Nuclear pole complexes in cells of developing mouse cerebral cortex

The nuclear pore complexes of cells of the superficial layers of the cerebral cortex of mice were studied by freezeetch technique from the 18--20th embryonic to 180th postnatal day. The nuclear membrane was found to be randomly penetrated by pore complexes in all age groups studied. The pores have a typical octagonal shape. The density of pores (per/um2) amounted to 7.8, 14.0, 17.0, 18.1 and 14.1 on 18--20th embryonic and 8th, 15th, 50th and 180th postnatal day respectively. The total number of pores per nucleus amounted to 1257, 6582, 5405 and 3384 on the 18--20th embryonic and the 15th, 50th and 180th postnatal day respectively. Thus the total number of pores per nucleus increases 5.2 times from the 18th--20th prenatal to the 15th postnatal day and than slightly decreases toward the 180th postnatal day. The density of pore complexes in adult brain cell nuclei is therefore very high in comparison with other normal somatic and cancer cells.