Transcript Pregnancy and the Placenta

Pregnancy and the Placenta
Robert Scranton ©2009
Fertilization
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Sperm Ascends aided by:
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Normal Site of Maturation
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Uterine tube contractility
Sperm motility
Ampulla of the oviduct
Sperm Matures
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Capacitation
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Removal/ alteration of stabilizing proteins and/ or protective coat
Acrosome Reaction
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Recognization of ZP3 receptors fusion of acrosomal & cell
membranes then release of acrosomal enzymes
Fertilization
•Sperm penetrates the Corona
Radiata, zona pellucida and oocyte
cell membrane
•Cortical Reaction
Definitions
Sperm cell nucleus enters=male pronucleus
2° oocyte completes
maturation division
Female Pronucleus
Its Diploid Again!
How many cells? 16
Inner cell mass (embryoblast= future embryo)
Outer cell mass (trophoblast= fetal contribution
to placenta
Blastocyst/ Blastocoele
Attaches at embryonic pole
Where would an abembryonic pole be?
Trophoblast
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What does the trophoblast secrete?
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When is the hCG detectible in the maternal urine?
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hCG- human chorionic gonadotrophin, a luteinizing hormone
Around 14 Days after conception (was in circulation 6-8 days
post conception)
They divide mitotically, what is special about how they
divide?
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Outer layer doesn’t undergo cytokinesis so a syncytium is
formed
Remember the definition of a syncytium?
Syncytiocytotrophoblast
(syncytiotrophoblast)
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Multinucleated layer of cytoplasm providing a continuous
source of hCG and other hormones
Cytotrophoblast
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Layers of trophoblast cells, each with a single nucleus,
miosis produces additional cytotrophoblasts
What lines the amniotic cavity?
Amnioblasts + Ectoderm
Extraembryonic
mesenchyme
Migrating
endoderm cells
along Heuser’s
Membrane
AKA Chorionic Cavity
Future
umbilical cord
Somatic
Splanchnic
Primary Villi= cytotrophoblast projecting into synctiotrophoblast
Cytotrophoblasts
Synctiotrophoblast
Mesoderm
Fetal Blood Vessels
Secondary Villi= add mesoderm
Cytotrophoblasts
Synctiotrophoblast
Mesoderm
Fetal Blood Vessels
Tertiary Villi= add fetal blood vessels
Cytotrophoblasts
Synctiotrophoblast
Mesoderm
Fetal Blood Vessels
What was he trying to get across with this?
Arias-Stella phenomenon
Purely a descriptive term applied to the gravid, hypersecretory, uterus
•Endometrial cells:
•Plump
•Eosinophilic
•Endometrial glands:
•Hyperchromatic
•Enlarged nuclei
•Cytoplasmic vacoules
Definition: Syncytiptrophoblast Lacuna
OR
Why is it that we can deliver the baby and
placenta and the mother doesn’t exsanguate
(bleed-out)?
Cotyledon- arteriolar BP raising the basal plate
Decidua
(endometrial tissue)
Basalis
Capsularis
Parietalis
Transport
• Rapid Diffusion
• oxygen, carbon dioxide, urea, electrolytes
•Facilitated Diffusion
•Glucose, AAs, thyroxine, alcohol, morphine
•Slow Diffusion
•Fat soluble vitamins, steroids
•Endocytosis
•Antibodies, viruses, gamma globulins
Hormones
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hCG
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Major (indirect) effect on development of male genetalia
(stimulates fetal Leydig cells)
Maintains corpus luteum
Alterations:
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Low in 1st trimester
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Failing placenta
High in 2nd or 3rd
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Molar pregnancy (trophoblastic disease)
hCS- human chorionic
sommatomammotrophin
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Like GH and PRL
Regulates late-gestation fatty acid/ carb. metabolism
Progesterone
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Produced by:
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1st trimester
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2nd & 3rd trimester
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Corpus luteum
Placenta
Purpose
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Maint. Of pregnancy
Breast/ glandular development
Decidualization of endometrium
Prevention of coordinated uterine SM contraction
Estrogen (E2) and Estriol (E3)
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E2- from corpus luteum then placenta; same 1-2/3 split
E3- 3-step production process from placenta to fetal
adrenal cortex to placenta…
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since its production is complicated, requiring both placenta and
fetus, it can be used as an index of a normally functioning
placenta and fetus
The Cord!
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Two arteries spiral around one vein
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If its different, its associated w/ disease (maternal diabetes, CV
and UG symptoms…. Also death)
Wharton’s Jelly
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The mesenchyme (remember the “splanchnic mesoderm”
covering the cord?)
Name calling:
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40 weeks- Menstrual Age
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38 weeks- Gestational Age
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Delivery is 38 weeks after ovulation/ conception
Embryo
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Delivered 40 weeks after FIRST DAY OF LAST MENSTRUAL
PERIOD (beginning of menstruation)
First 8 weeks, where teratogenic effects happen (most of the
time; remember Fetal alcohol syndrome and 14 days to home
urine pregnancy test)
Fetus
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Week 9 to delivery
Name calling
Abortion/ miscarriage
Premature
Term
Post-term
L&D
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3 stages
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1- dilate (due to uterine contractions) 10cm
2- deliver infant
3- deliver placenta
Regulation
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Oxytocin
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Progesterone w/draw
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Inhibits oxytocin- so problem with progesterone production could lead to
premature labor
CRH stimulation
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Myometrial contraction
Stimulates prostaglandin release
Stimulates fetal Hypothalamic-Pituitary axis cortisol increase to develop lungs,
GI tract, and cerebral vasculature
Prostaglandin Stimulation
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(from amnion and decidual cells) stimulate myometrial contraction and cervical
dilation & effacement…. Initiate labor
Review Gross Anatomy of the Placenta on Med Micro