Metacercariae of Microphalloides japonicus were isolated from five kinds of crab which were collected at the Delta areas of Naktong river. These metacercariae were fed to experimental animals. Some of these metacercariae were also incubated in screw cap tube at 37 C. The longevity and developmental difference between flukes grown in vivo and in vitro were described. The total number of crabs examined were 2245 and Helice tridens tridens showed highest incidence among five species of brackish water crabs. Some of these metacercariae were fed experimentally to mice and rats, and the mature worms were obtained in the host intestine 24, 48, and 72 hours after infection. The adult and larval morphology of this fluke was described. Utilizing three kinds of medium, the adult worms of Microphalloides japonicus have been successfully developed under axenic conditions in vitro. Eggs containing adult worm were obtained in all of three media, i.e., Ringer's solution, Tyrode's solution, and Serum-Tyrode (1:1) solution. The adult worms were morphologically similar to flukes grown in vivo, but there were certain degree of difference between adult flukes grown in vivo and in vitro.
parasitology ; epidemiology-helminth ; trematoda ; Microphalloides japonicus ; metacercaria ; Helice tridens tridens ; Ringer's solution ; Tyrode's solution ; Serum-Tyrode (1:1) solution

Authors carried out the experimental study to investigate whether the Paragonimus westermani would uptake the blood in the parasitic definitive host, and also tried for the amount and distribution of the blood which would be harbored in a worm body, and so on. Experimental animals used in this study were dogs and cats, and they were infected with metacercariae of P. westermani. Several months later of the infection, Cr(51) tagged red blood cells were administered to each animal, and the animals were sacrificed and autopsy was done after 24 or 48 hrs of the administration. One part of the detected P. westermani adult worms of each animal were bred in Tyrode's solution and the others were killed by fixing in formalin solution. By Well-type scintillation counter, the radioactivities were measured for the alive and killed worms and of the blood of each experimental animal which was collected at autopsy . In conclusion, it was found that P. westermani worms uptake blood in parasitic definitive host, and amount of the blood harboring in a worm of 56 infection-days(size of worm; 4 x 3 x 1 mm) was 0.002 ml, 0.004 or 0.005 ml in 103 infection-days(size of worm: 8 x 5 x 3 mm) and 0.011 ml in 217 infection-days(size of worm: 9 x 7 x 4 mm). Almost of the whole blood uptaked in the worms was distributed in intestine. It was observed that the blood uptaked in the worm body was excreted continuously through the excretory pore, so that the radioactivity could not measured almost completely in cases of 24 hrs-breeding worms.
parasitology ; helminth ; trematoda ; Paragonimus westermani ; metabolism ; biochemistry ; red blood cell ; Cr(51) ; Tyrode's solution

Metacercariae of a kind of Levinseniella species were found from a brackish water crabs, Macrophthalmus japonicus de Haan, in the brackish area of Hyungsan river of Kyungpook province. Habitats were the epigastric and progastric regions of Macrophthalmus japonicus. One hundred and seventy five crabs out of 178 examined (98.3 per cent) were infested with metacercariae of Levinseniella species. The infested number of metacercariae in each crabs was average 100 ea. The excystation of metacercaria has not developed in vitro (both saline and tyrode's solution). Many eggs were observed in the metacercariae maintained for 24 or 48 hours in the water-bath. No differences were observed between semi-adult fluke from rat host and those maintained for 24 or 48 hours in vitro.
parasitology-helminth-trematode ; Levinseniella ; Macrophthalmus japonicus ; crab ; epidemiology ; tyrode's solution ; saline

A series of experiments on various factors which induce optimal in vitro excystation of the metacercariae of Metagonimus yokogawai isolated from the fish, Plecoglossus altivelis was conducted and the following results were obtained. The metacercariae used in this experiment were isolated by the digestion technique therefore all of them were pretreated with the acid-pepsin solution before being applied to the various tests. No excystation occurred when the metacercariae were placed in a salt solutions such as physiological saline, Tyrode solution and Veronal, Tris buffers alone or in combination. The metacercariae underwent complete excystation in the trypsin and pancreatin solution in Tris buffer within an hour at 38 degrees C. The best results were obtained in 0.8-0.9% trypsin solutions, pH 8.0-8.6 and at 38-40 degrees C, approximately one hundred per cent excystation occurred in 40 minutes. Not only temperature but also hydrogen ion concentration played an important role causing excystation of the metacercariae in trypsin-Tris buffer solution. However, bile salts were not responsible for the excystation. Agitation effect on the excystation was tested as a mechanical stimulus and it was found that the shaking stimulus accelerated the excysting mechanism, compared with the metacercariae on which it was not imposed. It is concluded that the metacercariae pretreated in the acid pepsin solution demonstrates an essential requirement for the enzyme solution such as trypsin or pancreatin, provided with the optimum conditions of temperature and hydrogen ion concentration in excysting medium.
parasitology-helminth-trematoda-Metagonimus yokogawai ; metacerecaria-excystation ; bioloygy ; physiological saline ; Tyrode solution ; Veronal buffer ; Tris buffer ; trypsin ; pancreatin ; trypsin-Tris buffer