Brush‐like fibers on the human chromosome periphery

A brush-like border apparently composed of fibers protruding from metaphase chromosomes of human lymphocytes was observed for the first time using transmission (TEM) and scanning electron microscopy (SEM). On the basis of size and sensitivity to colcemid, the fibers may be related to microtubules and spindle organization. The brush-like fibers were observed when chemically fixed metaphase chromosome spreads were placed on glass slides and maintained under “wet” conditions (not allowed to air dry after fixation for conventional cytogenetic protocols) until postfixation protocols for TEM and SEM were performed. The purpose of this study was to establish the occurrence of the brush-like fibers and to determine the effects of colcemid on these fibers.