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)
Miracidium The hatched and free-swimming miracidium is fusiform without eye spot, covered with cilia (Fig. 8). The measurements of the living miracidia: 175-200 by 40-50 jim, the fiexed ones are 120-125 by 55-58 p.m. The body is covered with flat epidermal cells in four transverse rows according to the formula 6:8:4:1 (Fig. 9). At the anterior end of the miracidium lies the ciiium-free terebratorium with argentophilic structures. They are situated along three axes, Tj = 5, T2 = 14, T3 = 10; a further 12 similar structures can be found along the body, 10 of them between the first and the second epidermal cell rows and two between the second and the third ones. The inner miracidial structure consists of the apical gland, the penetration glands, the nervous system, the excretory ducts and the germinal tissue, similar to that of other miracidia of rumen flukes (LENGY, 1960; SEY, 1979a). The life-span of miracidia kept in tap water at room temperature was 10-12 hours but their virulence limited to the first four hours only. Intermediate hosts and infectional experiments Several sets of infections were performed with young (2-3 weeks old) Planorbis planorbis under room temperature (20-22°^). Two-five miracidia were added to snails kept in water individually in the hollows of a microtiter plastic plate. Infection was successful in 75-90% of the snails thus treated. Three hundred of young specimens (2-3 weeks old) of Bulinus truncatus were also infected by the same method with miracidia of P. cervi . These snails suffered no infestation indicating that the miracidia of P. cervi are not susceptible to this snails. According to literary data (SZIDAT, 1936; KRYUKOVA, 1957; WILLMOTT & PESTER, 1955; ZDUN, 1958; NIKITTN, 1968; GLUZMAN, 1969; MEREMINSKII et al., 1971; ASADOV et al., 1972; KATKOV, 1973; KRANEBURG, 1977; KRANEBURG & BOCH, 1978; ODENING et al.. 1978; ODENING et al.,1979) the following pianorbid snails have been recorded as intermediate hosts: AnisuB leucostomus , A. spirorbis, A. septemgiratus, A. vortex, Argimer crista , A. inermis, BathyomphaluB contortus, Choanophalus anophalus, Gyraulus albus, G. gredleri, G. elenbergi, Hippeutis complanatus , Planorbis carinatus , P. planorbis and Segmentina nitida. Susceptibility of P. cervi to different planorbid snails and the unsuccessful experiments with Bulinus truncatus as well as the resistence to other than planorbids (Lymnaea , Physa. Radix. ODENING et al.,1979) allow us to support that LOOSS (1896), GRETILLAT (1958) and ABDELGHANI (1961), who indicated bulinid snails in their life-cycle studies, in fact had worked with other species of flukes, probably with P. microbothrium which is a common rumen fluke of that area (SWART, 1954; PRUD'HON et al., 1968; SEY, 1976, 1977; SEY & ABDEL-RAHMAN, 1975) and of which intermediate hosts are bulinid snails. KRULL's (1933) species has probably been other than P. cervi because the intermediate hosts listed by him are lymnaeid snails. Intramolluscan larval stages Sporocyst After penetration, the invading miracidium continues its development in the snail tissue; undergoing noticable changes: shedding of epidermal plates, losing some internal structures (apical papilla, apical and penetration glands) and breaking down of embryo balls into separate germinal cells (Fig. 10). The sporocyst shows a marked increase in size; e.g. the four-day-old specimen measures 160-170 by 140-150 jam; it reaches maturity in 10-15 days. NIKITIN (1968) and KRANEBURG (1977) indicated longer periods of maturation while GLUZMAN' s (1969) findings agree with our observations. Mature sporocyts are located in the body cavity of the snail, along the digestive truct; it is covered by a thin, transparent envelope and contains some fully developed rediae and numerous embryo balls. One pair of flame cells was found in the sporocyst; neither the process of liberation of the rediae nor the opening of the sporocyst' s surface were observed.
