Electron microscopic study of Trypanosoma cruzi periplast in tissue cultures. I. Number and arrangement of the peripheral microtubules in the various forms of the parasite's life cycle.

In an electron microscopic study, counts of peripheral microtubules were made in spheromastigotes and trypomastigotes in tissue cultures of embryonic heart muscle cells. In interphase spheromastigotes there were, at the level of the nucleus, approximately 114 microtubules; in dividing forms, there were approximately 222. In trypomastigotes, the number of microtubules varied according to the level of the section--there were fewer than 40 tubules in the pointed ends of an organism, while in the central segment the number of these elements ranged from 60 to 115. The highest number of microtubules was found in the region containing the Golgi complex. The distance between the microtubules was constant, equalling 44 nm, even at the pointed ends of a trypanosome. This suggests that the microtubules course parallel to one another. Cross sections and randomly arranged, variable length, longitudinal sections of the tubules were noted around the kinetosomes in dividing organisms.