Fine‐Structural Changes Associated with Pseudocyst Formation in <i>Trichomitus batrachorum</i>*

Abstract

SYNOPSIS. Several fine‐structural changes were observed during formation of the so‐called pseudocysts of Trichomitus batrachorum grown in an agar‐free medium. Among these changes the most frequent were those of the undulating membrane complex. Internalization of the marginal lamella combined with disappearance of the fin‐like, membranous dorsal fold occurred with the highest frequency. In many organisms these alterations were accompanied by internalization of the recurrent flagellum, which, however, remained external in other, presumably earlier stages of pseudocyst formation. In some of the internalized and even still external recurrent flagella the microtubules were in various states of disassembly. The often distended flagellar membrane enclosed large accumulations of filaments 5 nm in diameter. Internalization of the anterior flagella also was noted. Changes similar to those characteristic of the recurrent flagella were not seen, however, among the microtubules of the anterior flagella or among those of the pelta or the axostyle.