Fried B, Frazer B A, Kanev I
Department of Biology, Lafayette College, Easton, Pennsylvania 18042, USA.
J Parasitol. 1998 Jun;84(3):623-6.
Comparative observations were made on cercariae of Echinoparyphium sp. from Physa gyrina in Charlie's pond, Stokes County, North Carolina and cercariae of Echinostoma trivolvis from Helisoma trivolvis in Northampton County, Pennsylvania. The cercaria of Echinoparyphium sp. has 43 collar spines, lacks penetration and paraesophageal glands, and has a conical tail without fin folds. The cercaria of E. trivolvis has 37 collar spines, penetration and paraesophageal glands, a finger-like process at the tip of the tail and fin folds. The length of the cercarial body and tail of E. trivolvis was significantly greater than that of Echinoparyphium sp. Cercariae of both species encysted in Biomphalaria glabrata snails in single and concurrent infections. In concurrent infections with a single cercaria of each species, 2 encysted metacercariae were adjacent to each other in the saccular kidney of the snail at 24 hr postinfection. The diameter of encysted metacercariae of E. trivolvis was significantly greater than that of Echinoparyphium sp. Echinoparyphium sp. metacercariae excysted at 39 C in an alkaline trypsin-bile salts medium used previously to excyst E. trivolvis. The length of excysted metacercariae of E. trivolvis was significantly greater than that of Echinoparyphium sp.
对采自北卡罗来纳州斯托克斯县查理池塘的旋螺体内的棘口属吸虫尾蚴，以及宾夕法尼亚州北安普敦县的静水椎实螺体内的三歧棘口吸虫尾蚴进行了比较观察。棘口属吸虫尾蚴有43根颈部棘刺，无穿刺腺和食管旁腺，尾部呈圆锥形，无鳍褶。三歧棘口吸虫尾蚴有37根颈部棘刺，有穿刺腺和食管旁腺，尾尖有一指状突起和鳍褶。三歧棘口吸虫尾蚴的虫体和尾部长度显著大于棘口属吸虫尾蚴。两种尾蚴均可在光滑双脐螺体内单独或同时感染时形成囊蚴。在每种尾蚴各单条同时感染时，感染后24小时，在螺的囊状肾内，2个囊蚴彼此相邻。三歧棘口吸虫囊蚴的直径显著大于棘口属吸虫囊蚴。棘口属吸虫囊蚴在先前用于三歧棘口吸虫脱囊的碱性胰蛋白酶 - 胆盐培养基中于39℃脱囊。三歧棘口吸虫脱囊后尾蚴的长度显著大于棘口属吸虫脱囊后尾蚴的长度。
