Susan Stamford

The penetration of the salivary glands of Rhodnius prolixus by Trypanosoma rangeli.

Ultrastructural studies of the mechanism of penetration of the salivary gland of the reduviid bugRhodnius prolixus byTrypanosoma rangeli showed that trypanosomes from the haemocoele penetrate the outer “membranes” of the gland flagellum foremost, disrupting the inner layers, to pass between the muscle cells to reach the gland cell basement membrane. This latter is also penetrated flagellum foremost, the parasite invaginating the gland cell plasmalemma beneath, to create a vacuole in which the trypanosome crosses the gland cells to reach the central lumen, often only losing its containing vacuole just before leaving the cell.The structure of the outer “membranes” surrounding the salivary gland appeared similar to, and often actually part of, the basement membrane of the gland cells. These outer “membranes” were found to enclose large numbers of multinuleate “giant form” trypanosomes, whose significance is as yet unknown, but could perhaps represent a stage in the life cycle of the parasite where genetic interchange could take place.

Congo/Crimean haemorrhagic fever virus from Iraq 1979: I. Morphology in BHK21 cells.

SummaryCongo-Crimean Haemorrhagic Fever virus, isolated from a patient in Iraq, was grown, after passage in suckling mouse brain, in BHK cells. The particles matured after 8–9 days in these cells by budding, usually singly, into cytoplasmic vacuoles throughout the host cells. The virions had an overall diameter of 115 to 125 nm, including rounded surface spikes 15 nm long and 10 nm wide. The viral cores, surrounded by a lipid unit membrane, contained discrete electron-dense elements. It is suggested that the spikes, dimpled at their outer end and possibly hollow throughout their length, passed out through “pores” in the unit membrane.

Interaction between Trypanosoma brucei and the ependymal cell of the choroid plexus

The fine structure of the normal choroid plexus of rats and mice and of those infected with Trypanosoma brucei was examined by transmission and scanning electron microscopy: extracellular trypomastigotes in the perivascular stroma predominate but the evidence presented suggests that they are derived both from stages in the blood and from others undergoing division within ependymal cells, a process which results in destruction of a large proportion of ependymal cells in the parts of choroid plexus affected. The choroid plexus maintains its integrity by regeneration of an outer layer of ependymal cells.

Evaluation of plaque size reduction as a method for the detection of Pichinde virus antibody.

SummaryThe reaction between Pichinde virus and homologous antisera has been studied using a plaque size reduction method. The incorporation of antiserum in the overlay of infected Vero cell monolayers revealed a pattern of virus-cell interactions which were manifested by both a significant reduction in the diameter of virus plaques, and regeneration of cells in the centre of each. Electron microscopy demonstrated that antibody molecules were bound to virus particles budding from the surface of infected cells resulting in the formation of extracellular virus-antibody complexes. These aggregates were subsequently detected in vacuoles of freshly-infected cells. In the absence of virus neutralization, reaction of Pichinde virus with homologous antiserum leads to the formation of infectious aggregates which due to their larger size restrict the rate of plaque development.

A Simple Vacuum Pipette For Processing Groups Of Specimens For Electron Microscopy

A standard sink filter pump attached to a special glass adaptor, holding pipettes, enables groups of specimens to be fixed and dehydrated for electron microscopy with speed and safety.

A brief note on an arrangement of sub-pellicular tubules in trypanosomes

Early work using electron microscopy in the study of trypanosomes revealed fibrillar structures beneath the pellicle (Kleinschmidt 1951). As better techniques of fixation (Sabatini et al. 1963) and embedding (Glauert et al. 1956) were introduced, it was found that these structures were tubules and that they decreased in number at each end of the trypanosome (Figs. 1 and 2) down to as few as five or six, while over 100 could be counted in central regions (Fig. 3). These tubules spiralled around the organism, making it difficult to obtain easily countable transverse sections of them in serial sections, though the decrease in numbers towards the ends of the organism was always obvious, Meyer and De Sousa (1976) demonstrated a clear spacing pattern in Trypanosoma cruzi which was further analysed by Dvorak (1979), but a minor problem has existed as to how the numbers of these tubules were reduced; did adjacent tubules fuse to reduce the total number, or did some tubules simply end and their neighbours close ranks to maintain to regular spacing pattern s e e n throughout the length of this trypanosome? The sections shown in the figures are of metacyclic forms of Trypanosoma brucei brucei stock, LUMP 1144 (one mouse passage from TREU 667) found in the salivary glands of Glossina morsitans morsitans (from the Tsetse Research Laboratory, Bristol, England). The glands were fixed by the special technique of Ledingham and Simpson (1972), using p-phenylene-diamine to enhance the contrast in the salivary glands. Although this fixation technique does not provide for as good preparations as the glutaraldehyde-osmium tetroxide method employed for blood stream and midgut forms of salivarian trypanosomes (eg, Evans et al. 1979), it yields quite satisfactory preparations of the salivary gland forms, which are notoriously difficult to fix. Figure 4 shows the ending of two tubules beneath the pellicle of a trypomastigote in the lumen of the salivary gland, where no fusion has taken place, but where the adjacent tubules have closed up to maintain the regular spacing intervals. Presumably this is the mechanism used in trypanosomes to reduce the number of subpellicular tubules progressively towards each end of the body of the organism. This information came from a section cut at just the right