内蒙古科尔沁草原绵羊不同虫龄土耳其斯坦东毕吸虫及虫卵孵化的实验观察

STRUCTURAL CHANGES IN DIFFERENT AGED WORMS OF ORIENT-OBILHARZIA TURKESTANICA OF SHEEP IN HORQIN PASTURE,OF INNER MONGOLIA,AND THE HATCHING PERIODICITY OF THE MIRACIDIA

作者在内蒙科尔沁草原实验观察了绵羊体内62日龄及三年龄的土耳其斯坦东毕吸虫雌雄虫。三年龄虫体变小,大多数雄虫的睾丸内质呈不同程度空泡伏,部分雌虫的卵巢和卵黄腺萎缩或消失,体形变异。实验羊粪便的虫卵孵化率逐年下降,粪便散入水中后连续4—5天有毛蚴孵出,毛蚴数最多的是在次日上午,随后每天上午有一递减的小高峰,下午极少、夜间消失。

Orientobilharzia turkestanica (Skrjabin, 1913 Srivastava, 1957), a blood fluke parasitizing the mesenteric and portal system of several species of ruminants in Asia and westward to France in Europe, has a wider distribution than that of Schistosoma japonicum. The present research is to invastigate the biological features of this trematode. Three uninfected lambs were used as experimental animals, and each of them was infected with considerable number of cercariae discharged from interior organ masses of 10 positive Radix auricularia and R. ovata. 46 days after infection, the three weakened lambs all passed mature eggs of O. turkestanica in their faeces. One lamb died in two months, the second died in three months after the infection. The third one which survived was kept in a place free of Orientobilharzia for three years, postmortem examinations of these sheep indicated that 93.75%-99.17% of worms recovered were found in the mesenteric veins and only 0.83%-6.25% in the portal vein.The faecal materials of the experimental sheep which survived 3 years were continuously examined. The number of miracidia hatching from the faeces decreased remarkably with the increase of duration of infection. It was concluded that as the Worms become older their gonads tend to degenerate and, hence, the number of eggs decreased. This was supported by the autopsy findings of the last sheep.Efforts were made to observe the hatching periodicity of the miracidia of 0. turkestanica. Altogether 65 grams of 40 faecal samples of the three experimental lambs were examined. The results indicated that a small number of miracidia hatched after the faeces were immersed in water for 2-3 hours. The number of miracidia diminished or vanished in the afternoon and night. In the forenoon of the second day, about 60%-70% of miracidia began to hatch. The number again decreased in the afternoon and then slopped hatching totally on the third, fourth and fifth day, there were still about 9%, 1% and 0.5% of miracidia hatching out respectively in the forenoon. Another experiment was conducted in a dark room and the similar phenomenon were noted. The last experiment was conducted under continuous artificial light irradiation for three days, under which large number of the eggs died. Those which remained alive, were found to be able to hatch out in each forenoon of the second and third day.