Studies on Intestinal Trematodes in Korea XV. Tegumental Ultrastructures of Fibricola seoulensis according to Developmental Stages

Abstract

Tegumental ultrastructures of FibricoJa seouJensis were studied by means of scanning electron microscopy according to their developmental stages. Metacercariae were obtained from the snakes, and the juvenile and adult worms were recoverd from small intestine of albino rats after experimental infection. Metacercariae revealed their characteristic spoon-shaped, ventrally concave body, and primordial stage of hindbody. External structures of oral sucker, ventral sucker and tribocytic organ were visible. Excretory pore was seen at postero-dorsal portion of subterminal body. Whole body surface was covered with simple, triangular spines. Uni-ciliated type I sensory papillae were distributed sparsely on whole surface but densely around oral and ventral suckers and peripheral margin. Round swellings, type II papillae, were recognizable but confined to lips of two suckers. More differentiated spines, 3-4 pointed ones, were seen in 2-day old juveniles, and primitive forms of the third type papillae appeared in 3-day old ones. In adults, hindbody had grown remarkably and revealed fine, velvety tegument. Tribocytic organ had stout recurved spines and honeycomb-like internal structures. Whole forebody was covered with serrated spines but hindbody was completely aspinous. But type III (round swellings without cilia) and type N (with cilia) sensory papillae appeared in hindbody. These papillae were suggested to be tango-, rheo- and/or chemoreceptive in function.