Grazing thin section through the nuclear envelope of a macronucleus. Nuclear pores are packed so tightly that they often form a hexagonal array with 6 pores surrounding a central pore. The pores often have electron opaque dots in their centers which indicate passage of ribonucleoprotein particles (RNP) between the nucleus and the cytoplasm. TEM taken on 1/4/82 by R. Allen with Hitachi HU11A operating at 75kV. Neg. 17,500X. Bar = 0.2µm.