Interphase chromosome arrangement in Sertoli cells of adult mice

Sertoli cells of adult male laboratory mice were examined with a number of banding techniques and by nonradioactive in situ hybridization applying different repetitive DNA probes. All banding methods revealed the typical features of mouse Sertoli cells, i.e., a central nucleolus, usually with two chromocenters associated at diametrically opposed sides in which the centromeric regions of the chromosomes are clustered. Silver staining as well as in situ hydridization with rDNA labeled part of the chromocenters and the nucleolus, indicating transcriptional activity of at least some of the nucleolus organizer regions. In situ hybridization with X- and Y-specific DNA probes showed both sex chromosomes to be undercondensed in Sertoli cells This decondensation suggests expression of sex chromosomal genes in Sertoli cells. While the X chromosome appeared to occupy a central position near one of the chromocenters, the Y chromosome was found at the periphery of the nucleus in the majority of cells. Hybridization with telomeric sequences resulted in strong labeling of the chromocenters and dispersed signals at the nuclear periphery.