Human Decidua And Decidualisation

Human Decidua And Decidualisation 

1.The formation of a specialised decidua from endometrium the normal lining of the non-
pregnant uterus is called decidualisation (1).
Decidualisation includes the process of differentiation of spindle-shaped stromal cells of
the endometrium into the plump secretory decidual cells, which create a pericellular and
entracellular matrix rich in fibrorectin and laminin (1).
Vascularity, as well as vascular permeability, is enhanced in the decidualising endometrium
(1).
It’s leukocyte population is distinct with the pressure of large endometrial granular
leukocytes and B-cells are scant. These large granular lymphocytes (CD56bright) are called
“uterine NK cells” or LGL cells (1).

Role of the Human Decidua

At the maternal interface to the embryo the decidua participates in the exchanges of
nutrition, gas and waste with embryo. It also protects the pregnancy from the maternal
immune system. Further the decidua has to allow a very controlled invasion by the
trophoblast (1).

2. Changes in human endometrium are essential to allow the establishment of pregnancy.
These changes are induced in vivo by progesterone and include appearance within the
tissue of a specific uterine natural killer cell characterised by an abundant expression of
CD56. Changes also occur in the stroma cells, which undergo a characteristic
decidualisation reaction. Decidualised stroma cells are derived from the fibroblast like cells
within the endometrium which maintain their progesterone receptors in the presence of
progesterone. In vitro elevated intracellular cAMP as well as progesterone is necessary for
decidualisation. In vivo these changes may be provided by progesterone from the corpus
luteum and by Prostoglandin E2, a stimulator of adenyl cyclase and relaxin which has been
shown to be a phosphodiasterase inhibitor (2).

3. Decidual layer identified constantly at 5-6 weeks of gestation. Thickness peaked at 6-7 weeks.
It was seen inconsistently at 8-9 weeks and was not identified at 10 weeks. There is a window
of opportunity in the first trimester for sonographic examination of the decidua. This will allow
screening at an early stage for conditions that effect the decidua during pregnancy. 105 women
with uncomplicated pregnancies who later delivered at term (3). 


 WONG H S, CHEUNG Y K, TAIT J.

Sonographic study of decidua basalis in the first trimester pregnancy.

Ultrasound Obstet Gynecol 2009;33(6):634-7

4. Human trophoblast cells are sensitive to lysis by IL-2 stimulated decidual NK cells. The
majority if decidual white cells are potential killer cells. The major population of leucocytes
present during the time that the extra villous trophoblast infiltrates the decidua are uterine large
granulated lymphocytes (LGL) which constitute 70% of the decidual white cells CD+56
LGL/NK cells, together with 20% macrophages and a few CD3 + T cells 10%. The relative
surface density of CD+56 is greatly increased in decidual LGL to 22 times that found in
peripheral classic NK cells. Peripheral LGL’s also respond to interleukin2 (IL-2) by
proliferating and becoming potent lymphokine activated killer cells capable of greatly increased
killing of K562 cells. They will also kill cytotrophoblast cells (4).


5. Decidual CD-16 CD56 Bright NK cells possess a high affinity receptor for IL-2. These NK cells have both interleukin-2 receptors, alpha and beta (5). Their NK activity is markedly elevated even by treatment with small amounts of IL-2. These cells have high affinity for IL- 2 (5). Therefore there needs to be suppression if IL-2 cytokine at the feto-maternal interface (5).

6. Decidual endometrium includes endometrial granulocytes was not apparent in
choriocarcinoma. Fetal trophoblast antigen expression in both molar pregnancy and
choriocarcinoma has been shown to obey the same general principles according to
morphological and anatomical classification as previously described for normal pregnancy.
Choriocarcinoma contained syncytio and cytotrophoblastic elements but no villous structure
(6).

REFERENCES

1. Human Decidua and Decidualisation, from Wikipedia the free encyclopedia.


2. DUNN C L, KELLY R N, CRITCHLEY H D.
Decidualisation of human endometrial stroma cells: an enigmatic transformation.
Reprod. Biomed. Online 2003;7(2):151-61.


3. WONG H S, CHEUNG Y K, TAIT J
Sonographic study of decidua basalis in first trimester pregnancy.
Ultrasound Obstet. Gynecol. 2009;33(6):634-7.


4. LOKE Y W, KING A
Recent developments in human materno-fetal immune interaction.
Current opinion in immunology. 1991;3:762- 766.


5. SAITO S, MORII T, ENOMOTO M, SAKAKURA S, NISHIKAWA K
NANTA N, ICHIJO M
The effect of interleukin-2 and transforming growth factor B2 (TG-F-B2) on the proliferation and natural killing activity of decidual CD-16 CD56 Bright natural killer cells.
Cell Immunol. 1993;152:605-613.


6. BULMER J N
Immuno histochemical studies of fetal trophoblast and maternal decidua in hydatidiform mole and choriocarcinoma.
Placenta 1988;9:183-200.

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