SYNOPSIS. Several fine‐structural changes were observed during formation of the so‐called pseudocysts of Trichomitus batrachorum grown in an agar‐free medium. Among these changes the most frequent were those of the undulating membrane complex. Internalization of the marginal lamella combined with disappearance of the fin‐like, membranous dorsal fold occurred with the highest frequency. In many organisms these alterations were accompanied by internalization of the recurrent flagellum, which, however, remained external in other, presumably earlier stages of pseudocyst formation. In some of the internalized and even still external recurrent flagella the microtubules were in various states of disassembly. The often distended flagellar membrane enclosed large accumulations of filaments 5 nm in diameter. Internalization of the anterior flagella also was noted. Changes similar to those characteristic of the recurrent flagella were not seen, however, among the microtubules of the anterior flagella or among those of the pelta or the axostyle.
SYNOPSIS. Tritrichomonas muris shares many fine‐structural details with the previously described members of the family Trichomonadidae, and especially with the organisms belonging to the subfamily Tritrichomonadinae. Among the features which T. muris has in common with all Trichomonadidae and in all probability with other Trichomonadida are the arrangement and structure of: the kinetosomes; many rootlet filaments, including the sigmoid filaments of kinetosome #2; the parabasal apparatus; and the pelta‐axostyle complex. The structures which T. muris ‐type flagellates share with other Tritrichomonadinae, and especially with Tritrichomonas augusta ‐type species (including T. foetus ), but not with Trichomonadinae that have been studied to date, are: the Type A costa; a comb‐like structure, which appears to have replaced the costal base of Trichomonadinae and of Hypotrichomonas ; the suprakinetosomal body, rudimentary in T. muris ; and the infrakinetosomal body. The undulating membrane, like that of T. augusta ‐type organisms, consists of a proximal and a distal part. The proximal part, which contains the proximal marginal lamella, is less developed in T. muris than in T. augusta ‐type flagellates, being represented by a relatively low ridge for the entire length of the organism. The distal part of the membrane in T. muris , on the other hand, is more highly developed; it is a heavy cord, with a distal marginal lamella which consists of a large triangular organelle having a highly ordered structure and 2 less well defined cords distal to this organelle. The tubules of the recurrent flagellum occupy the area distal to the cords. The sigmoid filaments of kinetosome #2, unlike those of other Trichomonadidae examined to date, extend posteriorly to the peltar‐axostylar junction; they seem to terminate within the cytoplasm near, but not connected to the axostyle. In addition to the Type A costa, there is a small rootlet filament, which appears to be homologous to the rudimentary costa noted in Hypotrichomonas. Some of the paraxostylar and paracostal granules consist of an outer, relatively dense layer and an inner “core” of moderate density; between the 2 there is a lucent ring. The discussion deals in some detail with the possible nature of the paraxostylar and paracostal granules in trichomonads. The taxonomic status of Tritrichomonas cricetus (Wantland) [ Tritrichomonas criceti (Wantland) emend. Levine] and Trichomonas criceti Ray & Sen Gupta is discussed in an appendix; it is concluded that both of these names are synonyms of T. muris (Grassi).
Evidence of human immunodeficiency virus (HIV) replication was sought in human placentas obtained at term from pregnancies complicated by maternal HIV infection. Placentas were obtained from the pregnancies of 19 HIV-seropositive women, 4 women who were seronegative, and 4 untested women with no risk factors for HIV infection. These placentas were each examined by immunoperoxidase immunocytochemistry using monoclonal anti-p24/55 antibodies. In addition, minced placental tissue from 11 of the seropositive pregnancies and the 3 seronegative pregnancies were co-cultivated with stimulated human peripheral blood mononuclear cells. The clinical status of the infants born to the HIV-seropositive women was assessed when the infants were 8 to 28 months of age. P24/55 antigen was detected in 5 of the 19 placentas of the HIV-seropositive pregnancies and in none of the 8 placentas of seronegative or low-risk pregnancies. This HIV core viral antigen was located exclusively in the cytoplasm of villous cells with morphological characteristics of macrophages. The HIV antigen-containing cells were very sparsely distributed. Staining of the trophoblast was not observed in any placental specimen. Human immunodeficiency virus was isolated in culture from 3 of the 11 placentas from seropositive pregnancies. Clinical follow-up has not revealed a relationship between infection of the infant and either p24/55 antigen identification or isolation of virus from the placenta. Virological and histological evidence of HIV replication is found in approximately one fourth of placentas obtained at term from pregnancies complicated by maternal HIV infection. Replicating virus appears localized to sparse macrophages located within the chorionic villi, but specifically not within the trophoblastic layer.(ABSTRACT TRUNCATED AT 250 WORDS)
Female golden hamsters, either in the last week of pregnancy or in the first weeks of nursing, excreted in their feces variable numbers of pseudocysts of Tritrichomonas muris. Pseudocysts examined by electron microscopy had internalization of the 3 anterior flagella and the undulating membrane with its recurrent flagellum. The undulating membrane and the associated marginal lamellae were characteristic of T. muris. Pseudocysts gradually become motile after 2 or more hours of incubation in medium. The "excysted" trophozoites were identified ultrastructurally as T. muris. Newborn hamsters were not infected with T. muris at 3 days of age, but by the 7th day essentially all were found to have infected ceca, concomitant with cecal enlargement and the appearance of adult-type feces.
Newborn hamsters inoculated intrahepatically were highly susceptible to infection by axenically cultured Entamoeba histolytica. Inoculations were performed through the abdominal wall, and lesions could be observed through the skin as early as 4 days after inoculation. The most virulent amebal strain, HM-1:IMSS, produced liver lesions in 19% of newborn animals inoculated with 20 amebae, and in about 90% receiving 2,000 amebae. Eleven other strains similarly tested either produced no lesions with 20,000 amebae or were of intermediate virulence. Two hamster strains did not show appreciable differences in susceptibility to the HM-1:IMSS amebal strain. Newborn hamsters were more susceptible to HM-1:IMSS amebae than animals which were 2, 4, or 7 days old at the time of inoculation. Three-week-old animals were resistant to doses below 20,000 virulent amebae.
The DNA of Leishmania enriettii can be separated by equilibrium sedimentation in cesium chloride into a major band of density 1.721 and a minor component of density 1.699. DNA from isolated kinetoplasts of this protozoan was identified as the less dense minor component.
SYNOPSIS. Electron‐microscopic observations of Spirostomum ambiguum have demonstrated additional details of superficial and deep tubular connections with peristomial and somatic kinetosomes. The superficial peristomial tubules appear to connect adjacent rows of kinetosomes. Anatomically, they course distally from the proximal kinetosomal plate. The deep tubules run proximally from the kinetosomal plate. Those in the somatic region appear to enter the endoplasm; those in the peristomial region leave the kinetosome as bundles of either 10 or 11 tubules which steadily converge to form 2 compact rows of 10 tubular bundles. These tubules connect to 2 of the 3 rows of 10 cilia each, the rows of 3 being separated by membranous folds protruding perpendicular to the peristomial groove. The rows of bundles converge further, enter the endoplasm and fan out again into tubular sheets, some of which appear to course in an antero‐posterior direction. Another set of tubules arises from each of the kinetosomes in the 3rd row of 10 kinetosomes and courses proximally at a different angle from those arising from the 2 other kinetosome rows. Terminations have not been observed for the deep somatic or peristomial tubules. Their possible role in producing the forceful longitudinal contraction of Spirostomum is discussed.
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