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Journal ArticleDOI

Electron microscopy of plasmodium berghei. i. on the migration of trophozoites from infected erythrocytes in the rat.

01 Jul 1965-Transactions of The Royal Society of Tropical Medicine and Hygiene (No longer published by Elsevier)-Vol. 59, Iss: 4, pp 420-422
TL;DR: Electron microphotographs are presented of trophozoites of Plasmodium berghei migrating from parasitized rat erythrocytes, and the structure of the merozoite (young troPHozoite) is compared with that of the maturing trophozite containing pigment and forming rings.
Abstract: Electron microphotographs are presented of trophozoites of Plasmodium berghei migrating from parasitized rat erythrocytes. The structure of the merozoite (young trophozoite) is compared with that of the maturing trophozoite containing pigment and forming rings. The significance of trophozoite migration, regarding the extracellular viability and infectivity of the trophozoite form, remains to be investigated.
Citations
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Book ChapterDOI
01 Jan 1968

155 citations

Journal ArticleDOI
TL;DR: This sequence of events unequivocally establishes the origin of the parasite membrane envelope and theorigin of the space separating the two membranes.
Abstract: Entry of merozoites of Plasmodium berghei yoeli and of P. gallinaceum into erythrocytes has been elucidated by electron microscopy. Merozoites approach host cells with the conoid leading the way. At the point of contact between the anterior pole of the parasite and the host cell a focal depression of the red cell membrane forms, which deepens as the merozoite advances. The continuity of the host cell membrane is not disrupted. With deeper invagination of the red cell membrane the resulting cavity conforms to the shape of the merozoite. The site of initial parasite contact forms a relatively constricted orifice through which the posterior portion of the parasite passes. Later the edges of this orifice fuse and the parasite now lies in a vacuole inside the host cell. At this stage the merozoite undergoes a transformation and dedifferentiation. The pellicle loses the characteristic thick inner membrane. The parasite becomes rounded and the conoid and paired organelles are no longer discernible. Trophozoite d...

134 citations


Cites background from "Electron microscopy of plasmodium b..."

  • ...Ladda et al. (1965) found similar forms which were surrounded by two membranes and appeared to be leaving the red cell....

    [...]

Book ChapterDOI
TL;DR: The difference between the mitochondrial systems of intraerythrocytic species parasitized in mammals and those in birds is highly significant and serves as an example of the influence of the host on the fine structure of the parasite.
Abstract: Publisher Summary Plasmodium, the malaria parasite of mammals, birds, and reptiles, is among the most complex intracellular parasites. For its full development and survival in nature it requires two hosts, an invertebrate, in which its sexual reproduction takes place, and a vertebrate, in which it multiplies asexually. In the vertebrate host, plasmodium first invades cells of tissues of different organs before it enters erythrocytes, the main host cell; thus the latter phase is termed intraerythrocytic, and the former, exoerythrocytic. The difference between the mitochondrial systems of intraerythrocytic species parasitized in mammals and those in birds is highly significant and serves as an example of the influence of the host on the fine structure of the parasite. Bird malaria parasites have typical protozoan mitochondria, whereas mammalian plasmodia are deprived of such mitochondria and have a structure composed of concentric double membranes which presumably performs mitochondrial functions. The concentric double-membraned structures in plasmodium are derived from the plasma membrane.

53 citations

References
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Journal ArticleDOI
TL;DR: Among several heavy metal salts tested, the above-ment ioned " lead hydroxide" of Watson seemed to be the most effective in "s ta in ing ." Exper iments with the commercial ly available product showed that this salt would give no impregna t ion when dissolved in water, or in Institute.
Abstract: Meta l impregnat ion , or "s ta in ing ," of tissue sections for electron microscopy has become the accepted practice in recent years. Salts of metals of h igh atomic weight such as u ran ium, chromium, thor ium, lead, or tungsten, among many tested, have been found suitable (6, 1). "Lead hydroxide ," as prepar ted by Watson (6), is now widely used, hu t this solution is extremely unstable in air and becomes covered by a meta l l ic-appear ing film which imparts to the " s ta ined" section a well known deposit of e lectron-opaque particles and crystals, reducing considerably the percentage of clean areas suitable for micrography (Fig. l) . Several procedures and devices have been described to lessen these contaminat ions. Peachey (5), using lead hydroxide, or subacetate, found tha t if the solution is kept in a syringe with the protect ing cap filled with sodium hydroxide to absorb the CO2 of the atmosphere, con tamina t ion is reduced. More recently, a fairly unwieldy appara tus has been suggested for the same purpose (4). Tests performed in our laboratory in which " s t a in ing" was a t tempted in a chamber under cont inuous ni t rogen flow and in the presence of a ba r ium chloride t rap were not completely successful, which is to say tha t con tamina t ion cont inued to be a problem. A n u m b e r of o ther var iat ions have been recommended. Lever (2), e.g., described a method for prepar ing a " s t a in ing" solution by adding potassium hydroxide to a lead hydroxide solution. To dissolve some of the occasionally formed crystals of contamina t ion , the sections are rinsed afterwards for a few seconds in a weak potassium hydroxide solution; this step is very critical because the "s ta in ing" is also weakened by the alkali and uni form staining is difficult to achieve. These various shortcomings of current ly avai lable methods have st imulated us to search for a lead salt tha t would not be affected by the components of the atmosphere. Among several heavy metal salts tested, the above-ment ioned " lead hydroxide" of Watson seemed to be the most effective in "s ta in ing ." Exper iments with the commercial ly available product showed that this salt would give no impregna t ion when dissolved in water, or in Institute. Dr. Millonig's present address is Biological

1,310 citations

Journal ArticleDOI
TL;DR: It has been found that the rodent malarial parasite, Plasmodium berghei, is eliminated from the blood stream via the bronchial tree and is present in the tracheal washings of infected mice in macrophage cells, erythrocytes and also in the free state.
Abstract: It has been found that the rodent malarial parasite, Plasmodium berghei, is eliminated from the blood stream via the bronchial tree and is present in the tracheal washings of infected mice in macrophage cells, erythrocytes and also in the free state; and that these parasites are still viable and will give rise to the infection when injected into the peritoneal cavity of clean mice.

9 citations