[Presence of abundant heterochromatin in the karyotype of Cebus: C. cappucinus and C. nigrivittatus].

The karyotypes of Cebus capucinus and C. nigrivittatus (Primates, Platyrrhini) are compared after applying several banding techniques. The chromosomes have abundant intercallary heterochromatin which can be stained by R-, T- and C-band techniques and which are late replicating. The X chromosome resembles that of man and of numerous primates. However, the late replicating pattern of the X in female lymphocytes resembles that of the late replicating X of human fibroblasts rather than of human lymphocytes. Banding patterns of certain chromosomes appear analogous in Cebus and Cattarhini, including Man.