The growth and development of Pygidiopsis summa were studied in experimental rats and mice, and a special reference was given to its morphological characters differed from the type species, P. genata. The metacercariae were obtained from young mullets (Mugil sp.), and total 21 rats and mice infected each with 1,000 metacercariae. Worms of various ages of infection, from 3 to 28 days, were subjected to a microscopic observation. The worms grew rapidly and remarkably in size up to 10 days of infection, to become 0.53-0.82 mm long and 0.31-0.39 mm wide, but nearly stopped the growth thereafter. Their genital organs developed more rapidly and fully matured within 3-5 days. At 3 days several eggs were found in uterus. The presence of two groups of small spines, 5-6 on the right and 7-9 on the left side of the genital apparatus, was a new finding in this study and considered a distinct character of P. summa. The morphology of ventral sucker and intestinal ceca was also different from P. genata. This study confirms the validity of the species, P. summa.
parasitology-helminth-trematoda ; Pygidiopsis summa ; morphology ; development ; rat

During 8 april 1983 to 9 April 1985, a total of 181 domestic cats (Felis catus domestica Linnaeus) of unknown localities in Korea were purchased at Seoul Chung-ang market, and the internal organs were dissected for helminth infections. In the results, three kinds of trematodes of family Heterophyidae (Ohdner, 1914) were obtained from small intesine of domestic cats and identified as follows: five adult worms of Heterophyopsis continua (Onji et Nishio, 1916) from three hosts, two hundreds and twenty three adult worms of Pygidiopsis summa Onji et Nishio, 1916 from seven hosts and twenty six adult worms of Heterophyes heterophyes nocens (Onji et Nishio, 1916) from three hosts. Among them, Heterophyopsis continua and Pygidiopsis summa had not been proved as natural infectios of cats in Korea.
parasitology-helminth-trematoda ; Heterophyidae ; Heterophyopsis continua ; Pygidiopsis summa ; Heterophyes heterophyes nocens ; cat ; animal

In order to provide some clues for differential diagnosis of trematode infections in fecal examination, the comparative morphology of eggs of 5 kinds of heterophyid flukes (Metagonimus yokogawai, Heterophyes heterophyes nocens, Heterophyopsis continua, Stellantchasmus falcatus and Pygidiopsis summa) and Clonorchis sinensis was studied. The eggs were obtained from distal portion of uteri of worms which were recovered from men after treatment. The characteristic shape and apperance of each kind of eggs were observed in detail under light microscope, and their length and width measured and compared one another. The results are as follows: Eggs of C. sinensis are elongated ovoidal in shape with attenuated anterior end, 25.3-33.2 (28.3 in average) micrometer long and 14.2-17.4(15.9) micrometer wide with length /width ratio of 1.60-2.00 (1.78). They differ from all heterophyid eggs in that they have prominent wrinkling (muskmelon pattern) at their shell surface. P. summa eggs are ovoid to pyriform in shape and characterized by the smallest size of all kinds examined, 19.8-22.9(21.6) micrometer long and 11.1-13.4 (12.1) micrometer wide and the ratio 1.63-1.99 (1.78). Eggs of S. falcatus are elongated ovoidal and most slender form, 25.3-29.2 (27.2) micrometer long and 11.1-13.4 (12.5) micrometer wide with the ratio of 2.00-2.57 (2.17). Eggs of M. yokogawai are ellipsoid to elliptical in shape with round both ends, 26.9-31.6 (28.5) micrometer long and 14.2-18.2 (16.8) micrometer wide with the ratio of 1.48-2.11(1.70). H. continua eggs are oval in shape, sometimes similar to M. yokogawai or H. h. nocens eggs, however, the relative breadth is broadest among all kinds, with maximum width at posterior half portion. They are 23.7-27.7 (25.0) micrometer long, 15.8-18.9 (16.4) micrometer wide with the ratio of 1.33-1.75 (1.53). Eggs of H. h. nocens are ellipsoid to ovoid in shape but sometimes more slender than M. yokogawai and have slightly pointed both ends. They are 23.7-29.2 (25.7) micrometer long, 14.2-15.8 (15.4) micrometer wide, and the ratio 1.50-2.06 (1.67). From the results, it is concluded that eggs of 5 kinds of heterophyids and C. sinensis can be morphologically differentiated one another, however, careful observation and measurement on sufficient number of eggs are needed.
parasitology-helminth-trematoda ; Clonorchis sinensis ; morphology ; egg ; Metagonimus yokogawai ; Heterophyes heterophyes nocens ; Heterophyopsis continua ; Stellantchasmus falcatus ; Pygidiopsis summa