy to be damaged by ice crystal.