Fig. 6. The changes in telomere and CEN number and intranuclear distribution through meiotic interphase and prophase I. (A) Meiotic S-phase; telomeres (red) are clustered around the nucleolus and unpaired; pericentic heterochromatin (green) regions (CENs) are unpaired, extended and dispersed. (B) Meiotic interphase-G2; similar to preceding S-phase except that CENs are condensed. (C) Early leptotene; telomere number variable, between 10 and 20, indicating that telomere pairing is occurring; CENs remain unpaired and widely dispersed. (D) Leptotene; telomeres fully paired (10 signals) and widely dispersed; CENs unpaired and dispersed. (E) Zygotene; telomeres paired and loosely confined to one hemisphere of the nucleus; CEN signal number variable (1-5) due to homologous synapsis and aggregation. (F) Pachytene; telomeres and CENs fully paired and widely dispersed through nucleus.