Aster (cell biology)

An aster is a cellular structure shaped like a star, consisting of a centrosome and its associated microtubules during the early stages of mitosis in an animal cell.

During mitosis, there are five stages of cell division: Prophase, Prometaphase, Metaphase, Anaphase, and Telophase.

During prophase, two aster-covered centrosomes migrate to opposite sides of the nucleus in preparation of mitotic spindle formation.

During metaphase, the kinetochore microtubules extending from each centrosome connect to the centromeres of the chromosomes.

[3] Astral microtubules develop in the actin skeleton and interact with the cell cortex to aid in spindle orientation.

At the negative ends of the aster centrosomes will nucleate (form a nucleus) and anchor to the microtubules.

This diagram depicts the organization of a typical mitotic spindle found in animal cells. Chromosomes are attached to kinetochore microtubules via a multiprotein complex called the kinetochore . Polar microtubules interdigitate at the spindle midzone and push the spindle poles apart via motor proteins. Astral microtubules anchor the spindle poles to the cell membrane. Microtubule polymerization is nucleated at the microtubule organizing center .