Trypanosoma cruzi has been examined with the electron microscope. Crithidia and metacyclic forms of a blood agar culture have been studied and compared with the adult tissue forms, obtained in tissue cultures, from the same strain.
In all the forms studied, the internal structure of the body is not revealed because it is too thick for electron penetration. In places where a good penetration has been obtained the cytoplasm shows a fine striation in spiral or parallel arrangement. This striation can be digested with trypsin or by prolonged osmic acid fixation.
Dense spherical bodies of variable size can also be observed in the body portion. They can be dissolved with xylene.
The whole body of the trypanosome is covered by a fine, transparent sheath.
The flagellum is formed by the axoneme which consists of five or nine fibres. It can be followed throughout the whole length of the metacyclic and of the adult tissue forms. In the crithidia forms of the blood-agar culture, it disappears in the anterior part of the body. The whole flagellum is covered by a fine sheath. The axial fibre bundle can be digested with trypsin or by prolonged osmic-acid fixation. Both, the striation and the fibre bundle are contractile structures which could explain the movements of the trypanosome.
Some dividing forms are also described.