Abstract
Nuclear structures similar to those of the nuclear pore complex were found on chromosomes. This finding indicates that part of the pore complex is retained by the chromosomes through mitosis in the absence of the nuclear membrane. The formation of approximately the same number of pore complexes in the presence and absence of protein synthesis during the first 4 h after mitosis proves the reassembly rather than new synthesis of the pore complex. The structure of pore complexes reconstructed in the absence of protein synthesis cannot be distinguished from the structure of those of control cells.