Naegleria fowleri: Light and electron microscopy study of mitosis

DAPI and Feulgen stains were used as specific DNA markers for studying the mitosis process in Naegleria fowleri. Both DAPI and Feulgen stains reacted with DNA in the nuclei of the amoebae. Representative fig- ures of N. fowleri mitotic nuclei with a defined arrangement according to the phase of the cell cycle were observed. A notable characteristic is that the nucleolus is present throughout the stages of mitosis. During metaphase, several deeply stained DNA condensations following an elongated pattern were observed, corresponding almost certainly to tightly grouped chromosomes. Ultrastructural observations demon- strated that the nucleus divides by cryptomitosis, a process in which the nuclear membrane does not dis- appear during the mitosis. Centrioles were not found, and a spindle of microtubules was observed running the length of the nucleus from pole to pole however, they did not come to a focal point.