Fig. 5. Confocal imaging of meiotic chromosomes and spindles from B6 and Rb/+ spermatocytes (ß-tubulin in red, phospho-histone H3 in green). (A) A MI spermatocyte from a control B6 mouse in which all chromosomes are found to be properly aligned on the metaphase plate. (B) A MI spermatocyte from a Rb/+ mouse, illustrating unaligned chromosomes (arrowheads). (C) A MI spermatocyte from a Rb/+ mouse displaying a misaligned chromosome (arrowhead) and an abnormal spindle, in which one pole is undeveloped (arrow). (D) Rb/+ MII spermatocytes depicting chromosomes lagging behind the spindle poles (arrowheads). Scale bar: 10 µm.