A complex meiotic differentiation program generates genetically diverse haploid cells (gametes or spores) to compensate for the genome doubling that occurs at fertilization. To this end, homologous chromosomes must undergo pairing and recombination before they become partitioned in haploid sets by two consecutive meiotic divisions. Chromosome ends (telomeres) contain a protective complex that is crucial for genomic stability. In meiosis, telomeres become key players in the chromosome pairing process during prophase to the first meiotic division. At the onset of prophase I, telomeres attach to the nuclear envelope, about which they move and transiently cluster in a limited sector of the nuclear periphery. The dynamic clustering of telomeres (bouquet formation) occurs at the onset of the zygotene substage and supports homologue recognition, pairing and telomere DNA metabolism. The following chapter outlines the protocols that have been useful in studies on telomere dynamics and the frequency of earliest prophase I stages in testis suspensions of the mouse, and may be useful to address similar questions in particular mouse mutants that become increasingly available.