Chromosome Segregation During Meiosis: Building an Unambivalent Bivalent

摘要: Faithful chromosome segregation during anaphase requires that stable microtubule connections are established between chromosomes and both spindle poles by metaphase. Bipolar orientation follows an active period of transient the kinetochores poles, tension mediated through attachments stabilizes those bivalents have to opposite poles. This review focuses on how chromatids tied together in bivalent ensure proper two meiotic divisions. Homologs partitioned meiosis I, reciprocal crossovers, cytologically defined as chiasmata, usually hold homologs for this division. The crossovers themselves must be prevented from migrating off chromatid arms. Binding substances localized crossover sister-chromatid cohesion distal been proposed prevent loss chiasmata. Spontaneous nondisjunction events mutations disrupt maintenance chiasmata analyzed context these models. segregate I without briefly discussed. also constructed so four present only functional prior I. Cytology genetic data suggest sister duplicated but constrained act a single kinetochore. Additionally, centromeric regions preserve their until II, even arms is lost at Mutations specifically process presented.