[The parenchymal cellular composition and extracellular matrix in ontogenesis of Triaenophorus nodulus (Cestoda)].

The cellular composition of parenchyma was studied in the ontogenesis of Triaenophorus nodulosus and it was shown that the specialized parenchymal cells was absent. The extracellular matrix fibrils were synthesized successively by the tegumental cytons and muscle cells. The coracidium basal matrix consisted of electron-light and electron-dense layers, and the reticular layer appeared at the procercoid stage. Reserve nutrients were accumulated by the musculocutaneous sac elements at the procercoid stage and, later, by the glandular and tegumental cells. It has been proposed that the parenchyma as an independent histological unit is absent, while the parenchymal organization is based on all specialized cellular elements that do not lose their typical features.