What is Called Decidua?
The decidua is the specialized layer of the endometrium (the lining of the uterus) that forms during pregnancy. It's essentially a modified uterine lining that prepares for and supports the developing embryo and placenta. Think of it as the maternal component of the placenta's foundation.
Several key aspects define the decidua:
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Role in Pregnancy: The decidua plays a crucial role in supporting the developing embryo. It provides nourishment and protection, shielding the embryo from the mother's immune system. The corpus luteum of the ovary (initially) and the placenta (later) produce progesterone, triggering the decidual reaction in the endometrial stromal cells – causing modifications and vascular changes that create the decidua. [Source: ScienceDirect Topics, Merriam-Webster, NCBI Bookshelf]
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Structure and Composition: The decidua is not a uniform layer. It's divided into three parts based on location:
- Decidua basalis: The layer underlying the implanted embryo, forming the maternal part of the placenta.
- Decidua capsularis: The layer covering the implanted embryo.
- Decidua parietalis: The remaining portion of the endometrium. [Source: NCBI Bookshelf, University of Michigan Medical School]
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Shedding and Decidual Cast: After childbirth or miscarriage, the decidua sheds. In some cases, this shedding can take the almost exact shape of the uterine cavity, forming what's known as a decidual cast. [Source: Cleveland Clinic, WebMD]
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Immune Protection: The decidua plays a vital role in protecting the embryo from rejection by the mother's immune system. [Source: NCBI PMC]
Decidua Beyond Pregnancy
While primarily associated with pregnancy, the term "decidua" has other meanings:
- In botany: Larix decidua, also known as European larch, is a deciduous conifer. This highlights that the term "decidua" relates to shedding or falling off, a characteristic shared by the uterine lining in pregnancy and some plants. [Source: Missouri Botanical Garden]
