Question

How many types of spindle fibres are formed during cell division in eukaryotes?
A. 3
B. 4
C. 5
D. 2

Answer 1

During the process of cell division, the microtubule cytoplasmic tissue disappears and the microtubules are reassembled in the form of a spindle in the dividing cell (both in mitotic and meiotic cell division).

Complete answer:
There are mainly three types of spindle fibers formed in eukaryotic cell these are
1.Astral microtubule: These microtubules develop in the actin structure and interact with the cell cortex to guide the spindle, positioning them radially around the centrosome. The circulation rate of this population of microtubules is higher than that of other populations.
The role of the astral microtubules is supported by certain dynamics. In this din, the light chain (static part) is attached to the cell membrane, and the spherical part (dynamic part) is attached to the microtubules. The globular chain tries to move towards the centrosome, but because it is associated with the cell membrane, the centrosome retreats towards the membrane, helping to divide the cytoplasm.
The role of astral microtubules in mitosis is to ensure the correct position and orientation of the mitotic spindle device in accordance with the polarity of the cell. Although this feature is important for mitosis, this process does not require the strict advancement of the astral microtubules.
2.Polar microtubule: These microtubules interdigitate at the spindle middle zone and push the spindle pole apart through the motor proteins.
3.Kinetochore microtubule: The kinetochore microtubules bind directly to the kinetochore. Each chromosome has two chromatids and each chromatid has a kinetochore. The two kinetochores are linked by a region on the chromosome called the centromere.

So, from the above made discussion, we can say option A is correct.

Note: Astral microtubules are not required for mitosis, but for the accuracy of the process. The function of the astral microtubules can usually be seen as the defining cell geometry. They are essential for the correct positioning proteins and alignment of the mitotic spindle and thus help determine the location of cell division based on cell structure and polarity.
The integration of astral microtubules depends on the maintenance of astral microtubules. It also depends on several microtubule-associates such as EB1 and adenomatous polyp (APC).