Transmission electron micrograph of rat liver cell showing a grazing section through the nuclear envelope and illustrating the high density of nuclear pores in cells from a 1 day old animal. The cytop...

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...

A freeze-fractured view of the nuclear envelope. The fracture in the middle of the figure exposes the cytosolic facing membrane. This can be distinguished by a fractured cytoplasmic organelle at the t...

High resolution transmission electron micrograph of Halteria showing both the large macronucleus with nuclear pores, dense heterochromatin bodies and nucleolus, and the small micronucleus.

In one experiment in which electric shock was applied to Paramecium cells to trigger trichocyst discharge the macronucleus in one cell was observed to undergo morphological changes of two types. First...