acase@tulane.edu

Through the use of a large plerocercus-type, trypanorhynch bladderworm, it was possible to monitor the assimilation, storage and utilization of carbohydrates within a metacestode bladder and its inlying, metacestode scolex. The plerocercus used in this study was tentatively identified as Otobothrium insigne (Linton, 1905). Trypanorhynch plerocerci typically consist of a juvenile scolex surrounded by a bladder-like blastocyst. The overall morphology of the O. insigne plerocercus differs from the other histologically described plerocerci only in the presence of a large, fluid-filled cavity within its blastocyst. Thus, the blastocyst consists of a thick, outer blastocyst wall that is separated from a thin, inner wall by the blastocyst cavity. The abscolex end of the juvenile scolex is loosely attached to the inner wall; the remainder of the scolex lies within a second, smaller cavity created by the inner wall. The outer and inner blastocyst walls, and the juvenile scolex are each composed of the various somatic, cytological components characteristic to all post-oncospheric cestode developmental stages. Large quantities of carbohydrates are located within the various plerocercus compartments. In the blastocyst walls and juvenile scolex, the carbohydrate reserve exists primarily as glycogen. The blastocyst cavity contains only a small amount of glycogen; instead this compartment stores large quantities of free glucose, at concentrations up to 200 times that of the host serum. Glucose transport studies demonstrated the capacity of the outer blastocyst wall to effectively concentrate glucose within the blastocyst and thus 'push' glucose into the juvenile scolex above the scolex's own transport capabilities. During times of in vitro fasting, the juvenile scolex takes nutritional precedence over the blastocyst, such that glycogen levels in the blastocyst are sacrificed to maintain carbohydrate steady state conditions in the juvenile scolex / acase@tulane.edu

acase@tulane.edu

acase@tulane.edu

acase@tulane.edu

acase@tulane.edu

acase@tulane.edu

acase@tulane.edu

acase@tulane.edu

acase@tulane.edu