CHANGES IN SPINATION PATTERNS OVER THE COURSE OF METACERCARIAL DEVELOPMENT OF DIPLOSTOMUM PSEUDOSPATHACEUM NIEWIADOMSKA, 1984 (TREMATODA, DIPLOSTOMIDAE).

Metacercarial development of most Diplostomum species including D. pseudospathaceum occurs in the eye lenses of their fish hosts and is accompanied by radical morphological changes often referred to as metamorphosis. One of the structures undergoing substantial changes in D. pseudospathacewn are tegumental spines. The present study used phalloidin staining and confocal microscopy to examine these changes in D. pseudospathaceum over the course of development from 3-day-old to infective metacercariae. Although the general pattern of spination remained essentially unchanged, most larval spines continued growing in size until late in metacercarial development. From day 10 of development, larval spination was gradually replaced by small incipient definitive spines and the infective metacercariae had only definitive spination. The possible adaptive role of spines in developing metacercariae is discussed.