Demonstration of the spiral structure of human chromosomes.

Abstract

CHROMOSOMES have generally been regarded as consisting of coiled chromonemata. Although a number of cytological observations on the structure of chromosomes in plant germ cells have been conducted, as well as many studies on the fine structure of animal chromosomes at the molecular level, structural relations of chromonema and its molecular components are still poorly defined1,2. Since the Denver Conference of Human Chromosomes Study Group, a number of morphological investigations have been carried out on the identification of each chromosome to establish the standard normal human karyotype, particularly with respect to the sites and relative frequencies of secondary constrictions3–5. There is general agreement regarding the normal karyotype; however, little or no morphological evidence has been presented to confirm the spiral structure of human somatic chromosomes. As an innovation to the technique for chromosome preparation, the following method has been developed which clearly demonstrates somatic coils through the partial dissociation of human chromosomes.