[Immunocytochemical studies on the appearance and distribution of desmin during myogenesis in the embryos of Cynops orientalis]

Abstract

Indirect immunofluorescence was used to study the temporal appearance and spatial distribution of desmin during the myogenesis of the embryos of Cynops orientalis. Desmin is undetectable until stage 25. In stage 25 embryo, it can be seen that desmin is restrictively distributed at both ends of columnar cells, near the boundary between two somites and intense in the cells near by the notochord. From stage 26 to stage 30, the amount of desmin is increased and its distribution pattern shows little change (Plate I, Figs. 1-2). At stage 32 desmin can be detected in the cells more distal to the notochord and forms filaments on the inside of the cell membrane parallel to the long axis of the cell (Plate I, Fig. 3 and 5). Desmin filaments extend gradually from the both ends toward the mid-part of the cell (Plate I, Fig. 6 and Plate II, Figs. 7, 11-13). At about stage 40 the whole cell is filled with desmin filaments and the attachment of desmin to Z line can occasionally be detected (Plate II, Fig. 8). Desmin attached to Z line is increased at stage 41 (Plate II, Fig. 9) and at stage 43 most of the desmin is found attached to Z line (Plate II, Fig.10). According to EM observation, Z line structure can be seen in stage 33 embryo (Wang[18]), but desmin remains in the filament form till stage 40. The transference of desmin distribution pattern from filament to Z line occurs somewhat later than the appearance of scattered sarcomeres. The possibility that notochord may be the main factor which influences the spatial localization of desmin was analyzed. The relationship between the transference of desmin from filament to Z line attached form and the quantitative changes of both desmin and sarcomere was discussed.