. The Biological bulletin. Biology; Zoology; Biology; Marine Biology. 126 M. ENZIEN ET AL. Figure 14. Cortical tubules (arrow) presumably originating from rtm of Figure 16. closely associated with the anteriorly positioned nu- cleus (N) of mastigote. Bracket indicates "rostral ridge" (IT). TEM. Bar scale = f/m. correspond to those observed with light microscopy are depicted (Figs. 8A; 9A). The "buds," at least in Figure 12, are continuous with the cell cytoplasm and probably not an artifact resulting from overlapping amoebae. The "buds" lack both mitochondria
. The Biological bulletin. Biology; Zoology; Biology; Marine Biology. 126 M. ENZIEN ET AL. Figure 14. Cortical tubules (arrow) presumably originating from rtm of Figure 16. closely associated with the anteriorly positioned nu- cleus (N) of mastigote. Bracket indicates "rostral ridge" (IT). TEM. Bar scale = f/m. correspond to those observed with light microscopy are depicted (Figs. 8A; 9A). The "buds," at least in Figure 12, are continuous with the cell cytoplasm and probably not an artifact resulting from overlapping amoebae. The "buds" lack both mitochondria and chromatin bodies in this particular micrograph, but this may simply be a function of orientation of this thin section. Because the details of mitotic division remain elusive, the case for multiple fission in this organism is incomplete and we still have no comprehensive view of how the luxuriant, rapid growth of this organism is achieved. The "buds" represent frequently observed oddities; they may or may not represent part of the amoeba reproduction process. If chromatin bodies originate from the nucleus, which is not yet clear, then budding could represent a means of their dispersion. Although mitosis has never been observed in ultra- structural studies of Paratetramitus jugoxus amoebae or mastigotes, some events associated with mitosis are evi- dent in thin sections. We have seen dumbbell-shaped chromatin bodies (Fig. 10A, D) and a single binuclear cell: a mastigote in which karyokinesis but not cytokine- sis apparently has occurred (Fig. 13). Mastigotes share many features with amoebae and cysts, including mitochondria surrounded by rough en- doplasmic reticulum (RER), large vacuoles, strands of rough endoplasmic reticulum, nuclei with a prominent nucleolus, and nuclear membrane surrounded by ribo- somes (Figs. 13, 14). However, the three forms do differ significantly. The nucleus, anteriorly located in masti- gotes and attached by rhizoplast microtubules to th
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