Placenta - Maternal Decidua
This page gives an overview of aspects of maternal component of placental development, formed initially by the decidualization of the endometrium.
In week 2, the trophoblast shell cells proliferate and form a syncitiotrophoblast and cytotrophoblast layer around the conceptus. Syncitiotrophoblast cells migrate into the uterine wall, forming maternal blood-filled spaces (lacunae).
Decidualization is the process of converting endometrial stromal cells into decidual cells and requires at least 8–10 days of hormone stimulation. A similar "decidual" cellular change, but less significant, also occurs in the uterine lining after ovulation during the secretory phase of the non-pregnant uterus.
- initiated during the mid-secretory phase of the menstrual cycle
- in response to elevated progesterone levels
- acts mainly through progesterone receptor (PR) PR-A (other isoform is PR-B)
Placentation begins once the conceptus begins to implant in the uterine wall and the placenta will have both a fetal and a maternal component.
During pregnancy, both the maternal blood volume increases by about 50% and the uterine blood flow increases 10 to 12 fold. Flow increase is due to the trophoblast cell invasion of the spiral arteries opening them into blood-filled spaces of the placenta.
The maternal uterine endometrium stromal cells (fibroblast-like) are transformed by steroid hormones (progesterone) and embryonic signals into the decidua.
The entire maternal decidua is divided into three regions: decidua basalis, decidua capsularis and decidua parietalis.
These 3 regions are named by their positional relationship to the conceptus.
- Preimplantation factor (PIF) secreted only by viable embryos.
- a 15 amino acid peptide MVRIKPGSANKPSDD
- regulates immunity, promoting embryo-decidual adhesion, and regulating adaptive apoptotic processes.
Member of the a transforming growth factor beta (TGFbeta) superfamily, contributes to human endometrial stromal cells (HESC) decidualization and has been localized to decidual cells in the human endometrium. (possibly also BMP2 and TGFbeta1)
Prokineticin 1 (PROK1) signalling via prokineticin receptor 1 (PROKR1) regulates Dickkopf 1 (DKK1) expression, a negative regulator of canonical Wnt signaling.
- Glossary: A | B | C | D | E | F | G | H | I | J | K | L | M | N | O | P | Q | R | S | T | U | V | W | X | Y | Z | Numbers | Symbols | Term Link
Cite this page: Hill, M.A. (2019, October 17) Embryology Placenta - Maternal Decidua. Retrieved from https://embryology.med.unsw.edu.au/embryology/index.php/Placenta_-_Maternal_Decidua
- © Dr Mark Hill 2019, UNSW Embryology ISBN: 978 0 7334 2609 4 - UNSW CRICOS Provider Code No. 00098G