title: Intercalar satellites of human acrocentric chromosomes as a cytological manifestation of polymorphism in GC-rich material?
abstract: Fifteen unrelated individuals were found among the patients of the Cytogenetics Laboratory who possessed multiple-satellited marker chromosomes (14 with double satellites and 1 with triple satellites). Cytogenetic analysis was carried out by means of a conventional staining method and also by R, C, and Q banding and by the technique of silver staining. The intercalar structures of all 15 cases differed from the terminal satellites in their biochemical composition: they were resistant to heat denaturation, and stained heavily with the R-banding technique. Accordingly, they consisted of GC-rich material identical with that which in varying quantity is a regular constituent of the short arms of acrocentric chromosomes. The findings described indicate that any larger accumulation of such R band-positive material tends to dissociate from the basal segment of short arms by a proximal secondary constriction. We therefore assume that the formation of intercalar satellites may be interpreted as a cytological consequence of extreme natural R polymorphism.
mesh_terms: D000328:Adult; D001482:Base Composition; D002648:Child; D002869:Chromosome Aberrations; D002871:Chromosome Banding; D002901:Chromosomes, Human, 13-15; D002904:Chromosomes, Human, 21-22 and Y; D005260:Female; D005819:Genetic Markers; D006801:Humans; D007621:Karyotyping; D008297:Male; D009697:Nucleolus Organizer Region; D012835:Silver Nitrate; D013194:Staining and Labeling
chemical_list: D005819:Genetic Markers; D012835:Silver Nitrate