A small part of a nucleus, which is the center of a cell.
Subnuclei are important parts of a cell, like tiny pieces of a puzzle that make the whole picture.
Examples:
The subnucleus is like a small piece of the cell's center.
Scientists study the subnucleus to learn about cells.
The subnucleus helps the cell do its job.
The subnucleus is so small, you need a special tool to see it.
The subnucleus is like the tiny heart of the cell.
The subnucleus is very important for the cell, even though it is very small.