This chapter describes a technique for performing chromosome spreads from mouse oocytes. It is based on a previously described protocol (Hodges and Hunt, Chromosoma 111: 165–169, 2002), which we have modified. Chromosomes are stained with either Propidium Iodide or Hoechst. This spreading technique allows for simultaneous immunostaining of proteins associated with chromosomes. It is very useful to stain spreads with CREST serum which labels kinetochores, to be able to distinguish bivalents (chromosome pairs), dyads or univalents (paired sister chromatids), and single sister chromatids without ambiguity.
