Ob1(lec1) Placenta

OB Lecture 1 - PLACENTA AND PLACENTAL HORMONES USTMED ’07 Sec C - AsM

Posterofundal (upper 1/3) of uterus – implantation of blastocyst Called morulla while in fallopian tube Called blastocyst in the uterus Called endometrium in the non-pregnant state Called decidua in pregnant state Trophoblast – cells surrounding blastocyst Chorion frondosum – cells surrounding blastocyst; tree-like projections; protrusions from trphoblast Avascular trophoblast – due to expansion of amniotic cavity (?) 1. 2.

placental arm – villi, trophoblast and fetal & maternal blood present paracrine arm – membrane coverings a. chorion - avascular b. amnion - avascular c. deciduas – vascular

Decidua Vera (DV) = DC + DP Amnion membrane that contains A.F. (1L) - > ____ = diabetic - <500 mL = renal system failure -

avascular membrane solute & water transport to maintain AF homeostasis produces endothelin-1 – causes vasoconstriction – decreases blood flow produces parathyroid hormone related protein produces enkephalinase modulates chorionic vessel tone and blood flow

Placenta provides insight into prenatal life helpful in caring for neonate plan future care for mother/child Trophoblast attachment of blastocyst to the uterus nutrition endocrine function Trophoblast – producer of Human Chorionic Gonadotropins (HGC) 1. cytotrophoblast germinal cell cAMP on FM (?) 1. trohpoutronectin Trophoblast 2. trophoblastic glue 3. facilitates separation of tissue at delivery 2. syncitiontrophoblast secretory cell Umbilical cord = 2 arteries + 1 vein (fetus can survive with only 1 artery fetal blood (deO2 blood) enter chorionic plate then passes to the chorionic villi approx 50 cms (longer – might strangulate baby; or shorter – tug on placenta = death) covered by wharton’s jelly Factors Regulating Blood Flow BP (hypotensive – due to bleeding, etc.) Intrauterine pressure Type of uterine contractions Factors affecting arteriolar walls (endothelin-1 – vasoconstrictor)

Fetal Surface shiny and glistening course of vessels = chorionic vessels – branches of umbilical arteries attachment of umbilical cord central or paracentral only (not in periphery coz the amount of blood going to umbilical vein will lessen therefore less nutrition, O2 and perfusion) Maternal Surface - attachment of cotyledons - rough Placental aging decrease of syncitial thickness loss of Langhan’s cells Fibrin deposits obliteration of blood vessel villi thickened basement membrane increased capilliaries decrease stroma - * abnormal placenta - vesicular/grape-like tissue - contains water

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Hydatidifor m mole

Decrease Estrogen Fetal anencephaly maternal adrenal dysfunction materal ovarian androgen producing tumors placental sulfatase deficiency decrease fetal adrenal utilization of LDL deficiency in fetal LDL synthesis glucocorticoid treatment placental aromatase deficiency Placental Hormone – Progesterone syncitiontrophoblast utilization of maternal LDL Cholesterol Cytochrome P450

Pregnenolone 3B Hydroxysteroid dehydrogenase isomerase

Placental Hormone – HCG syncitiotrophoblast alpha and beta subunits structurally related to LH, FSH and TSH Alpha sub-units identical Beta sub-units are distinct HCG Beta sub-unit is the basis for pregnancy kit increase bet 9-10 wks of AOG amt is directly related to no. of trophoblast doubles every 2 days Fcn: • rescue and maintains corpus luteum • stimulate Leydig cells of the fetal testes • induces ovulation (infertile women) increase HCG • multiple pregnancies • fetal hydrops • H-mole • choriocarcinoma

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detected on 2nd or 3rd week of fertilization structurally related to human growth hormone and human prolactin gestational diabetes – because HPL has anti-insulin effect

Metabolic Actions of HPL

7th week >50% placenta precursors o DHEA o Androstenedione o Testosterone

Progesterone

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HPL synthesis stimulated by insulin Inhibited by PGE2 and PGF 2 alpha greatest hormone in humans present w/in 5-10 days after conception proportional to placental mass concentration rises until 34-36 wks AOG

Placental Hormones – Estrogen pregnancy is hyperestrogenic state syncitiontrophoblast ovaries 2-4 wks post-ovulation

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Placental Hormone – Human Placental Lactogen (HPL) chorionic somatotropin chorionic growth hormone syncitiotrophoblast

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lipolysis and increase circulating free fatty acids (baby therefore does not starve) anti-insulin incrase maternal insulin CHON synthesis a.a. for transport of fetus

HPL is increased in bronchogenic carcinoma hepatoma lymphoma pheochromocytoma

- fin AsM