Fig. 6. Proposed structural rearrangements of the microtubule networks during gametocyte development.

In stage I, the centriolar plaque, which spans the inner and outer nuclear membranes, initiates the formation of nuclear microtubules. The associated kinetochores capture the centromeres of the chromosomes. In stage II, sub-pellicular microtubules appear to be nucleated from the outer centriolar plaque, and the inner membrane complex (IMC) is initiated from an extension of the nuclear envelope/endoplasmic reticulum (ER) at a site close to the centriolar plaque. As the gametocyte develops, both the intranuclear and subpellicular microtubules extend - elongating the nucleus and the whole cell. In stage III, the sub-pellicular microtubules disconnect from the centriolar plaque/ microtubule organizing centre (MTOC) and are stabilised by association with the IMC. In stage III, the kinetochores translate along the nuclear microtubules, thus reorganising the chromatin – an event that may play a role in transcriptional control. In stage IV, the nuclear microtubules are depolymerised to remnant stubs; and the chromatin contracts back towards the centriolar plaque; while remodelling of the subpellicular microtubules is signalled by polyglutamylation (polyE). In stage V gametocytes, the sub-pellicular microtubules are also depolymerised.