The Ultrastructure of Tritrichomonas with Special Reference to the Blepharoplast Complex*

Electron micrographs of sections through the blepharoplast complex reveal it to be composed of four kineto‐somes. In many of the sections the kinetosomes contain dense particles approximately 180‐200 A in diameter. The costa is a striated fiber which extends posteriorly almost the entire length of the body. Its slender proximal portion appears to be attached to the base of the kinetosome of the recurrent flagellum. The parabolas fiber is similarly constructed, but is more slender than the costa. It is attached to the base of the kinetosome of an interiorly directed flagellum and subsequently proceeds posteriorly to the level of the nucleus. The costa and parabasal fiber probably serve as anchoring or supportive structures. The size of the costa may reflect its role as a supporting structure for the most highly differentiated locomotors organelle, the undulating membrane.