Differentiation and degeneration of tegumental cells in adult lung flukes, Paragonimus species (trematoda: Troglotrematidae)

Abstract

Fukuda K. 1985. Differentiation and degeneration of tegumental cells in adult lung flukes, Paragonimus species (Trematoda: Troglotrematidae). International Journal for Parasitology 16: 147–156. Ultrastructure of the tegumental cells of the adult lung flukes, Paragonimus ohirai, P. westermani (triploid type), and P. miyazakii, was studied by transmission electron microscopy. The tegumental cells were observed gathered in groups among the parenchymal cells. Each group was composed of several cells showing various stages of differentiation and degeneration. This arrangement was similar among all the Paragonimus species examined. The stages were divided into six phases based mainly on the features of the nuclei and granules in the tegumental cells. Undifferentiated cells (Stage 1) were located at the periphery in the cell group. Differentiation was associated with the successive formation of G1- 4 granules which appeared in the same tegumental cell (Stages 2–5). Degenerating cells (Stage 6) contained all types of granules and condensed nuclei with crystalline structures. In the cytoplasm of the differentiating cells were also observed lysosome-like structures, crystalline inclusions, and chromatoid body-like structures.