Patterns of organization in the fine structure of chromosomes

Abstract

When observations on the chromosomes were limited to light microscopy, the failure of cytologists to reach a consistent formulation of chromosome organization much below the level of the chromatid could be laid largely to insufficient resolution in the microscope and to variations in procedures for preparing the biological material. Attempts to hypothesize a common structural pattern that would account for such divergent modifications as seen in lampbrush, giant polytene and mitotic chromosomes were at best difficult to test unequivocally with the means at hand. Even answers to such questions as whether the anaphase chromosome is split longitudinally once, twice or not at all were in disagreement (1). The lack of solutions to such problems lay directly in the path to an understanding of the structural basis for the genetic organization and function implicit in the gross structure that we know as the chromosome.

Portions of the work discussed in this paper were supported in part by a Special Purposes Grant (INSP-85a and b) from the American Cancer Society, Inc.

Present address: Department of Anatomy, Duke University School of Medicine, Durham, North Carolina.