Arrangement of chromosome ends and axial core formation during early meiotic prophase in the male grasshopper Brachystola magna by 3D, E.M. reconstruction.

Evidence is presented that chromosome ends are attached to the nuclear envelope prior to the formation of axial cores during early meiotic prophase in the grasshopper Brachystola magna. The attachment sites of distal and proximal chromosome ends are clustered in a small region of the inner nuclear envelope resulting in a classical bouquet arrangement of the chromosomes. Proximal ends are tightly clustered due to the presence of chromocenters. Distal chromosome ends are more widely scattered throughout the base of the bouquet.--Axial core formation can be initiated at chromosome ends or at internal chromosome sites. However, there is a preference for axial cores to form in distal chromosome regions rather than proximal regions during early meiotic prophase.--Virtually all of the nuclear pore complexes are located in the general vicinity of the chromosome attachment sites but each specific attachment site is surrounded by a small area of nuclear envelope which is devoid of pore complexes.