Decidua
Encyclopedia
Decidua is the term for the uterine
lining (endometrium
) during a pregnancy
, which forms the maternal part of the placenta
. It is formed under the influence of progesterone
and forms highly-characteristic cells.
deciduus, meaning falling off or shedding.
, in mammal
s, the endometrial lining becomes transformed into a secretory lining in preparation of accepting the embryo
. Without implantation, the secretory lining will be absorbed (estrous cycle
) or shed (menstrual cycle
).
With implantation the lining now termed decidua evolves further during the pregnancy.
The decidua is shed during the parturition process.
That part of the decidua that interacts with the trophoblast is the decidua basalis (also called decidua placentalis). The remainder of the decidua is termed the decidua parietalis or decidua vera. Also, there is the decidua capsularis, which grows over the embryo on the luminal side, enclosing it into the endometrium and surrounding the embryo together with decidua basalis.
The decidua has a histologically
-distinct appearance, displaying large polygonal decidual cells in the stroma. These are enlarged endometrial stromal cells, which resemble epithelium
(and are referred to as "epithelioid").
Formation of a specialized decidua is called decidualization
, which is a special property of endometrium seen only in hemochorial placentation.
Decidualization includes the process of differentiation of the spindle-shape stromal fibroblasts into the plump secretory decidual cells, which create a pericellular extracellular matrix rich in fibronectin and laminin (similar to epithelial cells).
Vascularity, as well as vascular permeability, is enhanced in the decidualizing endometrium.
Its leukocyte population is distinct, with the presence of large endometrial granular leukocytes being predominant, while polynuclear leukocytes and B-cells are scant.
The large granular lymphocytes (CD56 bright) are called "uterine NK cells" or "uNK cells" in mice, and "decidual NK cells" or "dNK cells" in humans.
The border to the trophoblast
is called Nitabuch’s layer.
. Further, the decidua has to allow a very controlled invasion of the trophoblast.
In invasive placental disorders like placenta accreta
decidualization have been consistently found to be deficient.
s, and cytokine
s. It has receptors for estrogen
, progesterone
, growth hormone
, and others.
Among its products are hormones commonly associated with other organs such as cortisol
, CRF
, GnRH, prolactin
, and relaxin
. Decidual prolactin is not under dopamine
rgic control.
Pregnancy protein 14 (PP-14), also called placental protein 12, and Insulin-like growth factor-binding protein 1(IGFBP1) appear to be specific products of the secretory and decidual lining.
Other factors released include interleukin
-15 and vascular endothelial growth factor
(VEGF). A reasonable understanding of the role and interplay of these hormones and factors has not been evolved.
of the decidua, chronic deciduitis
, is associated with preterm labour.
Uterus
The uterus or womb is a major female hormone-responsive reproductive sex organ of most mammals including humans. One end, the cervix, opens into the vagina, while the other is connected to one or both fallopian tubes, depending on the species...
lining (endometrium
Endometrium
-Function:The endometrium is the innermost glandular layer and functions as a lining for the uterus, preventing adhesions between the opposed walls of the myometrium, thereby maintaining the patency of the uterine cavity. During the menstrual cycle or estrous cycle, the endometrium grows to a...
) during a pregnancy
Pregnancy
Pregnancy refers to the fertilization and development of one or more offspring, known as a fetus or embryo, in a woman's uterus. In a pregnancy, there can be multiple gestations, as in the case of twins or triplets...
, which forms the maternal part of the placenta
Placenta
The placenta is an organ that connects the developing fetus to the uterine wall to allow nutrient uptake, waste elimination, and gas exchange via the mother's blood supply. "True" placentas are a defining characteristic of eutherian or "placental" mammals, but are also found in some snakes and...
. It is formed under the influence of progesterone
Progesterone
Progesterone also known as P4 is a C-21 steroid hormone involved in the female menstrual cycle, pregnancy and embryogenesis of humans and other species...
and forms highly-characteristic cells.
Etymology
The word comes from the LatinLatin
Latin is an Italic language originally spoken in Latium and Ancient Rome. It, along with most European languages, is a descendant of the ancient Proto-Indo-European language. Although it is considered a dead language, a number of scholars and members of the Christian clergy speak it fluently, and...
deciduus, meaning falling off or shedding.
Background
After ovulationOvulation
Ovulation is the process in a female's menstrual cycle by which a mature ovarian follicle ruptures and discharges an ovum . Ovulation also occurs in the estrous cycle of other female mammals, which differs in many fundamental ways from the menstrual cycle...
, in mammal
Mammal
Mammals are members of a class of air-breathing vertebrate animals characterised by the possession of endothermy, hair, three middle ear bones, and mammary glands functional in mothers with young...
s, the endometrial lining becomes transformed into a secretory lining in preparation of accepting the embryo
Embryo
An embryo is a multicellular diploid eukaryote in its earliest stage of development, from the time of first cell division until birth, hatching, or germination...
. Without implantation, the secretory lining will be absorbed (estrous cycle
Estrous cycle
The estrous cycle comprises the recurring physiologic changes that are induced by reproductive hormones in most mammalian placental females. Estrous cycles start after puberty in sexually mature females and are interrupted by anestrous phases or pregnancies...
) or shed (menstrual cycle
Menstrual cycle
The menstrual cycle is the scientific term for the physiological changes that can occur in fertile women for the purpose of sexual reproduction. This article focuses on the human menstrual cycle....
).
With implantation the lining now termed decidua evolves further during the pregnancy.
The decidua is shed during the parturition process.
Structure
Different layers of the deciduas have been described:- a compact outer layer (stratum compactum)
- an intermediate layer (stratum spongiosum)
- a boundary layer adjacent to the myometriumMyometriumThe myometrium is the middle layer of the uterine wall, consisting mainly of uterine smooth muscle cells , but also of supporting stromal and vascular tissue...
('Stratum Basalis').
That part of the decidua that interacts with the trophoblast is the decidua basalis (also called decidua placentalis). The remainder of the decidua is termed the decidua parietalis or decidua vera. Also, there is the decidua capsularis, which grows over the embryo on the luminal side, enclosing it into the endometrium and surrounding the embryo together with decidua basalis.
Histology
Histology is the study of the microscopic anatomy of cells and tissues of plants and animals. It is performed by examining cells and tissues commonly by sectioning and staining; followed by examination under a light microscope or electron microscope...
-distinct appearance, displaying large polygonal decidual cells in the stroma. These are enlarged endometrial stromal cells, which resemble epithelium
Epithelium
Epithelium is one of the four basic types of animal tissue, along with connective tissue, muscle tissue and nervous tissue. Epithelial tissues line the cavities and surfaces of structures throughout the body, and also form many glands. Functions of epithelial cells include secretion, selective...
(and are referred to as "epithelioid").
Formation of a specialized decidua is called decidualization
Decidualization
Decidualization is a characteristic of the endometrium of the pregnant uterus. It is a response of maternal cells to progesterone. Decidualization may be used to describe any change due to progesterone...
, which is a special property of endometrium seen only in hemochorial placentation.
Decidualization includes the process of differentiation of the spindle-shape stromal fibroblasts into the plump secretory decidual cells, which create a pericellular extracellular matrix rich in fibronectin and laminin (similar to epithelial cells).
Vascularity, as well as vascular permeability, is enhanced in the decidualizing endometrium.
Its leukocyte population is distinct, with the presence of large endometrial granular leukocytes being predominant, while polynuclear leukocytes and B-cells are scant.
The large granular lymphocytes (CD56 bright) are called "uterine NK cells" or "uNK cells" in mice, and "decidual NK cells" or "dNK cells" in humans.
The border to the trophoblast
Trophoblast
Trophoblasts are cells forming the outer layer of a blastocyst, which provide nutrients to the embryo and develop into a large part of the placenta. They are formed during the first stage of pregnancy and are the first cells to differentiate from the fertilized egg...
is called Nitabuch’s layer.
Role
As the maternal interface to the embryo the decidua participates in the exchanges of nutrition, gas, and waste with the gestation. It also protects the pregnancy from the maternal immune systemImmune system
An immune system is a system of biological structures and processes within an organism that protects against disease by identifying and killing pathogens and tumor cells. It detects a wide variety of agents, from viruses to parasitic worms, and needs to distinguish them from the organism's own...
. Further, the decidua has to allow a very controlled invasion of the trophoblast.
In invasive placental disorders like placenta accreta
Placenta accreta
Placenta accreta is a severe obstetric complication involving an abnormally deep attachment of the placenta, through the endometrium and into the myometrium...
decidualization have been consistently found to be deficient.
Hormone production
The decidua secretes hormones, growth factorGrowth factor
A growth factor is a naturally occurring substance capable of stimulating cellular growth, proliferation and cellular differentiation. Usually it is a protein or a steroid hormone. Growth factors are important for regulating a variety of cellular processes....
s, and cytokine
Cytokine
Cytokines are small cell-signaling protein molecules that are secreted by the glial cells of the nervous system and by numerous cells of the immune system and are a category of signaling molecules used extensively in intercellular communication...
s. It has receptors for estrogen
Estrogen
Estrogens , oestrogens , or œstrogens, are a group of compounds named for their importance in the estrous cycle of humans and other animals. They are the primary female sex hormones. Natural estrogens are steroid hormones, while some synthetic ones are non-steroidal...
, progesterone
Progesterone
Progesterone also known as P4 is a C-21 steroid hormone involved in the female menstrual cycle, pregnancy and embryogenesis of humans and other species...
, growth hormone
Growth hormone
Growth hormone is a peptide hormone that stimulates growth, cell reproduction and regeneration in humans and other animals. Growth hormone is a 191-amino acid, single-chain polypeptide that is synthesized, stored, and secreted by the somatotroph cells within the lateral wings of the anterior...
, and others.
Among its products are hormones commonly associated with other organs such as cortisol
Cortisol
Cortisol is a steroid hormone, more specifically a glucocorticoid, produced by the adrenal gland. It is released in response to stress and a low level of blood glucocorticoids. Its primary functions are to increase blood sugar through gluconeogenesis; suppress the immune system; and aid in fat,...
, CRF
CRF
CRF may refer to:Science and technology* Corticotropin-releasing factor, also called corticotropin-releasing hormone and corticoliberin, is a polypeptide hormone and neurotransmitter involved in the stress response...
, GnRH, prolactin
Prolactin
Prolactin also known as luteotropic hormone is a protein that in humans is encoded by the PRL gene.Prolactin is a peptide hormone discovered by Henry Friesen...
, and relaxin
Relaxin
Relaxin is a protein hormone first described in 1926 by Frederick Hisaw.The relaxin-like peptide family belongs in the insulin superfamily and consists of 7 peptides of high structural but low sequence similarity; relaxin-1 , 2 and 3 , and the insulin-like peptides, INSL3, INSL4, INSL5 and INSL6...
. Decidual prolactin is not under dopamine
Dopamine
Dopamine is a catecholamine neurotransmitter present in a wide variety of animals, including both vertebrates and invertebrates. In the brain, this substituted phenethylamine functions as a neurotransmitter, activating the five known types of dopamine receptors—D1, D2, D3, D4, and D5—and their...
rgic control.
Pregnancy protein 14 (PP-14), also called placental protein 12, and Insulin-like growth factor-binding protein 1(IGFBP1) appear to be specific products of the secretory and decidual lining.
Other factors released include interleukin
Interleukin
Interleukins are a group of cytokines that were first seen to be expressed by white blood cells . The term interleukin derives from "as a means of communication", and "deriving from the fact that many of these proteins are produced by leukocytes and act on leukocytes"...
-15 and vascular endothelial growth factor
Vascular endothelial growth factor
Vascular endothelial growth factor is a signal protein produced by cells that stimulates vasculogenesis and angiogenesis. It is part of the system that restores the oxygen supply to tissues when blood circulation is inadequate....
(VEGF). A reasonable understanding of the role and interplay of these hormones and factors has not been evolved.
Other
- In case of an extrauterine pregnancy, the endometrium nevertheless becomes decidualized. A woman may shed the lining in the form of a decidual cast, which may be mistaken as a miscarriageMiscarriageMiscarriage or spontaneous abortion is the spontaneous end of a pregnancy at a stage where the embryo or fetus is incapable of surviving independently, generally defined in humans at prior to 20 weeks of gestation...
, when, in fact, the ectopic still persists. - A decidual reaction can be observed in tissue of the peritoneumPeritoneumThe peritoneum is the serous membrane that forms the lining of the abdominal cavity or the coelom — it covers most of the intra-abdominal organs — in amniotes and some invertebrates...
and ovaryOvaryThe ovary is an ovum-producing reproductive organ, often found in pairs as part of the vertebrate female reproductive system. Ovaries in anatomically female individuals are analogous to testes in anatomically male individuals, in that they are both gonads and endocrine glands.-Human anatomy:Ovaries...
during a pregnancy, and represents a response of stromal tissue to progesterone. - Decidua in a lymph node may mimic metastaticMetastasisMetastasis, or metastatic disease , is the spread of a disease from one organ or part to another non-adjacent organ or part. It was previously thought that only malignant tumor cells and infections have the capacity to metastasize; however, this is being reconsidered due to new research...
carcinomaCarcinomaCarcinoma is the medical term for the most common type of cancer occurring in humans. Put simply, a carcinoma is a cancer that begins in a tissue that lines the inner or outer surfaces of the body, and that generally arises from cells originating in the endodermal or ectodermal germ layer during...
.
Pathology
A long-lasting infectionInfection
An infection is the colonization of a host organism by parasite species. Infecting parasites seek to use the host's resources to reproduce, often resulting in disease...
of the decidua, chronic deciduitis
Chronic deciduitis
Chronic deciduitis, also plasma cell deciduitis, is a type of long-lasting inflammation that arises in pregnancy and affects the endometrial stromal tissue ....
, is associated with preterm labour.