[Development of mother sporocysts of Echinostoma caproni (Trematoda: Echinostomatidae)].

New data on the migration and development of Echinostoma caproni mother sporocysts in two mollusk species of the genus Biomphalaria are obtained. It is confirmed, that the formation of primary and second generative cells takes place only as a result of undifferentiated cells' proliferation and following differentiation of some of them. These processes in miracidium, as well as in the parasitic stage of mother sporocyst, take place in a special organ, germinal mass, which occupies caudal position in both cases. The supposition of the role of germinal mass as the universal centre of multiplication and development of generative elements in all generations of Echinostoma caproni parthenites is confirmed. It is established, that mother sporocysts do not relize their reproductive potential completely, and the degree of its realization depends on the conditions arising in the host organism.

Studies on the life cycle of Artyfechinostomum oraoni Bandyopadhyay, Manna & Nandy 1989: embryogenesis & development in the intermediate host.

A study was undertaken to elucidate the life cycle of the parasite A.oraoni, isolated from man. For the purpose, operculated eggs were isolated from faeces of oraon tribals belonging to the village Bandipore, district North 24-Parganas of West Bengal province of India. The purified eggs were incubated at different temperatures, salinity and pH. Larvae (miracidia) could be observed to develop between the 7th and 8th day of incubation at a temperature range between 22 degrees-30 degrees C. While the optimum pH was observed to be neutral, larval development did not take place at salinity beyond 0.8 per cent. To identify the correct intermediate host, all available species of snails from the study village were colonised and infected with the laboratory hatched miracidia from human derived operculated eggs. It was observed that of all the snails infected, only Lymnaea supported the development of rediae from miracidia, which could be observed on the 32nd post infection day. Considering the results of the experimental study, it was hypothesised that Lymnaea spp. of snails under natural condition also, might act as the first intermediate host for A. oraoni.

Hatching of Echinostoma caproni miracidia from eggs derived from adults grown in hamsters and mice.

Echinostoma caproni eggs developed fully formed miracidia from hamster-source eggs in 9 days and from mouse-source eggs in 10 days under either light or dark conditions at 27 degrees C. Incubation of egg cultures under constant light resulted in miracidial hatching from hamster-source eggs in 11 days and from mouse-source eggs in 13 days. Exposure to light was essential to trigger hatching, with incandescent light providing more consistent stimulation than fluorescent light. A majority of the miracidia hatched at between 1100 and 1600 hours, indicating a diurnal circadian pattern. Eggs stored in a dark environment for 11 days required 6 days to reach maximal hatching after exposure to light. Eggs stored for 46 and 56 days hatched on the same day of their exposure to light. Miracidia that hatched after 56 days of dark storage exhibited aberrant swimming behavior; those stored in a dark environment for 70 days or longer did not hatch when exposed to light.