The distribution and fine structure of the integumentary papillae of the cercaria ofHimasthla secunda(Nicoll)

Abstract

The distribution of the integumentary papillae of the cercaria ofHimasthla secundahas been studied by a variety of techniques. Structures stained by silver nitrate and visible under the light microscope correspond in their spatial distribution with papillae observed under the scanning electron microscope. The tegumentary papillae described with the light and scanning electron microscope are correlated with the specialized nerve endings in the tegument as seen in transmission electron microscopy. The ultrastructure of these papillae is examined by conventional transmission electron microscopy and the probability that these structures are sensory is discussed.