Figure 1

Examples of FISH with both 18S rDNA (green) and telomeric DNA (red) probes in spermatogonial metaphase (a, c, d, g, h) or diakinesis (b, e, f), as well as karyotypes arranged from these divisions (a’–h’) and silver staining in diakinesis (i–k) and diplotene (l) of chromosomes for the following Poecilimon species: P. cervus (a, a’), P. bosphoricus (b, b’, i), P. chopardi (c, c’, j), P. klisuriensis (d, d’), P. macedonicus (e, e’, k), P. ukrainicus/fussii (f, f’), P. affinis (g, g’), and P. zwicki (h, h’, l). White arrowheads point to rDNA clusters near the centromeric or distal regions of the chromosomes. Hybridization areas vary in size between some homologous chromosomes, which are marked with an asterisk (*). Black arrowheads indicate the presence of one (i), two (j, k), or four (l) active NORs. 18S rDNA signals in mitotic metaphase/diakinesis coincide with NORs. Bar = 10 μm.