Definition: Heterochromatin is a type of chromatin that contains two or more types of euchromatic and heterochromatic regions. Euchromatin is characterized by uniform distribution of euchromatin, while heterochromatin is composed of euchromatin and heterochromatin. The presence of both euchromatin and heterochromatin in the same cell can lead to a complex regulatory network that regulates gene expression and chromatin structure. Heterochromatin typically occurs in cells with