BGDA Practical Placenta - Maternal Decidua: Difference between revisions
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* deposition of fibrinoid and glycogen and epithelial plaque formation (at anchoring villi) | * deposition of fibrinoid and glycogen and epithelial plaque formation (at anchoring villi) | ||
* presence of decidual cells are indicative of pregnancy | * presence of decidual cells are indicative of pregnancy | ||
Fibrinoid layer - (Nitabuch's layer) is thought to act to prevent excessively deep implantation. | |||
Cervix - at mouth of uterus, secretes mucus (CMP), forms a plug/barrier, mechanical and antibacterial | Cervix - at mouth of uterus, secretes mucus (CMP), forms a plug/barrier, mechanical and antibacterial |
Revision as of 23:37, 3 June 2012
Practical 14: Implantation and Early Placentation | Villi Development | Maternal Decidua | Cord Development | Placental Functions | Diagnostic Techniques | Abnormalities |
Content to be added.
Uterus
Menstrual Changes
- Endometrium - 3 layers in secretory phase of menstrual cycle: compact, spongy, basal
- Myometrium - muscular layer outside endometrium, contracts in parturition
- Perimetrium - tunica serosa of the uterus continuous with the peritoneal wall
Endometrial Layers
- Compact - implantation occurs in this layer, dense stromal cells, uterine gland necks, capillaries of spiral arteries.
- Spongy - swollen stromal cells, uterine gland bodies, spiral arteries.
- Basal - not lost during menstruation or childbirth, own blood supply.
Uterine glands
- still well-developed and highly active at 6 weeks (GA).
- gradually regress in length and epithelium height as the first trimester advances.
Decidual Reaction
- occurs initially at site of implantation and includes both cellular and matrix changes
- reaction spreads throughout entire uterus, not at cervix
- deposition of fibrinoid and glycogen and epithelial plaque formation (at anchoring villi)
- presence of decidual cells are indicative of pregnancy
Fibrinoid layer - (Nitabuch's layer) is thought to act to prevent excessively deep implantation.
Cervix - at mouth of uterus, secretes mucus (CMP), forms a plug/barrier, mechanical and antibacterial Vascular - increased number of blood vessels
Decidua
The endometrium becomes the decidua and forms 3 distinct anatomical regions (at approx 3 weeks)
- Decidua Basalis at implantation site
- Decidua Capsularis enclosing the conceptus
- Decidua Parietalis the remainder of uterus
- Decidua Capsularis and Parietalis fuse eventually fuse and uterine cavity is lost by 12 weeks
Placental Classification
Classification of placenta is on the basis of histological (microscopic) structural organization and layers between fetal and maternal circulation.
Three main groups:
- Haemochorial - placenta where the chorion comes in direct contact with maternal blood (human).
- Endotheliochorial - maternal endometrial blood vessels are bare to their endothelium and these comes in contact with the chorion (dogs, cats).
- Epitheliochorial - maternal epithelium of the uterus comes in contact with the chorion, considered as primitive (pigs, cows).
The presence of these three differing types of placenta have also been used to describe the pattern mammalian evolution.
Maternal Blood Vessels
Additional Information
Fibrinoid
Exist as 2 forms of extracellular matrix:
- Fibrin-type fibrinoid is a maternal blood-clot product which replaces degenerative syncytiotrophoblast
- Matrix-type fibrinoid is secreted by invasive extravillous trophoblast cells.
Fibrinoid layer (Nitabuch's layer) is thought to act to prevent excessively deep implantation.
Decidualization - process of endometrial stromal cells (fibroblast-like) change in morphology (polygonal cells) and protein expression and secretion (specific decidual proteins: prolactin, insulin-like growth factor binding protein-1, tissue factor, interleukin-15, and VEGF).
- Estrogen and progesterone - receptive phase, luminal and glandular epithelial cells change in preparation for blastocyst adplantation.
- Human Chorionic gonadotropin - luminal epithelium endoreplication leading to epithelial plaque formation.
- Human Chorionic gonadotropin - trophoblast invasion and decidualization of human stromal fibroblasts.
Artery Dilatation - due to extravillous trophoblast cells invading uterine wall and maternal spiral arteries replacing both smooth muscle with fibrinoid material and part of vessel endothelium. There is also a proliferation of maternal blood vessels.
Other changes
- Endoreplication - rounds of nuclear DNA replication without intervening cell or nuclear division (mitosis).
- Cytokines - of maternal origin also act on placental development.
- Natural Killer (NK) cells - 30% of all the decidual cells towards the end of the first trimester of pregnancy. These lymphocytes are present in the maternal decidua in large numbers (70%, normal circulating blood lymphocytes 15%) close to the extravillous trophoblast cells. Have a cytolytic potential against virus-infected and tumor-transformed cells.
Terms
Practical 14: Implantation and Early Placentation | Villi Development | Maternal Decidua | Cord Development | Placental Functions | Diagnostic Techniques | Abnormalities |