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<br />TRANS, AM, MICROSC, SOC,
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<br />long (0,8-1.1 /-Lm) and thin (87-113 nm) (Fig, 6). A single electron-dense base
<br />plate is evident near the center of these microtriches; the shaft is long and
<br />spine-like in nature.
<br />The distal cytoplasmic layer is located between the surface plasma mem-
<br />brane and the basement membrane and is rich in membrane-bound vesicles
<br />(Figs. 6, 7), Small mitochondria (0.24-0.38 /-Lm) are numerous in the proximal
<br />one-third of the syncytial layer and cytoplasmic bridges connect this layer to
<br />the perikarya (Fig. 7).
<br />Microtriches on mature and gravid segments measured 0,12-0.16 /-Lm wide
<br />by 0,5-0.8 /-Lm long. They possess a clearly distinguishable base and shaft,
<br />and a prominent base plate (Fig. 7). The plate is located near the center of
<br />the microthrix and is comprised of a single, straight, electron-dense layer in
<br />contact with the plasma membrane.
<br />Sensory cilia were observed along the tegumental surface of the strobila
<br />(Figs, 7,8). The cilium emerges through a dendritic bulb and protrudes through
<br />the tegument. The cilia of these structures never protrudes higher than the
<br />surrounding microtriches, which probably accounts for their not being ob-
<br />served by SEM. The bulb of the sensilla is connected to the distal cytoplasm
<br />by septate desmosomes. Directly below the desmosomes is a single electron-
<br />dense collar. Most of the bulb is filled with oval, membrane-bound, electron-
<br />lucent vesicles. The cilia extend 1.1-1.2 /-Lm from the basal plate; a rootlet
<br />system was not observed (Fig, 8).
<br />Muscle bundles were observed within the perinuclear region of the cestode
<br />(Figs. 6, 7), These muscles are composed of myofibrils, with the thick fila-
<br />ments (myosin) measuring 20.1-25,3 nm in diameter and the thin filaments
<br />(actin) measuring 4.4-4.6 nm in diameter. The cytons contain large mito-
<br />chondria (0.98-1.21 /-Lm), glycogen granules (Fig. 9), actively secreting Golgi
<br />bodies (Fig, 10), rough endoplasmic reticulum, and large nuclei (Fig. 11).
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<br />FIGS, 1-5, Bothriocephalus acheilognathi; SEM, Fig, 1. Scolex showing pear-shaped both-
<br />rium, Fig, 2, Bilobed apical disc on the scolex, Fig, 3, Scolex tegument showing microtriches
<br />(MT) and tumuli (T), Fig, 4, Tegument within a bothrium showing slender microtriches (MT)
<br />and small tumuli (T), Fig, 5, Immature proglottid showing microtriches (MT) and tumuli (T),
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<br />FIGS, 6, 7, Bothriocephalus acheilognathi; TEM, Fig, 6, Scolex tegument showing a tumulus
<br />(T), microtriches (MT), distal cytoplasm (DC), dense-staining inclusions (1), basal lamina (BL),
<br />and muscles (MU), Inset shows detail of a scolex microthrix including the shaft (S), base (B),
<br />and base plate (BP), Fig, 7, Tegument of a mature segment showing a sensory structure (SS),
<br />microtriches (MT), distal cytoplasm (DC), vesicles (V), mitochondria (M), basal lamina (BL),
<br />cytoplasmic bridge (CB), and muscle (MU), Inset shows detail of a strobilar microthrix including
<br />the shaft (S), base (B), and base plate (BP),
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<br />FIGS, 8-11. Bothriocephalus acheilognathi; TEM, Fig, 8, Sensilla within the tegument of a
<br />mature segment shOWing a single electron-dense collar (C), septate desmosomes (SD), and ves-
<br />icles (V) within the dendritic bulb, FIg, 9, Perinuclear cytoplasm showing large mitochondria
<br />(M) and glycogen granules (GG), Fig, 10, Golgi body within the perinuclear cytoplasm, Fig, 11.
<br />A large nucleus (N) and rough endoplasmic reticulum (RER) within the perinuclear cytoplasm,
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