text: In animal cells The kinetochore is composed of several layers, observed initially by conventional fixation and staining methods of electron microscopy, (reviewed by C. Rieder in 1982) and more recently by rapid freezing and substitution.
  The deepest layer in the kinetochore is the inner plate, which is organized on a chromatin structure containing nucleosomes presenting a specialized histone (named CENP-A, which substitutes histone H3 in this region), auxiliary proteins, and DNA. DNA organization in the centromere (satellite DNA) is one of the least understood aspects of vertebrate kinetochores. The inner plate appears like a discrete heterochromatin domain throughout the cell cycle.
  External to the inner plate is the outer plate, which is composed mostly of proteins. This structure is assembled on the surface of the chromosomes only after the nuclear envelope breaks down. The outer plate in vertebrate kinetochores contains about 20 anchoring sites for MTs (+) ends (named kMTs, after kinetochore MTs), whereas a kinetochore's outer plate in yeast (Saccharomyces cerevisiae) contains only one anchoring site.
  The outermost domain in the kinetochore forms a fibrous corona, which can be visualized by conventional microscopy, yet only in the absence of MTs. This corona is formed by a dynamic network of resident and temporary proteins implicated in the spindle checkpoint, in microtubule anchoring, and in the regulation of chromosome behavior.