The process in which tubulin alpha-beta heterodimers begin aggregation to form an oligomeric tubulin structure (a microtubule seed). Microtubule nucleation is the initiating step in the formation of a microtubule in the absence of any existing microtubules ('de novo' microtubule formation).

A process that is carried out at the cellular level which results in the assembly, arrangement of constituent parts, or disassembly of structures formed of microtubules and associated proteins in the cytoplasm of a cell.

Any cellular process that results in the specification, formation or maintenance of a polarized intracellular organization or cell growth patterns that regulate the shape of a cell.

The aggregation, arrangement and bonding together of a set of components to form the spindle that contributes to the process of mitosis.

A microtubule organizing center formed by a band of gamma-tubulin that is recruited to a circumferential band of F-actin at the midpoint of a cell and which nucleates microtubules from the cell division site at the end of mitosis.

A multiprotein complex composed of gamma-tubulin and other non-tubulin proteins. Gamma-tubulin complexes are localized to microtubule organizing centers, and play an important role in the nucleation of microtubules. The number and complexity of non-tubulin proteins associated with these complexes varies between species.

A membrane-bounded organelle of eukaryotic cells in which chromosomes are housed and replicated. In most cells, the nucleus contains all of the cell's chromosomes except the organellar chromosomes, and is the site of RNA synthesis and processing. In some species, or in specialized cell types, RNA metabolism or DNA replication may be absent.

The part of the cytoplasm that does not contain organelles but which does contain other particulate matter, such as protein complexes.

The eventual plane of cell division (also known as cell cleavage or cytokinesis) in a dividing cell. In Eukaryotes, the cleavage apparatus, composed of septin structures and the actomyosin contractile ring, forms along this plane, and the mitotic, or meiotic, spindle is aligned perpendicular to the division plane. In bacteria, the cell division site is generally located at mid-cell and is the site at which the cytoskeletal structure, the Z-ring, assembles.

The microtubule organizing center that forms as part of the mitotic cell cycle; functionally homologous to the animal cell centrosome.

The microtubule organizing center that forms as part of the mitotic cell cycle; functionally homologous to the animal cell centrosome.

Structure adjacent to the plaques of the mitotic spindle pole body.

One of three laminate structures that form the mitotic spindle pole body; the inner plaque is in the nucleus.

The spindle pole body that exists in a cell prior to spindle pole body duplication. An old spindle pole body segregates to the daughter cell upon mitosis, and lacks active proteins involved in signaling exit from mitosis.