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M Rommel

Publications and source records attributed to M Rommel.

At least 73 records · Page 4Linked to original sources
PubMed1978

[Investigations into the fire structure of the asexual developmental stages of Frenkelia in the liver of the bank vole (author's transl)].

Bank voles (Clethrionomys glareolus) were infected by stomach tube with Frenkelia sporocysts from the faeces of buzzards (Buteo buteo). The voles were sacrificed at regular intervals and their livers examined electronmicroscopically. Seven days p.i. developmental stages of Frenkelia could be detected in liver parenchymal cells. The youngest schizonts detected are enveloped by a pellicle consisting of two membranes. This pellicle, which is in direct contact with the host cell mitochondria, shows marked invaginations which increase with the development of the schizont. A parasitophorous vacuole is not detectable. In developing schizonts numerous sections through nuclei with nucleic spindles and merozoite anlagen (dome-shaped) structures) are visible. It is not clear whether there are several nuclei or a section through one large and lobed nucleus. Within the merozoite anlagen the conoid and the subpellicular microtubules are formed first. By the prolongation of the dome-shaped structures towards the posterior pole, the nucleus and the other newly formed cell organelles are incorporated into the forming merozoite. The posterior pole of the merozoite still remains open at this stage of development. With increasing differentiation the merozoites become lancet-shaped, their apical poles bing always directed towards the periphery of the schizont. The outer membrane of the pellicle of the schizont forms the outer part of the pellicle of the merozoites by invaginating around them. At this stage of development the inner membrane of the pellicle of the schizont is no longer detectable. Thus the typical pellicle of the motile stages of sporozoaonsisting of three membranes is formed. In the centre of the merozoites which lie freely in the liver cell a residual body is present. The host cell reacts against the parasites by forming a thick border of mitochondria and distinct endoplasmic reticulum.

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PubMed1978

[Life cycle of Frenkelia. IV. Pathomorphological findings in the organs of experimentally infected bank voles].

In 1975 the buzzard (Buteo buteo) was found to be the final host of Frenkelia clethrionomyobuteonis. After this discovery it became possible to investigate systematically the pathomorphology of the infection in the intermediate host, the bank vole (Clethrionomys glareolus). Fifty bank voles were infected orally with a suspension of sporocysts recovered from the faeces of experimentally infected buzzards. Each rodent receive 7000 sporocysts. Six controls each were given a faecal suspension from a non-infected buzzard. The voles were killed between 1 and 140 days after infection and examined histologically. Between the 5th and 8th day of the infection during the schizogonic multiplication of the parasite a focal necrosis of liver cells and of the liver parenchyma is observed followed by a reversible resorptive inflammation associated with siderophagia and the occurrence of giant cells. The spleen was spodogenously enlarged up to twice its normal size. There also was haemosiderosis of the bone marrow, the liver and the spleen up to 25 days after infection. At the same time the erythropoiesis in the bone morrow, the spleen and in the lymph nodes increased; there also was a lymphoid hyperplasia in spleen and lymph nodes. About 10 days after infection a reversible infiltration with lymphocytes and plasma cells developed in the liver, heart and brain. This infiltration was again detectable as perivascular and meningeal reactions in the brain after the 49th day after infection. The second asexual multiplication of the parasite was seen histologically in the grey and white matter of the central nervous system after the 18th day of infection. The developing cysts increased in size continuously thereby compressing the surrounding nervous tissue. Disseminated focal necrosis with resorptive inflammatory components was prominent in the parenchyma of the brain after the 49th day of infection. It was possible to differentiate between damage in single organs and systemic pathological lesions. The lesions in single organs were directly connected with the development of parasitic stages in the liver (schizonts) and in the brain (cysts). The generalized lesions occurred in the haemopoietic system after an impairment of the blood during the first asexual multiplication. They also occurred in the immunocytic systems after the first and during the second asexual multiplication and during the relatively late cystic phase of the parasite in the brain. The pathogenesis of the disintegration of blood cells is not clear. The immunocytic reaction can be considered an immunological response of the host against the parasite. The effect of the development of the cysts on the function and structure of the central nervous system is expected to lead to an increasing impairment of the motility of the intermediate host.

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PubMed1977

[Contributions to the life-cycle of Frenkelia. III. The sexual development of F. clethrionomyobuteonis in the buzzard (author's transl)].

8 buzzards (Buteo buteo) were infected orally with cysts of Frenkelia clethrionomyobuteonis of the bank vole (Clethrionomys glareolus). Their intestines were searched for developmental stages of Frenkelia 21 and 24 h and 2, 3, 4, and 5 days post infection. After 21 and 24 h male and female gamonts could be detected within epithelial cells of the villi of the first half of the small intestine. The microgamonts contained 10-14 microgametes. The macrogamonts which measured on an average 11,1 X 9,8 mum in Giemsa stained smears developed into very thin-walled oocysts measuring in fresh preparations on an average 15,8 X 11,7 mum on day 3 after infection. The oocysts were located between the lamina propria and the epithelial lining of the distal third of the villi. They began to sporulate on day 5 and the first sporocysts were excreted 7 and 8 days post infection. Schizonts and schizont-like stages could not be observed in the developmental cycle in Buteo buteo.

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PubMed1976

[Contributions to the life-cycle of Frenkelia. II. The asexual development of Frenkelia clethrionomyobuteonis in the bank vole (author's transl)].

A description of the asexual development of Frenkelia clethrionomyobuteonis in the European bank vole (Clethrionomys glareolus) is given as observed in experimental infections with sporocysts from buzzards' faeces. Between the 5th and the 8th day following the oral administration of sporocysts a first schizogony could be observed in liver parenchymal cells of the mammalian host. In impression smears the banana-shaped merozoites measured on an average 7.6 X 2.2 mum. Only after the 18th day were small round cysts filled with metrocytes detected in the brain and spinal cord. During the first month after infection the cysts increased their size only gradually measuring 15 to 40 mum. After 2 months they accelerated their growth and reached in the course of 3-4 months a diameter of 300 to 400 mum. Cyst formation could not be observed in organs other than the central nervous system. Cysts older than half a year frequently showed central degeneration, but in all cases viable cystozoites persisted in the peripheral zones. The infection could be transmitted from vole to vole by intraperitoneal injection of merozoites in a suspension of liver cells from the 7th day p.i. Congential infections did not occur in the offspring of mothers infected during or before pregnancy. The infectivity of the final products of the sexual development in the buzzard is limited to the bank vole.

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