Fine Structure of the Cuticle of Female Onchocerca volvulus

Deas, Jane E.; Aguilar, Francisco J.; Miller, Joseph H.

doi:10.2307/3278537

Cited by 14 publications

(3 citation statements)

References 8 publications

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“…In contrast to the well-developed epicuticle of the male O. volvulus, that of the O. ochengi male is extremely thin. The O. volvulus female develops large protuberances from the epicuticle to the host tissue (Deas et al 1974;Franz 1988). As the growing female elongates, one can assume that the epicuticle is continuously renewed (Franz 1988).…”

Section: Discussionmentioning

confidence: 99%

Electron microscope observations on Onchocerca ochengi and O. fasciata (Nematoda: Filarioidea)

Determann

Mehlhorn

Ghaffar

1997

Parasitology Research

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The fine structure of the females and males of Onchocerca ochengi (parasitizing zebu and cattle) and of the females of O. fasciata from camels were described and compared to other filariae of the genus Onchocerca. It was shown that O. ochengi resembles O. volvulus of humans in its degree of development, while being more primitive than O. gibsoni. Besides other similarities O. ochengi attracts inflammatory cells in the way of O. volvulus and these could be a model for chemotherapeutic trials.

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Section: Discussionmentioning

confidence: 99%

Electron microscope observations on Onchocerca ochengi and O. fasciata (Nematoda: Filarioidea)

Determann

Mehlhorn

Ghaffar

1997

Parasitology Research

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“…The cuticle of O. volvulus and some Onchocerca spp. parasitising cattle exhibits a`honeycomb ' surface that greatly increases the surface area for solute absorption (Deas et al, 1974;Franz and Bu È ttner, 1983a;Franz et al, 1987) and, presumably, drug perm eation. This irregular, folded cuticle was seen in O. ochengi in the present study.…”

Section: Discussionmentioning

confidence: 99%

“…A similar`coat' to that seen surrounding female worms in the present study is present in the mid-body region of female O. volvulus (Franz, 1980) and has recently been described in another electronmicroscopic study of O. ochengi (Determ ann et al, 1997). It is not clear if this covering is formed by host material or is secreted by the worm, but the extension of lamellae into the coat provides a much larger surface area, and cellular debris in the area of the cuticular folds of O. volvulus may indicate some metabolic activity at this site (Deas et al, 1974).…”

Section: Discussionmentioning

confidence: 99%

In vitro uptake of ivermectin by adult male Onchocerca ochengi

Cross

Renz²,

Trees³

1998

Annals of Tropical Medicine And Parasitology

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Ivermectin is not lethal to the adult worms of Onchocerca volvulus or to those of O. ochengi, a cattle parasite closely related to O. volvulus. Although ivermectin penetrates the nodules in which the adults of these nematodes live, it is not known what levels of the drug enter the worms. Adult male O. ochengi were incubated in [3H]ivermectin in a saturated solution of unlabelled ivermectin (11.44 microM), to measure uptake by the oral and transcuticular routes, and in [3H]inulin, to ascertain if oral ingestion occurs in vitro. Uptake of [3H]ivermectin was high [1040 disintegrations/min (d.p.m.) at 3 h, representing a mean total of 86 pmoles ivermectin/worm] and occurred predominantly by the transcuticular route. Viability of worms was not reduced by this exposure, and uptake continued for up to 12 h. Only low levels of [3H]inulin (four d.p.m.) were detected in worms, indicating that the gut is probably not functional in vitro. Scanning and transmission electron microscopy revealed that the epicuticle of both sexes had an irregular surface which was pitted with a honeycomb structure in males, and rough and abundantly folded in females. These structures greatly increased the absorptive surface of the worms. In conclusion, ivermectin is able to enter adult O. ochengi males at concentrations sufficient to kill non-filarial nematodes.

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Electron-microscopic observations on the female worms of six Onchocerca species from cattle and red deer

1987

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The midbody regions of female worms of six Onchocerca species (O. flexuosa, O. tarsicola, O. lienalis, O. gutturosa, O. armillata, O. gibsoni) were studied by transmission electron microscopy. The cuticular layering was rather similar in all species with the ridges built up by the cortical layers and the inner cuticular striations by the median or basal layers. Differences in the epicuticular morphology were considerable. O. flexuosa and O. lienalis had a thin epicuticle without protuberances, the epicuticle of O. armillata carried small knobs, and O. tarsicola, O. gutturosa, and O. gibsoni had a thick trilaminar epicuticle with long protuberances. Extreme hypertrophy of hypodermis and reductions of somatic musculature were observed in O. flexuosa and O. gibsoni. Less extended thickenings of the hypodermis were observed in the other species. No degenerative alterations were found in the muscle cells of O. gutturosa and O. lienalis. The intestinal lumen of most of the species was in a central position, but in O. tarsicola and O. gibsoni the lumen was reduced to small clefts between the intestinal cells. In these species, numerous electron-dense, concentric granules were observed in the cytoplasm of the intestinal cells. The proportions of the various organs differed considerably from species to species, e.g., the uteri contained the embryos filed one behind the other in O. tarsicola, whereas 50 or more embryos were found beside one another in cross-sections of the uterus of O. gibsoni. The comparative study showed that O. gibsoni and O. volvulus have many derived morphological characteristics in common and that in the other species more primitive stages of development of these morphological marks can be observed.

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Fine Structure of the Cuticle of Female Onchocerca volvulus

Cited by 14 publications

References 8 publications

Electron microscope observations on Onchocerca ochengi and O. fasciata (Nematoda: Filarioidea)

Electron microscope observations on Onchocerca ochengi and O. fasciata (Nematoda: Filarioidea)

In vitro uptake of ivermectin by adult male Onchocerca ochengi

Electron-microscopic observations on the female worms of six Onchocerca species from cattle and red deer

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