What is symmetric spindle and asymmetric spindle?

asymmetric divisions. In polarized cells, orientation of the spindle perpendicular to the polarity axis causes a symmetric (proliferative) division (A). However, spindle orientation parallel to the polarity axis results in an asymmetric (differentiative) division (B).

Where are the spindles in mitosis?

Mitotic spindle scaling. At metaphase during symmetrical cell division, the spindle must be located at the centre of the cell, the chromosomes placed on the spindle equator and the spindle poles positioned a specific distance apart.

Is there spindle formation in mitosis?

During mitosis, the spindle fibers are called the mitotic spindle. Long protein fibers called microtubules extend from the centrioles in all possible directions, forming what is called a spindle. Some of the microtubules attach the poles to the chromosomes by connecting to protein complexes called kinetochores.

What is the rule of spindle fibers in mitosis?

Kinetochore fibers and spindle polar fibers work together to separate chromosomes during mitosis and meiosis. Spindle fibers that don’t contact chromosomes during cell division extend from one cell pole to the other. These fibers overlap and push cell poles away from one another in preparation for cytokinesis.

How is the mitotic spindle used in asymmetric division?

The classical view of asymmetric division posits that upstream cortical cues are used to coordinate the polarized distribution of cell fate determinants and the orientation of the mitotic spindle. The control of cell fate determinant localization has been recently reviewed elsewhere ( Knoblich, 2010) and will not be treated here.

How does the orientation of the mitotic spindle affect cell fate?

The orientation of the mitotic spindle has been proposed to control cell fate choices, tissue architecture, and tissue morphogenesis. Here, we review the mechanisms regulating the orientation of the axis of division and cell fate choices in classical models of asymmetric cell division.

Where is the spindle located in a dividing cell?

In a symmetrically dividing cell, the spindle is located at the center of the cell through mechanisms that may passively position it [4].

What is the role of Numa in the mitotic spindle?

Like in invertebrates, NuMA is likely to regulate mitotic spindle orientation via the Dynein-Dynactin complex, whose components Lis1 and Huntingtin (Htt) were shown to control the planar orientation of the mitotic spindle of mouse neuroepithelial progenitors (Yingling et al., 2008, Godin et al., 2010).

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