Ultrastructure of the pseudophyllidean cestode Botriocephalus Acheilognathi, parasite of freshwater fish of commercial importance

Abstract

THE ULTRASTRUCTURAL MORPHOLOGY OF THE CESTODE BOTHRIOCEPHALUS ACHEILOGNATHY ( YAMAGUTI, 1934) HAS BEEN STUDIED BY SEM ( SCANNING ELECTRON MICROSCOPY) AND PRINCIPALLY BY TEM ( TRANSMISSION ELECTRON MICROSCOPY ). THIS PARASITE WAS ISOLATED FROM THE GRASS CARP CTENOPHARYNGODON IDELLUS FROM FRESH WATER PONDS AND SATER LOCKS IN TWO STATES OF MEXICO ( QUERETARO AND HIDALGO). ADULT B. ACHEILOGNATHI RANGED FROM 3.5 TO 13.5CM LONG AND 0.36 TO 1.44 MM WIDE. THIS CESTODE PRESENTS THREE TYPES OF MICROTRICHES: THE FIRST TYPE CORRESPONDS TO A LARGE AND THIN STRUCTURE, THE SECOND TYPE IS SHORT AND WIDE, BOTH TYPES ARE FOUND ON THE SCOLEX AND THE STROBILA. THE THIRD TYPE IS OBSERVED EXCLUIVELY AT THE BOTTOM OF THE BOTHRIA AND IS LARGER AND THINNER THAN THE FIRST TYPE. SENSILLA ARE LOCATED AT THE LTEGUMENT SURFACE. THESE SENSITIVE ORGANS ARE DISTRIBUTED ON THE SCOLEX AND STROBILA; THEIR CILIA NEVER PROTRUDE HIGHER THAN THE SURROUNDING MICROTRICHES. THE BULB OF THE SENSILLA IS CONECTED TO THE DYSTAL CYTOPLASM BY SEPTATE DESMOSOMES AND A SINGLE ELECTODENSE COLLAR. OTHER STRUCTURES ORIGINATED AT THE UNICELLULAR GLANDS OF THE PERINUCLEAR CY TOPLASM. MUSCLE BUNDLES ARE PRESENT IN THE PERINUCLEAR REGION BELOW THE BASAL MEMBRANE. THESE SMOOTH MUSCLE FIBERS PRESENT TWO ORIENTATIONS. BETWEEN THE MUSCULAR ZONE AND PERINUCLEAR CYTOPLASM THERE IS AN INTERMEDIATE ZONE CLEARLY OBSERVALBLE AT THE SCOLEX AND LESS DEFINED BUT PRESENT AT THE PROGLOTTIDS. THIS ZONE IS PACKED WITH CITOPASMIC PROJECTIONS, WICH CONTAIN RABDIFORM BODIES, MITHOCONDRIA AND ABUNDANT GLYCOGEN. THE GOLGI BODIES INDICATE A CELL ACTIVELY SECRETING PROTEINS. IN THE REGION OR THE PERINUCLEAR CYTOPLASM, IN ADDITION TO THE UNICELULLULAR GLANDS AND THE MOCUUS SECRETORY CELL, THE MAIN ORGANS ARE VITEGENIC GLANDS, PROTHOIRIDIAL SYSTEM, GONADS AND THEIR ACCESORY ESTRUCTURES. STORAGE ESTRUCTURES. STORAGE ESTRUCTURES RICH IN RESERVE MATERIALS ARE ALSO ABSERVED.