1. Nucleolus: This is a dense, spherical structure within the nucleus. It is responsible for the production of ribosomes, which are essential for protein synthesis.

2. Chromatin: This is a complex of DNA and proteins that make up the chromosomes. It contains the genetic information of the cell and is responsible for directing cellular activities.

3. Nuclear Envelope: This is a double membrane that surrounds the nucleus and separates it from the cytoplasm. It regulates the movement of molecules between the nucleus and the cytoplasm, and it also provides structural support for the nucleus.