Figure 1

Bouquet configuration in early meiotic prophase nuclei of 2n = 40 and 2n = 24 spermatocytes. Diagram (a) and nucleus (a') showing the configuration of autosomal chromosomes in the “bouquet” of a 2n = 40 spermatocytes. The chromatin of the sex bivalent is also represented (a). The centromeres (red) aggregate in one main group at the nuclear periphery, while the chromosomal axes (green) describe arches toward the nuclear space. Diagram (b) and nucleus (b') showing the configuration of autosomal chromosomes in the “bouquet” of a 2n = 24 spermatocyte. The chromatin of the sex bivalent is also represented (b). The centromeres appear in two major clusters: one at the nuclear periphery, grouping the centromeres of the telocentric bivalents, and the other toward the nucleus center, grouping the centromeres of the metacentric Rb bivalents. The axes that emerge from the peripheral centromeres are shorter than those linked to the central centromeres. The chromosomal axes (green) and centromeres (red) in nuclei with preserved sphericity from 2n = 40 and 2n = 24 spermatocytes were identified by immunochemistry using, respectively, anti-SYCP3 and anti-CENPA antibodies. Bar = 5 μm.