Implantation 6 Flashcards
List the gross and histologic features of a normal placenta.
1
Q
What are the major components of the placenta?
A
- Membranes
- Umbilical cord
- Placental disc
2
Q
What are the major membranes of the placenta?
A
-
Amnion
- lines amniotic sac
- single layer of cuboidal epithelium, basement membrane, and collagen layer
-
Chorion
- fibrous chorion and a layer of extravillous trophoblast
- lies deep to the amnion and has sparsely cellular collagen layer
-
Decidual layer
- maternal in origin
- contains decidualized maternal cells, vessels, fibrin
- some degree of hemorrhage here
3
Q
Describe the histology of the umbilical cord.
A
- Single layer of cuboidal amniotic epithelium on the outer surface
- Three vessels, 2 arteries and a veinembedded in a myxoid paucicellular matrix called Wharton’s gelly
- proteoglycans with some fibroblasts and macrophages
- vein carries nutrient rich blood to fetus
- arteries carry deoxygenated blood and waste products back to placenta
- Can show remnant blood vessels (vitelline) and epithelial remnants (omphalomesenteric and allantoic in origin
4
Q
What are the major components of the placental disk?
A
- Chorionic plate
- Basal plate
5
Q
Describe the histological features of the chorionic plate.
A
- Single layer of cuboidal amniotic epithelium overlying a paucicellular collagenous matrix (fibrous chorion)
- Below are fetal villi separated by blood containing spaces where maternal blood circulates around fetal villi (intervillous space)
- stem villi - fetal vessels with smooth muscle layers
- terminal villi - only have capillaries
- outer layer of syncitiotrophoblast cells
- true syncytium, no membranes separating nuclei
- inner layer is cytotrophoblast cells that act as stem cells, become less numerous as development progresses
- Macrophages (Hofbauer cells) and fibroblasts in cellular matrix of villi
6
Q
Describe the histological features of the basal plate of the placental disk.
A
- Extravillous trophoblast cells
- Decidualized maternal cells
- maternal endometrial stromal cells
- form interface between fetal tissues and maternal myometrium
- Two well defined fibrinoid layers
- Rohr’s fibrinoid and Nitabuch’s fibrinoid (deeper layer)
- Maternal vessels