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The microtubule-organizing center (MTOC) is a structure found in eukaryotic
Eukaryote

Animals, plants, fungus, and protists are eukaryotes , organisms whose Cell are organized into complex structures enclosed within Cell membrane....
 cells from which microtubule
Microtubule

Microtubules are one of the components of the cytoskeleton. They have a diameter of 25 Nanometre and length varying from 200 nanometers to 25 micrometers....
s emerge. MTOCs have two main functions: The organization of eukaryotic flagella
Flagellum

A flagellum is a tail-like structure that projects from the cell body of certain prokaryotic and eukaryotic cells, and it functions in locomotion....
 and cilia
Cilium

A cilium is an organelle found in eukaryote cell s. Cilia are tail-like projections extending approximately 5?10 micrometres from the cell body....
 and the organization of the mitotic
Mitosis

Mitosis is the process in which a eukaryotic cell separates the chromosomes in its cell nucleus, into two identical sets in two daughter nuclei....
 and meiotic
Meiosis

In biology or life science, meiosis is a process of reductional division in which the number of chromosomes per cell is halved. In animals, meiosis always results in the formation of gametes, while in other organisms it can give rise to spores....
 spindle apparatus separating the chromosome
Chromosome

A chromosome is an organized structure of DNA and protein that is found in Cell . A chromosome is a single piece of DNA that contains many genes, regulatory sequence and other genetic sequence....
s during cell division
Cell division

Cell division is a process by which a cell , called the parent cell, divides into two or more cells, called daughter cells. Cell division is usually a small segment of a larger cell cycle....
. The MTOC is the site of microtubule nucleation
Microtubule nucleation

Microtubules are filaments of the cytoskeleton. They typically form through the polymerization of a- and ?-tubulin dimers elongating existing microtubules....
 and can be visualized in cells by immunohistochemical
Immunohistochemistry

Immunohistochemistry or IHC refers to the process of localizing proteins in cells of a tissue section exploiting the principle of antibody binding specifically to antigens in biological tissues....
 detection of ?-tubulin
Tubulin

Tubulin is one of several members of a small family of globular proteins. The most common members of the tubulin family are a-tubulin and ?-tubulin, the proteins that make up microtubules....
. In animals, the two most important types of MTOCs are the basal bodies
Basal body

.A basal body is an organelle formed from a centriole, a short cylindrical array of microtubules. It is found at the base of a eukaryotic undulipodium and serves as a nucleation site for the growth of the axoneme microtubules....
 associated with cilia and certain intercellular junctions in epithelial cells, and the centrosome
Centrosome

In cell biology, the centrosome is an organelle that serves as the main microtubule organizing center of the animal cell as well as a regulator of cell-cycle progression....
 associated with spindle formation.

animal cells during interphase
Interphase

Interphase is the phase of the cell cycle in which the cell spends the majority of its time and performs the majority of its purposes including preparation for cell division....
 have one centrosome, usually located near the nucleus
Cell nucleus

In cell biology, the nucleus , also sometimes referred to as the "control center", is a membrane-enclosed organelle found in all eukaryote cell ....
, and generally associated closely with the Golgi apparatus
Golgi apparatus

The Golgi apparatus is an organelle found in most eukaryote Cell . It was identified in 1898 by the Italian physician Camillo Golgi and was named after him....
.






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The microtubule-organizing center (MTOC) is a structure found in eukaryotic
Eukaryote

Animals, plants, fungus, and protists are eukaryotes , organisms whose Cell are organized into complex structures enclosed within Cell membrane....
 cells from which microtubule
Microtubule

Microtubules are one of the components of the cytoskeleton. They have a diameter of 25 Nanometre and length varying from 200 nanometers to 25 micrometers....
s emerge. MTOCs have two main functions: The organization of eukaryotic flagella
Flagellum

A flagellum is a tail-like structure that projects from the cell body of certain prokaryotic and eukaryotic cells, and it functions in locomotion....
 and cilia
Cilium

A cilium is an organelle found in eukaryote cell s. Cilia are tail-like projections extending approximately 5?10 micrometres from the cell body....
 and the organization of the mitotic
Mitosis

Mitosis is the process in which a eukaryotic cell separates the chromosomes in its cell nucleus, into two identical sets in two daughter nuclei....
 and meiotic
Meiosis

In biology or life science, meiosis is a process of reductional division in which the number of chromosomes per cell is halved. In animals, meiosis always results in the formation of gametes, while in other organisms it can give rise to spores....
 spindle apparatus separating the chromosome
Chromosome

A chromosome is an organized structure of DNA and protein that is found in Cell . A chromosome is a single piece of DNA that contains many genes, regulatory sequence and other genetic sequence....
s during cell division
Cell division

Cell division is a process by which a cell , called the parent cell, divides into two or more cells, called daughter cells. Cell division is usually a small segment of a larger cell cycle....
. The MTOC is the site of microtubule nucleation
Microtubule nucleation

Microtubules are filaments of the cytoskeleton. They typically form through the polymerization of a- and ?-tubulin dimers elongating existing microtubules....
 and can be visualized in cells by immunohistochemical
Immunohistochemistry

Immunohistochemistry or IHC refers to the process of localizing proteins in cells of a tissue section exploiting the principle of antibody binding specifically to antigens in biological tissues....
 detection of ?-tubulin
Tubulin

Tubulin is one of several members of a small family of globular proteins. The most common members of the tubulin family are a-tubulin and ?-tubulin, the proteins that make up microtubules....
. In animals, the two most important types of MTOCs are the basal bodies
Basal body

.A basal body is an organelle formed from a centriole, a short cylindrical array of microtubules. It is found at the base of a eukaryotic undulipodium and serves as a nucleation site for the growth of the axoneme microtubules....
 associated with cilia and certain intercellular junctions in epithelial cells, and the centrosome
Centrosome

In cell biology, the centrosome is an organelle that serves as the main microtubule organizing center of the animal cell as well as a regulator of cell-cycle progression....
 associated with spindle formation.

Centrosome

Most animal cells during interphase
Interphase

Interphase is the phase of the cell cycle in which the cell spends the majority of its time and performs the majority of its purposes including preparation for cell division....
 have one centrosome, usually located near the nucleus
Cell nucleus

In cell biology, the nucleus , also sometimes referred to as the "control center", is a membrane-enclosed organelle found in all eukaryote cell ....
, and generally associated closely with the Golgi apparatus
Golgi apparatus

The Golgi apparatus is an organelle found in most eukaryote Cell . It was identified in 1898 by the Italian physician Camillo Golgi and was named after him....
. The centrosome usually has a pair of centriole
Centriole

A centriole is a barrel-shaped organelle found in most animal eukaryotic Cell s, though absent in higher plants and most fungi. The walls of each centriole are usually composed of nine triplets of microtubules ....
s. Microtubules are anchored with their "minus" ends in the centrosome, and because microtubules dissociate preferentially at this end, this anchoring has a stabilizing effect, and MTOC-associated microtubules can grow very quickly. The polarity of the microtubules is important for membrane bound transport, as the motor proteins kinesin
Kinesin

Kinesins are a class of motor proteins found in eukaryotic cells. Kinesins move along microtubule cables powered by the dephosphorylation of Adenosine triphosphate ....
 and dynein
Dynein

Dynein is a motor protein in biological cells which converts the chemical energy contained in Adenosine triphosphate into the mechanical energy of movement....
 typically move preferentially in either the "plus" or "minus" direction, respectively, along a microtubule, allowing vesicles to be directed to or from the endoplasmic reticulum
Endoplasmic reticulum

The endoplasmic reticulum is a eukaryote organelle that forms an interconnected network of tubules, vesicle , and cisternae within cell . The lacey membranes of the endoplasmic reticulum were first seen by Keith R....
 and Golgi apparatus.

Basal body

In epithelial cells, MTOCs also anchor and organize the microtubules that make up cilia. As with the centrosome, these MTOCs stabilize and give direction to the microtubules, in this case to allow unidirectional movement of the cilium itself, rather than vesicles moving along it.

Spindle pole body

In yeast
Yeast

Yeasts are eukaryote microorganisms classified in the Kingdom fungus, with about 1,500 species currently described; they dominate fungal diversity in the oceans....
s and some algae, the MTOC is embedded into the nuclear envelope
Nuclear envelope

The nuclear envelope is a double lipid bilayer that encloses the genetic material in eukaryote cell . The nuclear envelope also serves as the physical barrier, separating the contents of the nucleus from the cytosol ....
 as a spindle pole body. In these organisms, the nuclear envelope does not break down during mitosis and the spindle pole body serves to connect cytoplasmic with nuclear microtubules.

Plant MTOCs

Plant cells lack centrioles or spindle pole bodies. Instead, the nuclear envelope itself appears to function as the main MTOC for microtubule nucleation
Microtubule nucleation

Microtubules are filaments of the cytoskeleton. They typically form through the polymerization of a- and ?-tubulin dimers elongating existing microtubules....
 and spindle organization during plant cell mitosis.

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