Precise Determination of Centromere Locations

Abstract

A system of chromosome classification based on arm ratio has been proposed to enable the cytologists to determine precisely and describe accurately all the known centromere locations. Median (M), submedian (SM), subterminal (ST) and terminal (T) have been considered as fixed point positions while, nearly median (nm), nearly submedian (nsm), nearly subterminal (nst) and nearly terminal (nt) are the four intermediate regions of these four fixed point positions. A table embodying nomenclature, notation, centromere location and the arm ratio values-R₁ as short arm/long arm and R₂ as long arm/short arm has been represented to serve as a ready reckoner for chromosome classification. The advantage of the present system has been discussed in the light of other systems which were erected arbitrarily for specific materials to meet specific needs.