The dark-stained structures in the chromosomes best recognized during pachytene stage, representing local condensation of the chromatin (see Fig. C91). Dark knobs are a characteristic feature of certain genomes within a species. The presence of knobs may affect recombination frequencies in their vicinity and knobs may be involved in preferential segregation. chromosome morphology, knob, karyotype, pachytene analysis, preferential segregation; Ananiev EV et al 1998 Genetics 149:2025.
