Prophase

Definition

Prophase is the first stage of mitosis during which chromosomes condense and become visible under light microscopy; spindle fibers form and the nuclear envelope breaks down.

Related terms

Mitosis: This is a type of cell division that results in two daughter cells each having the same number and kind of chromosomes as the parent nucleus.

Chromosomes: These are thread-like structures located inside the nucleus of animal and plant cells. Each chromosome is made of protein and a single molecule of DNA.

Spindle Fibers: These are proteins that divide genetic material in a cell. They help pull apart the cell during replication and are necessary for cell division.