Loss of chromosome arm cohesion and impaired synapsis during male meiosis in AtCTF7- RNAi. FISH of male meiotic chromosome spreads hybridized with a chromosome 4 arm probe showing chromosomes stained with DAPI (blue) and probe (red). (A-F) Untreated transgenic AtCTF7-RNAi line; (G-L) transgenic AtCTF7-RNAi line treated with dexamethasone. For each set, the left image shows DAPI and the probe merged images, the middle image shows DAPI, and the right image shows the probe alone. (A-C) Early leptotene showing 2 signals. (D-F) Pachytene showing a single probe signal due to complete synapsis of chromosomes. (G-I) Early prophase showing 4 signals, indicating loss of chromatid cohesion. (J-L) Mid-prophase stage showing 3 signals.