Abstract: | The fine structure of the dividing nucleus in the intracellular amastigote forms of Trypanosoma cruzi from tissue cultures has been described. In the first phase of division the nucleus shows a homogenous structure owing to the dispersion of its chromatin and nucleolar material. Microtubules similar to those of a mitotic spindle in metozoan cells then appear, running from one pole to the other. They disappear when the division of the nucleus is complete and the chromatin and the nucleolar material reorganize into their former positions. |