COMPARATIVE ULTRASTRUCTURE OF THE CYTOPLASM IN SPECIES OF THE GENUS TRACHELORAPHIS (CILIOPHORA, KARYORELICTIDA) .2. ENDOPLASMIC ORGANELLES AND GENESIS OF RHABDOCYSTS

The endoplasm of five Tracheloraphis species, Tr. dogieli, Tr. phoenic opterus, Tr. totevi, Tr. crassus and Tr. caudatus, has been investigat ed. The endoplasm of all species is permeated with an extensive genera l lacunary system, the ground cytoplasm being reduced to a network of interconnected cytoplasmic islets which contain the cell organelles. T he mitochondria have tubular cristae and variably dense matrix. They a ccumulate beneath the myonemes and under the non-ciliated stripe. Some mitochondria of Tr. dogieli show reduced cristae. The Golgi bodies ar e numerous near the ciliated body surface and consist of up to ten fla ttened cisternae. Some species (Tr. phoenicopterus, Tr. crassus) conta in refractile electron-lucent inclusions lying inside the endoplasmic lacunae, others (Tr. dogieli) contain large protein globules, devoid o f own membrane, lying in the ground cytoplasm. The lipid droplets also lie in the ground cytoplasm and are not surrounded with an own membra ne. The rhabdocysts are formed within membrane vesicles inside endopla smic islets which are rich in ribosomes. In the vesicles, the head and the shaft of the extrusomes are progressively formed. At last, rhabdo dysts migrate to the periphery of the cell and become docked in the in terkinetal papillae accompanying ventral kineties.