Dr. Murai Éva - Gubányi András szerk.: Parasitologia Hungarica 27. (Budapest, 1994)

adult is quite significant as several functions have been assigned to this enzyme in helminths. Nizami et al. (1977) reported that digenetic trematodes secrete appreciable quantities of acetylcholinesterase under in vitro conditions and suggested that AChE secretion is a biochemical adaptation in order to prevent expulsion from the host. A similar hypothesis has been proposed for nematodes (Lee 1970, Sanderson and Ogilvie 1971, Sanderson 1972, Barrett 1981). However, AChE is known to be involved in neurotransmission and has been reported as the degrading enzyme in cholinergic transmission in Fasciola hepatica (Sukhdeo et al. 1988). Moreover, some workers reported that acetylcholinesterase is also responsible for the stimulation of the immune responses of the host (Edwards et al. 1971, Jones and Ogilvie (1972). In view of the above-mentioned functional aspect of AChE in helminths, it may be possible that this enzyme plays some role in the establishment of the host-parasite relationship. Under experimental conditions this parasite survives 6-7 days in the buccal cavity of chickens and thereafter infection disappears (Kalantan et al. 1991). The lifespan of C. complanatum in the buccal cavity of herons is about 14 days (Cheng 1973). Thus it seems that in the early phase of infection this enzyme helps in establishing a biochemical holdfast and later it stimulates the immune responses to reject the parasite from the host because the disappearance of adult C. complanatum from the experimental host has been attributed to the acquired immunity, and heavy infiltration by polymorphonuclear leucocytes and fibroblast cells at the site of parasite attachment have also been observed (see Kalantan et al. 1991). Thus, the presence of various proteins and enzymes suggests that the forebody glands of C. complanatum are basically involved in the synthesis of proteinaceous substances which may be utilized for growth during the transformation of metacercaria into adult. Further, acetylcholinesterase may help in establishing a biochemical holdfast with the host, which in the later stages may stimulate the immune responses of the host to an extent sufficient for dislodging the parasites. However, further biochemical and ultrastructural studies are required to confirm these functions. ACKNOWLEDGEMENT The authors are grateful to the Chairman of the Zoology Department for providing laboratory facilities. Kalantan, A. M. N., Arfin, M. és Nizami, W.A.: Hisztokémiai vizsgálatok a Clinostomum complanatum (Rudolphi 1819) meta ter kúriájának és aduitusainak feji mirigyein A szerzők hisztokémiai módszerekkel tanulmányozták a Clinostomum complanatum (Trematoda) metacerkáriáinak és aduitusának feji mirigyeit. A mirigyek egysejtűeknek bizonyultak, és savas mukopoliszaharidokat, bázisos proteineket, ditirozint, elasztint, fíbrint, glikogént, keratinszerű proteineket, tirozint és ribonukleinsavat tartalmaztak. A mérsékelten savastól az erősen savas és alkalikus foszfatázig, acetilkolineszteráz és nem specifikus eszteráz aktivitás volt mérhető. A szerzők a mirigyek kiválasztási produktumainak lehetséges funkcionális hatását értékelik.