Defects in male meiosis. (A-C) Meiotic anaphases I in double homozygous tert/nbs1 pollen mother cells, line K12, G2 generation. Bivalents are connected with one (A) or two bridges (B, C). (D) During anaphase II, segregating univalents are interconnected by bridges as a consequence of chromatid fusion in earlier phases of meiosis. Note the coequal pattern of dividing univalents. (E-G) tert mutants, line 69–2, G6. (E) In the majority of anaphase I preparations, no bridges were presented. (F) A bridge detected in anaphase 1 of tert, line 69–2, G6. (G) tert products of anaphase II are morphologically normal univalents (line 69–2, G6). (H-J) Anthers from G6 plants stained with aceto-carmine. (H) nbs1, (I) tert/nbs1, and (J) tert. Bars indicate 10 μm for (A-G) and 200 μm for (H-J).