STUDIES ON THE STRUCTURE OF THE FEMALE REPRODUCTIVE SYSTEM AND EGG-SHELL FORMATION IN ASPICULURIS TETRAPTERA SCHULZ, (NEMATODA: OXYUROIDEA).
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The life-cycle of Syphacia muris is described in primary infections of Wistar rats. The life-cycle of S. muris is completed within seven days and no moults were discovered inside the egg. Instead each of two moults were observed outside the egg up to 24 and 40 hours after infection, and TEM studies suggest a third moult occurs up to 64 hours. The development and maturation of the larval stages are described for the first time using both light and electron microscopy. Differences in the size and growth of female S. muris compared with previously published figures could be due to differences in the strains of rats used.
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The ovary of Aspiculuris tetraptera has a prominent terminal cap cell. This is considered to be part of the ovarian epithelium. Oogonia detach from the short rachis and increase in size from 6 to 60 microns; accumulating hyaline granules, shell granules and glycogen. The hyaline granules persist in the eff cytoplasm after shell formation has been completed and are considered to be lipoprotein yolk. The shell granules contribute to the non-chitin fraction of the chitinous layer. A classification of the cytoplasmic inclusions of the nematode oocyte is proposed. Upon fertilization a vitelline membrane is formed which constitutes the vitelline layer of the egg-shell. The chitinous layer is secreted in the perivitelline space, between the vitelline layer and the egg oolemma. Upon completion of chitinous layer synthesis, the egg cytoplasm contracts away from its inner surface. The material of the lipid layer is secreted at the surface of the egg cytoplasm and adheres to the inner surface of the chitinous layer. During secretion of the chitinous and lipid layers by the egg cytoplasm, the uterine cells secrete the unit membrane-like external uterine layer and the crystalline internal uterine layer. A complex system of interconnecting spaces develops in the internal uterine layer. This system is open to the exterior via breaks in the external uterine layer. There is no direct involvement of the uterine cells in the formation of this structure.
The egg of Aspiculuris tetraptera is an ellipsoid measuring 93 x 40 microns. The shell consists of 5 layers: the external uterine layer, internal uterine layer, vitelline layer, chitinous layer and the lipid layer. This nomenclature is based upon the formation and histochemistry of the shell layers. The internal uterine layer contains a system of interconnecting spaces, partly filled by uterine secretion, which open to the exterior of the egg via breaks in the external uterine layer. The surface of the egg is covered by a system of interconnecting grooves. Freeze-etching reveals that the internal uterine layer is open to the exterior via pores, which open into the grooves. Rod-shaped particles are also revealed in the external uterine layer. The operculum of the egg consists of a modification of the uterine and chitinous layers of the shell.
Gametogenesis is described in Tachygonetria conica, T. dentata, T. macrolaimus, T. numidica, T. longicollis longicollis, T. l. pusilla, T. l. setosa, Mehdiella uncinata and M. microstoma, parasites of Testudo graeca from Tunisia. All species reproduced by haplodiploidy (males developed from unfertilized eggs and were haploid and females developed from fertilized eggs and were diploid). Metaphase of oogonial divisions contained ten rod-shaped chromosomes and meiosis in females resulted in two polar bodies and an egg pronucleus. Embryos in eggs in utero contained either five or ten chromosomes depending presumably on whether or not they developed from fertilized ova. Metaphase of spermatogonial divisions contained five rod-shaped chromosomes but divisions just anterior to the seminal vesicle contained five short round chromosomes similar to meiotic chromosomes but consisting of only two chromatids. Males of haplodiploid species have no homologous chromosomes and it is suggested that meiosis during spermatogenesis, rather than being replaced by mitosis as previously suggested (Adamson, 1981), simply begins at the second meiotic division.
Forty specimens of Haemulon sciurus were examined for endoparasites and this paper refers to the recovered Nematodes and Acanthocephalans. Aspiculuris tetraptera is for the first time referred in fish and Dollfusentis chandleri is recorded in Brazil and in a new host.
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Syphacia muris worm burdens were evaluated in the rat Rattus norvegicus of the strains Wistar (outbred), Low/M and AM/2/Torr (inbred), maintained conventionally in institutional animal houses in Brazil. Morphometrics and illustration data for S. muris recovered from Brazilian laboratory rats are provided for the first time since its proposition in 1935.
We describe the first account of the nematode Gyrinicola batrachiensis in the gastrointestinal tracts of tadpoles of Bufo terrestris, Gastrophryne carolinensis, Hyla femoralis, H. squirella, Rana heckscheri, and R. utricularia. Infection by G. batrachiensis was also noted in tadpoles of R. catesbeiana and R. clamitans, species previously described as harboring these nematodes. These observations represent a major expansion of the known geographical range of G. batrachiensis to include the southeastern United States. In our study, female G. batrachiensis nematodes in ranid host species were didelphic, but females in B. terrestris tadpoles were monodelphic. Furthermore, only female nematodes were found in the latter host species. Such variations in nematode uterine morphology and sex ratios among these tadpole host species are in accordance with the apomictic and haplodiploid reproductive strategies previously reported for G. batrachiensis. These observations also support a generalized pattern relating G. batrachiensis reproductive modes and the life cycles of their tadpole hosts.
Parapharyngodon kenyaensis n. sp. and Thelandros samburuensis n. sp. (Nematoda: Pharyngodonidae) from the large intestine of the agamid lizard (Agama caudospina) are described and illustrated. Parapharyngodon kenyaensis n. sp. is the 41st species assigned to the genus, and it differs from other species in that genus by possessing 3 pairs of caudal papillae, cloacal lip adornment, and spicules of 112-120 microm in length. Thelandros samburuensis n. sp. is the 31st species assigned to the genus, and it differs from other species in that genus by possessing swollen posterior annulations, 6 caudal papillae, a smooth anterior cloacal lip, and spicules of 43-52 microm in length. In addition to the 2 new nematode species, Abbreviata ortleppi (Nematoda: Physalopteridae) and Strongyluris ornata (Nematoda: Heterakidae) were found.
Okinawandros goldbergi n. gen., n. sp. and Ataronema sekii n. gen., n. sp. (Nematoda: Pharyngodonidae) are described from rhacophorid frogs of the Ryukyu Archipelago, Japan. Okinawandros n. gen. resembles Batracholandros Freitas et Ibañez, 1965 and Synodontisia Petter, Vassiliades et Troncy, 1972 but is readily distinguished from the former in lacking laterally situated genital papillae and by having anteriorly directed vagina and from the latter by having operculated eggs and lacking a spicule. Ataronema n. gen. most closely resembles Parathelandros Baylis, 1930 but is readily distinguished because the posterior pair of caudal papillae is not rosette shaped and the eggs are not operculated. Morphological notes of Pharyngodon polypedatis Yamaguti, 1941 are included.