Transmission electron microscopic studies on the tegument of mature proglottid of Proteocephalus pentastoma infesting Mormyrus kannume revealed the presence of two types of microtriches (filiform and spiniform) and a delicate glycocalyx screening the tegument exteriorly. The syntegument rets were monitored internally on a thin basal lamina and contained light membrane-bounded vesicles, dim bodies with no bordering membrane, electron-dense granules, large excretory vesicles, and few ovoid mitochondria that were more concentrated near the basal lamina. A delicate fibrous layer was detected confirming the syntegument with the underlying cytotegument. Networks of poorly developed muscular bundles were found down the distal cytoplasm containing circular, longitudinal, diagonal, and deep patches of ventral muscle bundles, respectively. In the current study, fine structures of various cytotegumental cells and the syncytial structures of the osmoregulatory ducts were described in detail.