The Bouquet

Abstract

The bouquet, i.e., polarisation of chromosome ends to a restricted area of the nuclear membrane opposite to centrosome and fusomal mouth, is a standard event in meiosis of most Eukaryota. In mitosis, attachment of all chromosomes to nuclear membrane by nuclear pore complexes is maintained until the membrane breaks down: the bouquet cannot and needs not be formed. Intimate pairing of homologues by synaptinemal complexes requires detachment of chromosomes from the nuclear membrane in meiotic prophase. To compensate the loss of multiple communication with cytoplasm through nuclear pores, the telomeric pore complexes become associated directly with the extranuclear activity center, the idiosome (= centrosome surrounded by spindle precursor, mitochondria, and Golgi apparatus). Bouquet-less meiosis is probable where homologues are so close together at the nuclear membrane that they can pair intimately without being detached from the membrane. Bouquet is comparable with Prokaryote and "Mesokaryote" systems, in which chromosomes are permanently attached to cellular or nuclear envelope and/or to centrosome equivalents for the purpose of replication, function, and segregation.