Spindle fibers attach to a special region on each chromosome called the kinetochore , which is located on the centromere.

Quick Scoop

During cell division (mitosis or meiosis), chromosomes condense and each has a constricted region called the centromere.

  • On top of the centromere sits a protein structure known as the kinetochore.
  • Spindle fibers (which are made of microtubules) latch onto these kinetochores to move chromosomes around the cell.

Once attached, spindle fibers pull sister chromatids or homologous chromosomes toward opposite poles of the cell, ensuring each new daughter cell gets the correct set of chromosomes.

In short, spindle fibers attach to the kinetochore on the centromere so they can grab, line up, and separate chromosomes accurately during cell division.

TL;DR: They attach to the kinetochore region of the centromere on each chromosome.

Information gathered from public forums or data available on the internet and portrayed here.