Abstract
The C-banding karyotype of Hepatica nobilis indicates the A chromosome complement and B chromosomes (Bs) to be banded in the terminal regions. The A chromosomes (As) of this species comprise mainly euchromatin (89.7%) and a small amount of heterochromatin (10.3%). Bs of H. nobilis have terminal centromeres at one end and possess small satellites at the other end. Bs cause an increase in the number of nucleoli per cell, with a decrease in the size of each nucleolus. During meiosis, Bs associate as bivalents and multivalents up to pentavalents. These associate loosely with the short arm of satellited chromosome 7 (end to end association) at diakinesis in some pollen mother cells. Bivalent or trivalent Bs associate with a nucleolus at diakinesis. B chromosomes of H. nobilis thus appear to contain nucleolus organizing regions and may have originated from the satellited chromosome 7 and other members of As.Key words: Hepatica, satellited B, end to end association, origin, nucleolus organizing regions.