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The value of staining old, unstained thick and thin blood films of malaria parasites with Giemsa diluted with saline instead of distilled water
467
(The previous number of these Transactions, Vol. 64, No. 3, was published on lst June, 1970). ROYAL SOCIETY OF TROPICAL MEDICINE AND HYGIENE L A B O R A T O R Y MEETING
Royal A r m y Medical College, M i l l b a n k , London, Thursday, 19 March, 1970
The President : PROFESSORB. G. MAEGRAITH,C.M.G., M.A., M.B., B.S., D.SC., D.PHIL.~ F.R.C.P., F.R.C.P.E. in the Chair DEMONSTRATIONS PROTOZOOLOGY
AND PROTOZOAL
DISEASES
The value of staining old, unstained thick and thin blood films o f malaria parasites with Giemsa diluted with saline instead of distilled water P. G. S H U T E AND M. M A R Y O N
Malaria Reference Laboratories, Horton Hospital Specimens of blood films of malaria parasites, both thick and thin, showing the advantages of diluting Giemsa stain with normal saline instead of distilled water.
Electron microscope studies on the pre-erythrocytic stages o f rodent m a l a r i a J. M. B A F O R T * AND R. E. H O W E L L S t
*Antwerp Institute of Tropical Medicine t Liverpool School of Tropical Medicine The fine structure of immature pre-erythrocytic schizonts of P. berghei and P. vinckei has been investigated in the liver of their natural host, Thamnomys surdaster. A marked similarity to the process of development of the malarial o6cyst has been observed. Growth of the schizont is associated with the formation of pseudocytomeres and rnerozoite budding takes place along the surface of these. The liver schizonts of P. berghei and P. vinchei differ from the o6cysts in possessing acristate mitochondria. In only one schizont of P. berghei, which also possessed unusually large numbers of lipid droplets, cristate mitochondria were observed. T h e latter is considered an abnormal feature. T h e preerythrocytic schizont lies within a liver parenchymal cell. The host cell cytoplasm and the plasma membrane of the schizont are separated by a fibrous layer which may be of host or parasite origin. A considerable degree of involution of this layer may be observed, giving a "placenta-like" appearance to the host-parasite interface. Grateful acknowledgements are due to Professor I. H. Vincke, Professor W. Peters, Mr. A. Oaldey, Mrs. E. Ousby, the Wellcome Trust, Beecham Laboratories Ltd., and World Health Organization, for assistance and support.
Rapid production of mepacrine resistance in rodent malaria K. G. G R E G O R Y
Liverpool School of Tropical Medicine A derivative of the berghei-like parasite, strain N67 (KILLICK-KE~RmK et al., 1968) was maintained by serial blood passage in male 20 g. T F W mice treated with mepacrine methanesulphonate (given as an intermittent subcutaneous dose of 100 mg./kg, in 0"2 rrd. aqueous solution), and by cyclical transmission through Anopheles stephensi at 25°C. Judged by the course of the erythrocytic parasitaemia, the derivative (termed M G ) rapidly developed tolerance to treatment. After three successive blood passages it was tested for sensitivity to mepacrine using the bioassay technique of Warhurst & Folwell (1968). The asexual intra-erythrocytic forms were found to be almost totally resistant to 100 mg./kg., compared with the parent strain which was sensitive to doses of 20 mg./kg, and above. During and for some time after treatment, all erythrocytic forms of the derivative line lacked or showed reduced pigmentation, as described by PETERS (1966). Apparent apigmented gametocytes were seen after the second blood passage, but although exflagella-
(The previous number of these Transactions, Vol. 64, No. 3, was published on lst June, 1970). ROYAL SOCIETY OF TROPICAL MEDICINE AND HYGIENE L A B O R A T O R Y MEETING
Royal A r m y Medical College, M i l l b a n k , London, Thursday, 19 March, 1970
The President : PROFESSORB. G. MAEGRAITH,C.M.G., M.A., M.B., B.S., D.SC., D.PHIL.~ F.R.C.P., F.R.C.P.E. in the Chair DEMONSTRATIONS PROTOZOOLOGY
AND PROTOZOAL
DISEASES
The value of staining old, unstained thick and thin blood films o f malaria parasites with Giemsa diluted with saline instead of distilled water P. G. S H U T E AND M. M A R Y O N
Malaria Reference Laboratories, Horton Hospital Specimens of blood films of malaria parasites, both thick and thin, showing the advantages of diluting Giemsa stain with normal saline instead of distilled water.
Electron microscope studies on the pre-erythrocytic stages o f rodent m a l a r i a J. M. B A F O R T * AND R. E. H O W E L L S t
*Antwerp Institute of Tropical Medicine t Liverpool School of Tropical Medicine The fine structure of immature pre-erythrocytic schizonts of P. berghei and P. vinckei has been investigated in the liver of their natural host, Thamnomys surdaster. A marked similarity to the process of development of the malarial o6cyst has been observed. Growth of the schizont is associated with the formation of pseudocytomeres and rnerozoite budding takes place along the surface of these. The liver schizonts of P. berghei and P. vinchei differ from the o6cysts in possessing acristate mitochondria. In only one schizont of P. berghei, which also possessed unusually large numbers of lipid droplets, cristate mitochondria were observed. T h e latter is considered an abnormal feature. T h e preerythrocytic schizont lies within a liver parenchymal cell. The host cell cytoplasm and the plasma membrane of the schizont are separated by a fibrous layer which may be of host or parasite origin. A considerable degree of involution of this layer may be observed, giving a "placenta-like" appearance to the host-parasite interface. Grateful acknowledgements are due to Professor I. H. Vincke, Professor W. Peters, Mr. A. Oaldey, Mrs. E. Ousby, the Wellcome Trust, Beecham Laboratories Ltd., and World Health Organization, for assistance and support.
Rapid production of mepacrine resistance in rodent malaria K. G. G R E G O R Y
Liverpool School of Tropical Medicine A derivative of the berghei-like parasite, strain N67 (KILLICK-KE~RmK et al., 1968) was maintained by serial blood passage in male 20 g. T F W mice treated with mepacrine methanesulphonate (given as an intermittent subcutaneous dose of 100 mg./kg, in 0"2 rrd. aqueous solution), and by cyclical transmission through Anopheles stephensi at 25°C. Judged by the course of the erythrocytic parasitaemia, the derivative (termed M G ) rapidly developed tolerance to treatment. After three successive blood passages it was tested for sensitivity to mepacrine using the bioassay technique of Warhurst & Folwell (1968). The asexual intra-erythrocytic forms were found to be almost totally resistant to 100 mg./kg., compared with the parent strain which was sensitive to doses of 20 mg./kg, and above. During and for some time after treatment, all erythrocytic forms of the derivative line lacked or showed reduced pigmentation, as described by PETERS (1966). Apparent apigmented gametocytes were seen after the second blood passage, but although exflagella-