Constricted region of a chromosome that joins the two chromatids to each other and attaches to spindle fibers in mitosis and meiosis.
Source:
PAC, 2016, 88, 713. 'Glossary of terms used in developmental and reproductive toxicology (IUPAC Recommendations 2016)' on page 734 (https://doi.org/10.1515/pac-2015-1202)