Comparison of P. ridibundus (a, b, c, d, d`) and P. lessonae (e, f) lampbrush chromosome B. Phase contrast micrographs (b, e), immunofluorescent staining with antibodies against coilin (a), TMG-cap of snRNAs (c, f). Sites with mapped (TTAGGG)n repeat (d) are indicated by arrows. Spheres (shown by arrows) in subtelomeric region of the long arm of P. ridibundus lampbrush chromosome B (a, b, c). Long marker loops (shown by arrows) (e, f) close to sphere loci in the long arm of P. lessonae lampbrush chromosome B. Chromosomes are counterstained with DAPI. Nu – extrachromosomal nucleoli. Arrowheads show centromeres. Scale bars = 50 μm. Asterisks indicate enlarged fragment of lampbrush chromosome B with mapped (TTAGGG)n repeat (d`). Arrows indicates telomeric and interstitial blocks of sequences containing (TTAGGG)n repeat in a subtelomeric region of the long arm of P. ridibundus lampbrush chromosome B (d'). Scale bars = 10 μm.