Decidua

**Definition:** The hormone-responsive glandular layer of ENDOMETRIUM that sloughs off at each menstrual flow (decidua menstrualis) or at the termination of pregnancy. During pregnancy, the thickest part of the decidua forms the maternal portion of the PLACENTA, thus named decidua placentalis. The thin portion of the decidua covering the rest of the embryo is the decidua capsularis.

**Tree numbers:** - A05.360.319.679.490.373 - A16.710.289

**Synonyms:** - Deciduum