The secrecy of the nature of the centromere-kinetochore complex of mam
mals is beginning to be betrayed. One can already firmly suggest that,
among the other satellite DNAs which are a subset of the constituants
of the human centromeric regions, the alpha satellite is probably con
tributing to the function of the centromere. The physical structure of
the centromere-kinetochore complex is variable from one chromosome to
the other and, moreover, prone to extreme polymorphism. Interactions
between DNA and some of the proteins of the complex have been demonstr
ated. One still does not know, however, why centromeric regions remain
compact all along the cell cycle, why they are restricted in recombin
ation and if they contain any gene. Centromere dysfunction is associat
ed with a number of pathologies in man (aneuploidies, cancers...). A n
umber of important questions concerning their structure and function r
emain, however, unanswered.