Placenta Flashcards
(38 cards)
Which cell type in placenta secretes hormones?
Trophopblast
Trophoblasts secrete what?
growth factors, immuno modulators, sex steroids, metabolic mediators (leptin, lactogen), neuromodulators (CRF and seratonin)
Placenta has receptors for what hormones?
glucocorticoids, insulin, insulin like growth factors, leptin, gonadal hormones, cytokines, prostaglandins
One big difference between human v rat placenta?
synthesis of estrogen
placentas can be classified as
epitheliochorial, endotheliochorial, hemochorial (based on which of mother’s cells contact fetal trophoblast)
Blood route in placenta
maternal blood enters the placenta from the uterus through the myometrium into the metrial gland, crosses the decidua, reaches the labyrinth layer, drains via the venous sinuses traversing the junctional zone into the decidua and exits via the metrial gland and the myometrium to the uterus
functions of placenta
(1) to ensure delivery of maternal nutrients and blood gas (O2 and CO2) to the placenta, (2) to transfer nutrient and oxygen from the placenta to the developing fetus, (3) to produce hormones and growth factors, and (4) to protect the developing fetus against infections
main components of rat placenta
decidua /metrial gland (maternal origin)
yolk sac, amnion membranes, basal zone (junctional zone)
labryinth and junctional zone (fetal, basal zone)
Trophoblast (consists of cytotrophoblast, syncytiotrophoblast) describe each
cyto: slowing the maternal blood,
sync: Main site of exchange,form a layer that separates fetal and maternal circulation
junctional zone function
production of steroids and peptide hormones
Spongiotrophoblast
Main structural component of the basal zone
Trophoblastic giant cells They are below the spongiotrophoblast layer, Phagocytic activity to mediate implantation, Major endocrine cell of the placenta
Glycogen cells
decidua function
decidual stromal cells
produce pro- and anti- inflammatory cytokines, immune cells, growth factors and hormones
commonalities/diff between rat and human placenta
discoid in shape, hemochorial
differing names of structure: labryinth vs placental villi
basal zone v basal plate
labryinth v villous
rat placenta absence of aromatase !
rat is antimesometrial
histological stages of human chorioamnionitis
Stage 1: lesion characterized by presence of neutrophils in the chorion or subchorionic space
Stage 2: a cluster of microabscessesneutrophilic infiltration of the chorionic connective tissue and/or amnion or chorionic plate
Stage 3: necrotizing chorioamnionitis with degenerating neutrophils
What % of cells make up the leukocytes in chorioamnionitis?
60% neutrophils
10% macrophage
15% t cells
neutrophils employ what in their defense?
NETs, ROS, antimicrobial enzymes, defensins, neutrophil elastase, myeloperoxidase
Whats in the labyrinth?
trophoblast (cytotrophoblast, cyncitiotrophoblast)
What’s in the junctional zone?
spongio trophoblast, glycogen cells, trophoblastic giant cells
do fetal capillaries penetrate into the JZ?
no
PMNs have three important antimicrobial functions:
phagocytosis, degranulation, and the release of material via neutrophil extracellular traps composed mainly of DNA from neutrophils trapping pathogens
major diff bw rat and placenta?
human more invasive: with only one layer of trophoblast separating the maternal blood from fetal endothelial cells as compared to three layers in rodents
What is sterile inflammation in the context of pregnancy?
Sterile inflammation refers to an immune response characterized by activation of inflammatory pathways in the absence of viable microbial infection. It can be induced by exposure to pathogen-associated molecular patterns (PAMPs) from inactive or non-replicating bacteria, such as heat-killed Group B Streptococcus (GBS), leading to placental dysfunction and adverse pregnancy outcomes.
Why are pregnant women more susceptible to infections
- Immune system modulation
Pregnancy doesn’t suppress the immune system—it modulates it:
The immune system shifts to tolerate the fetus (which is genetically half foreign).
There is a tilt toward anti-inflammatory responses in early and mid-pregnancy (to allow implantation and growth), followed by a pro-inflammatory phase in late pregnancy (to prepare for labor).
- Hormonal changes
Increased levels of progesterone and estrogen can alter immune responses and mucosal barrier integrity, sometimes reducing local defenses.
why is Group B Streptococcus (GBS) screening performed between 35-37 weeks of gestation?
The GBS screening swab is performed between 35-37 weeks because colonization status can fluctuate during pregnancy, and screening close to delivery provides the most accurate prediction of neonatal exposure risk, allowing timely intrapartum antibiotic prophylaxis to prevent early-onset neonatal GBS disease.
How does GBS activate the NF-κB pathway in placental cells?
Through TLR recognition of bacterial components, triggering downstream signaling cascades that activate NF-κB and promote proinflammatory cytokine production.
