Fig. 5. Scoring meiotic pairing and bouquet arrangement by FISH. (A-J) Two loci, one close (region B) and one at a larger distance (region A) from the telomeric end of the MIC (arrowheads), which is tapered and DAPI-pale (see Loidl and Scherthan, 2004), were delineated by FISH. Separate FISH signals (A-C,F-H) are scored as indicating the absence of pairing. Single FISH signals (D,E,J) and double dots (I) reflect pairing of the corresponding homologous loci. Examples are shown from wild type (A-F), the hop2A mutant (G,I) and the spo11 mutant (H,J). (K-N) FISH with a compound telomere probe (orange) suggests that (some) telomeres are assembled near one end of stage-II MICs of the wild type (K) and the spo11 mutant (M). In the wild type, the telomere signal becomes very strong upon further elongation of the MIC (L), whereas in the spo11 mutant, only weak scattered signals remain visible, presumably indicating dispersal of the telomeres in stage-III-like MICs (N). The elongated MICs shown are relatively straight because the Carnoy fixation procedure releases nuclei from the cells, which improves FISH. Scale bar: 5 µm.