Origin, structure and function of subcuticular cells of Fasciola hepatica.

In the present paper the ultrastructure of the subcuticulare zone of the tegument of Fasciola hepatica and the distribution of thimidine-H3 for establishing the localization of DNA-synthesis in the tegument was studied. There were two types of subcuticular cells: 1) non-differentiated cells with presence of incorporated labelled thimidine in nuclei presented by DNA non-stable macromolecules, and 2) differentiated or definitive subcuticular cells without aggregates of silver grains. The results showed a high level of DNA replication leading to mitotic activity of the non-differentiated cells and absence of mitotic activity in the definitive cells. There was a morphological similarity between non-differentiated cells and the cells from the medular zone, supposing a relationship in their origin.