Evagination of Taenia solium cysticerci: A histologic and electron microscopy study

Background, After a human being ingests a cysticercus, the larval stage of Taenia solium, the cysticercus gradually develops toward the adult parasite . In this paper, we describe the sequential progress of evagination of cyst icerci. Methods. Intact cysticerci were obtained from swine muscle, and incubated i n bovine bile to stimulate evagination. Dissecting, light, and electron mic roscopy of whole parasites and histologic sections were used for photograph ic registers. Results. The first event was the widening of the opening of the bladder wal l for the scolex and neck to emerge. The two chambers that conform the cyst icercus were identified. Histologic sections provided explanation for the c onformation of the spiral canal. Conclusions. The scolex uncoils during evagination but does not turn inside out. The scolex and the neck comprise a different structure from the bladd er wall, although they are contiguous. (C) 2001 IMSS. Published by Elsevier Science Inc.