Elektronenmikroskopische Untersuchungen an den Entwicklungsstadien des Trophozoiten von Didymophyes gigantea (Sporozoa, Gregarinida)

Summary

The fine structure of the deutomerite of D. gigantea was investigated. The development of the nuclear apparatus, the nuclear division, and the Golgi apparatus are emphasized. In its earliest stage, the young trophozoite has only one nucleus displaying a rather dense but heterogeneous karyosome. The adult trophozoite has nuclei with a homogeneous nucleolus. During the evolution of the trophozoite — even before the association of two individuals to a syzygy — appear very rapid successive nuclear divisions (Fig. 3), so that adult syzygies may display several hundred nuclei in each individual (Fig. 5). The spherical structure (Fig. 1) considered by Legar (1892) as nucleus has been revealed to be a large vaculole with fine granular or fibrillar material (Fig. 6). Rather often nuclei are surrounded by cyternae of endoplasmic reticulum (Fig. 7) or display large cytoplasmic invaginations (Fig. 8). The intranuclear spindle-apparatus is characterized by a polar centrocone-like structure (Figs. 9–12). Intranclear microtubuli can often be observed (Figs. 9, 10, 15, 18). The nucleolus is separating just before the definite nuclear division (Figs. 13–15). New nuclear division can start even if the preceding one is not yet finished (Fig. 18). The Golgi apparatus is rather complex. There can be observed dictyosomes in relation with the nuclear envelope, and endoplasmic reticulum serves in the case as intermediate organite (Figs. 18–27, 31). Besides these dictyosomes exist other dictyosomes free of endoplasmic reticulum and containing dense material in their vesicles (Figs. 29, 30). These two types of dictyosomes are probably different evolution stages of one whole Golgi apparatus.