Definition of Facultative heterochromatin

Facultative heterochromatin: Chromosome material that can be either heterochromatin or euchromatin.

The inactive X chromosome is made up of facultative heterochromatin. When a woman transmits that X chromosome to a son, the chromosome reverts to the euchromatic state and to genetic activity.


Last Editorial Review: 6/14/2012

Search MedTerms:


Back to MedTerms online medical dictionary A-Z List
Pill Identifier Tool

Need help identifying pills and medications?
Use the pill finder tool on RxList.

STAY INFORMED

Get the Latest health and medical information delivered direct to your inbox!