Dr. Éva Murai szerk.: Miscellanea Zoologica Hungarica 1. 1982 (Budapest, 1982)

Sey, O.: The morphology, life-cycle and geographical distribution of Paramphistomum cervi (Zeder, 1790) (Trematoda: Paramphistomata)

Redia The first free rediae emerged on the 13-15th days after infection. Young rediae measure 150-230 jam in length and 75-180 jim in width. During their further development they grow markedly and appear to reach their maximum when liberation of cercariae begins. The first mature rediae were perceived on the 15th day after liberation and their measurements were 700-1100 by 200-250 jam (Fig. 11). In the inner structure, a digestive system, a nervous system, an excretory system and a germinal tissue can be distinguished. The digestive system includes a mouth, a pharynx, an oesophagus and an unpaired gut. The mouth is a minute opening followed by the muscular pharynx, measuring 30-50 by 38-50 jum. The oesophagus is short, 15-20 jim in length, sourrounded by the so-called salivery glands and leading to the gut. The latter measures 75-125 urn in length and 50-80 urn in width. The centre of the nervous system is situated at the level of the oesophagus and it is very similar to that of the miracidium. The excretory system comprises three pairs of flame cells and their ducts which unite at about the middle of the body and they open to the outside through a small common bladder. The germinal system is situated in the second half of the young rediae consisting of the germinal epithelium, germinal cells and embryo balls. The latter develop gradually into cercariae. The birth pore becomes prominent only later, when young cercariae begin to accumulate in the first part of the body. The distance from the anterior body end is 300-320 urn. In about fifty days the signs of aging could be discerned (dirty grey and dark spots are found, body cavity is empty) and these rediae were gradually dying off. Cercaria Cercariae at birth are poorly developed; the first free cercariae were recovered on the 30-37th days after infection, measuring 250-375 urn with a tail appendage of 100-125 urn in length and 75-80 jam in width. The eye spots can already be seen when cercariae are within the redla. The first mature cercariae develop between the 45-55th days after infection. They are dark brown, quikly swimming organisms, with a body measuring 300-340 by 200-325 jam and tail 400500 by 65-75 jam. The body is covered with tegument, having cystogenous cells and rods. These rods make the body opaque, the scattered pigment granules lend a brown colour to the body. A pair of eyes are located on the dorsal surface of the mature cercaria, they are conical in shape. The acetabulum is situated at the posterior end on the ventral body surface, measuring 95-110 by 90-110 jam in living specimens (Fig. 12). The inner structure of the cercariae consists of the digestive system (pharynx, oesophagus, gut), excretory system (flame cells, ascending and descending excretory ducts, caudal exretory tube and bladder), nervous system and primordia of the reproductive system. The number of the flame cells was not detectable exactly due to the opacity of the body. Sensory papillae could be observed along the tail, twenty-five pairs were found in the region above the excretory pores and two pairs beyond it. Larval stages of P. cervi hibernate in the intermediate host (Planorbis planorbis

); in an endemic area of Hungary (Gemenc) 11.9% of P. planorbis

. born in the previous year, dissected at the end of April, 1975 contained fully developed cercariae. Metacercaria Shortly after emergence, the cercariae encyst on the vegetation (Fig. 13). The metacercariae are spherical in appearance, measuring 180-250 jam in diameter. Among environmental factors strong illumination stimulated emergence. Under low temperature (4-8°C) the life-span of metacercariae lasted for two-three months. Development in definitive hosts In order to determine the prepatent period of P. cervi

. a seven-month-old roe deer was infected with 2000, two-week-old metacercariae. Feacal samples were regularly controlled and the first eggs were found on the 85th day after infection. The percentage take was 42.3%. The prepatent period waB 96-130 days in cattle (N

KITIN, 1968; GLUZMAN, 1969; GLUZMAN & ARTEMENKO, 1969; MEREMINSKIÍ et al., 1971; KLESOV & MEREMINSKIÍ, 1973;