Placenta Flashcards
Explain follicular phase
dec luteal prod. of progesterone & inhibin A
inc FSH
growth & selection of antral follicles
LH surge inc progesterone & prostaglandin
LH induce theca cell to prod more androstenedione then converted to estrogen in granulosa
as estrogen rise, negative feedback to hypothalamus & ant. pituitary, dec FSH & LH
inc prod inhibin B further dec FSH
Explain ovulation
devt of corpus luteum
dec FSH & LH
granulosa enhance estrogen & progesterone prod
NO fertilization:
- luteolysis (9-11 d)
- dec steroid hormone
- repeat cycle
fertilization:
- HCG prevent luteolysis
- maintain progesteroneExplain proliferative phase
estrogen phase toward end of mens proliferation of SM & inc vascularity endometrial glands are elongated with narrow lumen utz: trilaminar appearance
Explain early secretory phase
secrete mucus & glycogen
glands are tortuous and spiral arteries extends to superficial layers
utz: thickest endometrial layer
Explain late secretory phase
dec progesterone & estrogen
lots of glycogen lots of vacuole
Explain menstrual phase
spiral arteries rupture
endometrium sloughed off
when is the best time to get an endometrial sample?
1-4 days prior to menstruation
what happens to endometrium if the woman becomes pregnant?
endometrium transform into decidua
3 parts of decidua
decidua basalis
- between embryo & myometrium
- passageway of nutrition
decidua capsularis
- bet. embryo & uterine lumen
decidua parietalis
- side of uterus away from embryofunctions of decidua
nutritional support & excretion
protein & steroid synthesis
controls trophoblastic invasion
implantation
6-7 days after fertilization
stages of implantation
apposition
- most common site is the upper and posterior wall in mid-sagittal plane
adhesion
- d20-21
invasion
- spiral arteries reconstruction
decidualizationday 8
trophoblast differentiation into cytotrophoblast & syncytiotrophoblast
embryoblast differentiation into hypoblast & epiblast
day 9
first vacuole
lacunar stage
primitive yolk sac
day 11-12
primary villi formation
sinusoids
extraembryonic mesoderm
day 13
secondary villi formation
chorionic cavity
by 2nd wk of life, what supplies the implanted ovum in uterus?
lacunar system
3rd wk of gestation
vascularization
chorionic villin into extravillous trophoblast
tertiary villus or definitive placental villus
4th wk of gestation
CVS formation, true circulation is established
remodelling of spiral arteries
cytotrophoblast invade spiral arteries and replace maternal endothelium
5th wk of gestation
capillary network dominates villi (V>C)
drainage into sinus venosus
what is the main functional component of placenta?
trophoblast
week 7
trophoblast proliferated into villi
week 8
villus chorion or chorion frondosum
what is the maternal and fetal side of placenta?
M: decidua basalis, uterine vessel & glands
F: chorionic plate (amnion & trophoblast)
placental growth
w/c trimester is more rapid?
what wk, placental and fetal wt is equal?
what is the placental wt at term?
1st trim. more rapid
17th wk placenta = fetal
1/6 fetal weight at term
placental maturation
what wk does it calcified?
grading base from week
end of 42nd wk: placenta gets calcified
Gr 0: immature (<18wks)
Gr 1: indentations of chorionic plate (18-29wks)
Gr 2: comma like densities (30-38wks)
Gr 3: severely calcified; ring-like structure (>39wks)
what is responsible for proliferation and devt of placenta?
leptin or adiponectin
what is the fetal macrophages?
hofbauer cells
week 6
chorion laeve
2 placental plates
chorionic plate: internal; lined by amniotic membrane; umbilical cord lies to this plate
basal plate: maternal
differentiate vasculogenesis & angiogenesis
V: de novo formation of BV from mesodermally derived precursor cells
A: expansion of preexisting vessel bed & creation of new vessel branches from preexisting ones
angiogenesis category
branching: 0-24wks; primitive capillary network; VEGF
nonbranching: 24wks; mature intermediate villi & later terminal villi; PIGF
explain the 3 placental hypoxia
preplacenta: mother, placenta & fetus are hypoxic; inc peripheral branching
uteroplacenta: placenta & fetus are hypoxic, normoxic mother; d/t VEGF upregulation
postplacenta: normoxic mother, hyperoxic placenta, hypoxic fetus; terminal villi capillary branching almost absent
physiologic changes in uteroplacental arteries
trophoblastic invasion
loss of elasticity
dilatation
loss of vasomotor control
explain circulation in intervillous space
uterine contraction: vein is occluded, arterial blood forced into intervillous space
uterine relaxation: venous drainage
spiral arteries are perpendicular & veins are parallel to uterine wall
explain fetoplacental circulation
umbilical arteries are deoxygenated from fetus to IVS
umbilical vein are oxygenated from IVS to fetus
differentiate thin zone & thick zone in placental barrier
thin alpha zone: gas exchange
thick beta zone: hormone synthesis
hormones synthesized by placenta
hCG hPL ACTH hCG-V PTHP-rP calcitonin relaxin inhibin, activins, cytokines, ANP TRH GnRH CRH GHRH
what is the major site of steroid & CHON production in placenta?
syncytiotrophoblast
source of placenta in progesterone biosynthesis
maternal LDL-C
source of placenta in estrogen synthesis
C19 steroids from maternal & fetal adrenal glands
what maintains corpus luteum in pregnant women? in nonpregnant women?
P: hCG
NP: LH
explain hCG levels in pregnancy
detected: 8 d
doubles q48h
max: 10 wks
min: 16 wks
explain hPL levels in pregnancy
detected: 3 wks
max: 36 wks
fx of hCG
maintains corpus luteum stim leydig to prod testosterone immunosuppressive action stim maternal thyroid growth of umbilical cord
fx of hPL
promotes maternal lipolysis insulin resistance glucose spared to fetus promotes growth of breast marker for placental functioning
explain hGH-V levels in pregnancy
present: 21-26 wks
max: 36 wks
fx hPL
growth promoting & anti-lipogenic fx
explain activin & inhibin levels in pregnancy
peak at term
fx of activin & inhibin
A: stim placental hormone production
I: opposes activin
fx of placental ACTH
imp for controlling fetal lung maturation & parturition timing
CRH stim prostaglandin prod & ACTH secretion
describe decidual NK cells
lacks cytotoxic fx
dampen Th17 cells
express IL-8 & interferon 10 (invasion)
prod VEGF & PIGF
describe decidual macrophages
inhibit typical NK cells
spiral artery remodelling
engulf apoptotic cells
describe T cell apoptosis (FasL)
clonal deletion of immune cells that recognize paternal Ags
describe regulatory T cells
prevent immunological rejection of fetus
CCR4
modify fx of APC thru CTLA4-B7 w/c upregulates IDO
describe PDL 1
regulates T cell homeostasis
imp in peripheral tolerance & prevention of autoimmunity
dec PDL1 results in dec fetal survival
3 mechanisms of fetomaternal tolerance
lack MHC molecules on trophoblast
trophoblast HLAs
T-cell apoptosis
px with frequent hx of abortion, what can be given (2-3 days postfertlization)?
progesterone
G1P0 w/ hypogastric cramps, amenorrheic for 6wks, positive PT. Utz 8cm right adnexal mass cystic w/ solid component. approach?
observe then remove mass after 10 wks
milestones per week
1st wk: blastocyst, cytotrophoblast, syncytiotrophoblast, disappearance of zona pellucida
2nd wk: implantation (apposition), lacuna to tertiary villi
3rd-4th wk: septation
starved pregnant women, IUGR or maldevt of brain?
mental retardation
