Chromatin-free compartments and their contents in anaphase chromosomes of higher plants

Abstract

Chromatin-free compartments and their contents were observed in chromosomes of root tip meristematic cells of Vicia faba and Allium cepa . The central chromatin-free compartment of chromosome was usually larger than the peripheral ones. In tranverse section, every chromosome showed peripheral chromatin-free compartments though their number and size varied. In longitudinal section, the central chro matin-free compartments were found to be distributed intermittently along the chromosomal axis. The contents, which showed a granular-fibrillar nature and linked up to the rest of the chromosome, were seen in the central and at least some of the peripheral chromatin-free compartments. A cytochemical study revealed that these contents consisted of ribonucleoprotein granules and fibrils. The contents are a special constituent of the chromosome. The chro matin-free compartments in a chromosome seemed connected with one another and their contents may form a network system which plays a role in the maintenance and stabilization of the higher-order structure of chromosome.