1.3 Placenta, Fetal membranes, Placental Hormones Flashcards
signals the start of cascade of events that will ensure the nourishment and growth of the product of conception
Fertilization
What is the product of conception
zygote
what day after fertilization where zygote is cleaved into blastomeres?
day 0-2
day when morulla is formed and enters uterine cavity
Day 3
What is formed during day 4-5?
Blastocyst
what is the fate of:
a) inner cell mass
b) outer cell mass
a) embryo
b) trophoblast
this event is signalled by the disappearance of the zona pellucida
implantation of blastocyst
the adhesion to the endometrial epithelium of the blastocyst (commonly at he upper posterior wall of uterus)
Apposition
Apposition occurs when?
day 5-6
at this day (a), the blastocyst is completely enveloped by maternal endometrium which is called (b)
a) day 9
b) decidua capsularis
at this day,the trophoblast is contiguous with the endometrium forming a syncytium
day 10
what are the 2 distinguishable layers of trophoblast and categorize to which side (maternal, embryonic)
Syncytiotrophoblast (Maternal side)
Cytotrophoblast (Embryonic side)
when does the layers of trophoblast become distinguishable?
Day 12
this provide the attachment of blastocyst to the decidua
trophoblast
trapped to form lacunae which soon become filled with blood
Spiral arteries (maternal)
subdivision of extravillous trophoblasts
Endovascular
Interstitial
invade and transform spiral arteries during pregnancy to create low resistance blood flow
Endovascular Trophoblasts
what do interstitial trophoblast invade specifically?
invade DECIDUA and SPIRAL ARTERIES
it is a period where the lacunae join together to form a complicated labyrinthem partitioned by solid trophoblastic columns
Lacunar Period
Lacunae will soon become the?
intervillous spaces
What are the cascade of events that happens during the 12th day of conception? (5)
- distinguished trophoblast (Syncytio and Cyto)
- distinguished embryonic poles (outer and inner)
- Trophoblastic invasion of the spiral arteries
- division of trophoblast outside the villus
- Lacunar period
characterized by the formation of primary and secondary villi (days)
13-19
what is the origin of primary villus?
solid cellular columns (from lacunar period)
What is the origin of the secondary villus?
when solid stalks (primary villus) are invaded by mesenchymal chord
what is the fate of the body stalk?
forms the Umbilical cord
the fetal membrane closest to the heart
Amnion
when does maternal blood enter the intervillous space?
day 14-15
this phenomenon is necessary for the intrauterine oxygen exchange. manner by which blood enters the intervillous space via the spiral arteries
Fountain-like burst
what are the cascade of events during the 13-19 post fertilization?
- Primary villus formation
- secondary villus formation
- Body stalk formation
- Amnion formation
- maternal blood enters intervillous space in a fountain like burst manner
what is formed when there is angiogenesis in the mesenchymal cores
tertiary villus
What is the pathology when there is absence of angiogenesis (failure of tertiary villus to form)
Hydatid mole (H. mole)
What are the clinical features of H.mole?
Ectopic pregnancy
Bleeding
Abortion
when does the fetoplacental circulation establishes itself?
day 17
What are the events that occur during 19-21 days postfertilization?
- formation of tertiary villi
- formation of fetal capillaries
- fetoplacental circulation
what completes the formation of fetoplacental circulation?
connection of blood vessels of the embryo to the chorionic blood vessels
what happens during days 21-40?
- formation of Chorionic frondosum
- roof and floor formation of the intervillous space
- formation of placental septa
the proliferation of chorionic villi that is in contact with the decidua basalis forms?
Chorionic frondosum
what is the other term for chorionic frondosum?
Leafy chorion
the roof and floor components of the intervillous spaces are composed of?
Roof: chorionic plate
Floor: cytotrophoblasts from the cell column
it consists of decidual tissue encasing trophoblastic elements with fetal and maternal componnets
Placental Septa
Day 40-50 events
- cotyledon formation
2. fromation of chorion laeve
which of the following forms the placental cotyledon?
a) stem villi
b) anchoring villi
Stem villi
blood supply and venous nature of the chorion frondosum at the endometrial cavity is lost which forms the?
Chorion Laeve
Decidua capsularis + decidua parietalis
Decidua Vera
time frames of Early pregnancy and Late pregnancy clinically.
Early pregnancy 8weeks
Describe the following in the Early pregnancy
- Syncytial layer
- Cytotrophoblast
- Hobauer cells
- Chronic stroma
- Fetal capillaries
- thick
- increase prominence, volume
- increase prominence, volume
- increase Abundance, loose
- decrease prominent, number
*typically LATE PREGNANCY has the opposite findings.SO MEMORIZE!
the fetal surface of the placenta is covered by the
Amnion
there is no connection between maternal circulation and fetal circulation. T/F
True
a low resistance unit that allows the exchange of oxygen as blood stays in the placenta
Placental Circulation
this organ ensures blood supply to the fetus during labor
Placenta
what is the course fetal circulation
Umbilical artery Mother oxygenated blood umbilical vein deoxygenated blood
when does end diastolic flow appear in the umbilical artery?
week 10
deoxygenated blood from the fetus course through the _____ to the mother
2 umbilical arteries
what are the charateristics of the amnion at term/birth?
Tough
pliable
tenacious
T/F.the amnion is vascularized.
False
it provides most of the tensile strength of fetal membranes
Amnion
the amnion is identifiable at what day of pregnancy?
7th-8th day
the acellular outer layer of the amnion is called
Zona spongiosa
which of the following is the composition of the fetal membrane when there is twin pregnancy?
a) 2 amnions, 1 chorion
b) 1 amnion, 1 chorion
c) 1 amnion, 2 chorions
All are possible.
this structure extends from the fetal umbilicus to the fetal surface of the placenta or chorionic plate
Umbilical cord
average length of the umbilical cord
55cm
average diameter of the umbilical cord
0.6-2.0 cm
the extra cellular matrix of the umbilical cord is called the
wharton’s jelly
the umbilical cord is composed of what 3 main vessels?
2 umbilical arteries
1 umbilical vein
the oxygenated blood form the umbilical vein empties into the IVC via what fetal bypass?
Ductus venosus
true or false. both Placenta and trophoblast cells are endocrine organs
true
earliest hormonal signal for pregnancy
human chorionic gonadotropin (HCG)
when is HCG detected in the maternal circulation?
8-9 days post ovulation
hcg ca be synthesized by the kidney. T/F.
True
the doubling time of hCG
1.7-2 days
what are the characteristics of the subunits of hCG:
a) alpha
b) Beta
Alpha: shared with LH, TSH and FSH
Beta: unique thus it is the one being detected
when does hCG reaches its peak concentration?
@ 10 weeks (50000-100000 mIU/mL)
*responsible for vomiting
hCG is secreted by what cells and produced by what cells?
Produced by: Trophoblasts
Secreted by: Syncytiotrophoblasts
*before 5 weeks, it is secreted by both Cyto and Syncytio
when does hCG becomes (+) for PT?
at 5 weeks
Biological functions of the hCG
stimulates fetal testis
stimulates maternal thyroid activity
rescues the corpus lutem
promotes uterine vasculature VD, relaxin scretion by corpus luteum
a high hCG level may mean that:
there is multiple pregnancy
GTD (gestational trophoblastic disease)
ex: H.mole/chorecarcinoma
what are the functions of the human placental lactogen (hPL)
Anti-insulin (+) maternal lipolysis Angiogenic hormone ensure nutrient supply to the fetus Tumor marker
relaxin can be secreted by?
Corpus luteum
Decidua
Placenta
serves as the parathyroid of fetus
Parathyroid hormone-related protein
aka placental growth homone
Growth hormone variant (hGH-V)
stimulates the secretion of hCG
GnRH
when does the placenta assume progesterone secretion?
at 8th week
little progesterone is secreted by the ovary after?
after 6-7 weeks of gestation
surgical removal of the corpus luteum at 7th-10th week is extremely lethal for pregnancy. T/F
False. at 8th week, the placenta assumes progesterone secretion
what is the substrate for progsterone
Cholesterol
hormone that provides placental quiescence
progesterone
production of both progesterone and estrogen in the maternal ovaries decreases significantly by the 7th week. at this time placenta will assume progesterone secretion around the 8th week. this is called the?
Luteal-Placental Transition
