RESUMEN
The chromosome complement of four species phylogenetically related to man, the chimpanzee (Pan troglodytes), the pygmy chimpanzee (Pan paniscus), the gorilla (Gorilla gorilla), and the orangutan (Pongo pygmaeus) have been analysed with chromosome banding techiniques and compared to the human chomosome complement. This has shown remarkable homologies between species, and presumed mechanism of chromosome evolution have been proposed. Chromosome heteromorphism in the great apes have been compared to those found in human populations, and most o them affected the distribution or the amount of constitutive heterochromatin and/or brilliantly fluorescent material, a situation comparable to man where such variation have been established as chromossome polymorphisms. However, a balanced polymorphic structural rearregement involving large segments of euchromatic material has been found in two populations of orangutan. This rearrangement consisted of two pericentric inversions, one inside the other, comprising an unusual kind of chromosome polymorphism in mammalian populations. Moreover, it showed that pericentric inversions, the most probable chromosome rearrangements in the phylogeny of the chromosome of man and the great apes, might not necessarialy be restricted by infertility barriers, but may spread successfully in the popluation. The patterns of late replication of the chromossome of the great apes and man have been compared, using BUrd as a thymidine substitute in the cell cycle. This has show remarkable similarities in the patters of the pattehumam of late replication between species, and, as in the human chromosome, most regions of late replication in the chromosome of the great apes corresponded to areas of positive G-banding...