Ultrastructure of sensory endings in Diplostomum pseudospathaceum Niewiadomska, 1984 cercariae (Digenea, Diplostomidae).

Using TEM techniques, 13 types of sensory endings were revealed on the body and tail of cercariae of D. pseudospathaceum. They differ in the presence or absences of cilia, number of cilia, number of electron-dense rings, basal body type and collar shape. The following groups of sensory endings were distinguished: uniciliate with a short (5 types), moderately long (one type) or long cilium (4 types); multiciliate sensory pits (2 types); and nonciliate sensory bulbs. Most sensory endings with long cilium and nonciliate sensory bulbs were found on the tail stem. All the breviciliate sensory endings and multiciliate sensory tips, as well as 1 type with long cilium, were situated on the cercarial body. The uniciliate sensory endings with a moderately long cilium were found on the furcae. The ultrastructural variety of sensory endings in different groups of Digenea, as well as their supposed functions, are discussed.