NUCLEI, DIVISION AND MITOSIS

Euglenids and kinetoplastids have a single nucleus. The chromosomes appear condensed even in interphase, with the nucleus having a granular appearance at all times. There is often a large nucleolus. This can be seen in the transmission electron micrograph below.

 DIVISION

When euglenids divide, the flagella replicate first, and a division furrow passes from the front of the cell to the back.

MITOSIS

The nucleus divides by mitosis. The microtubular spindle (sp) which is used to separate the duplicated chromosomes from each other, and to push the poles of the dividing nucleus apart, develops inside the nucleus. The spindle is evident in the micrograph below. Nu= nucleolus.

Sexuality

There are no confident descriptions of sexuality in euglenids. There is some evidence of allelic resorting in kinetoplastids, and this is indirect evidence of some form of sexuality.