Entamoeba histolytica: Microtubule movement during mitosis

The movement of microtubules (MTs) during nuclear division of Entamoeba histolytica was ultrastructurally studied. Regarding this MT movement, five stages of mitosis could be defined: prophase, metaphase, anaphase A, anaphase B, and telophase. In early stages of mitosis, chromatinic material appeared condensed, and MTs were detected in the center of the nucleus. Later, MTs seemed to grow from an electron-dense body located in the center of the nucleus. This body might be the microtubule organizing center, which organized the MTs, first in a lateral way, and later to form the mitotic spindle, which was made of a bundle of MTs joined by their ends. This junction of MTs to themselves could also be observed in cross-sections. The last stage of mitosis was the nuclear separation. Two different morphological types of intranuclear vesicles were also observed, which seemed to have different types of membrane. Both intranuclear vesicles were present during nuclear division, generally in clusters, and located close to the nuclear periphery.