Implantation and Fetal Membranes Flashcards Preview

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Flashcards in Implantation and Fetal Membranes Deck (27):

describe what the enzyme vesiculase does

  • coagulates semen to form a plug at the externa os which prevents backflow of semen into the vagina


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implantation of ____ begins on day ____ and ends on day _____

implantation of blastocyst begins on day 5/6 and ends on day 10


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1 = endometrium

2 = hypoblast

3. synctiotrophoblast

4 = cytotrophoblast

5 = epiblast


the usual site of implantation is....

the usual site of implantation is the posterior wall of body of uterus close to the fundus


name 2 enzymes the synctiotrophoblast secretes

  1. proteolytic enzymes to erode endometrium and blastocyst burrows into endometrial CT
  2. also secretes hCG which maintains the corpus luteum


describe pregnancy tests

  • tests for hCG in maternal urine at end of 2nd week after conception
  • test for presence of early pregnancy factor (EPF), an immunosuppressant protein which appears in maternal serum 24-48 hours after conception


equation for calculating expected date of delivery (EDD)

Date of last menstrual period + 9 months + 7 days (Naegele's rule)


describe Hydatiform mole (H-mole)

  • A molar pregnancy starts when an egg is fertilized, but instead of a normal, viable pregnancy resulting, the placenta develops into an abnormal mass of cysts.
  • little to no embryonic tissue present
  • trophoblast develops well
  • hCG produced
  • may give rise to choriocarcinoma


describe the primary yolk sac or exocoelomic cavity

  • first site of blood formation
  • gives rise to the primordial gut
  • primordial germ cells arise in the endodermal lining of the yolk sac


describe the allantois

  • arises as a diverticulum from the yolk sac and extends into the body stalk
  • another early site of blood formation
    • its blood vessels form the umbilical arteries and veins
  • obliterates and forms the urachus (median umbilical ligament postnatally)


describe the function of aminiotic fluid

  • shock absorber
  • maitains constant temp
  • lung development
  • symmetrical growth
  • antibacterial activity


the aminion fuses with ____ ____ and obliterates the _____ _____ forming the single ______ membrane

the aminion fuses with chorion wall and obliterates the chorionic cavity forming the single amniochorionic membrane


describe oligohydramnios and potential causes

  • low volume of amniotic fluid
  • causes:
    • preterm rupture of amniochorionic membrane
    • urinary system anomalies
      • renal agenesis
    • placental insufficiencies
      • decreased blood circulation
  • complications
    • lung hypoplasia
    • facial or limb deformities because less space to grow


describe polyhydramnios and causes

  • high amniotic fluid volume
  • causes:
    • idiopathic 
    • maternal 
      • multiple pregnancies
      • maternal diabetes
    • fetal
      • esophageal atresia
      • meroencephaly
      • anencephaly
  • complications
    • preterm labor and delivery


describe amniotic band syndrome

  • aminotic bands can amputate the limbs


describe the components of the chorion wall

  1. syncytiotrophoblast
  2. cytotrophoblast
  3. somatic layer of primary mesoderm


contast smooth chorion and villous chorion

  • smooth chorion = chorion sac enlarges toward the uterine cavity and the villi on that part degenerate
  • villous chorion = villi on the chorion sac towards the uterine wall grow and become bushy


name the 3 layers of the decidua

  1. decidua basalis is the endometrium deep to the chorion in contact with villous chorion
  2. decidua capsularis is the endometrium related to the smooth chorion and it separates it from the uterine cavity
  3. decidua parietalis refers to the rest of endometrium not directly related to the chorion sac


describe placental abnormalities

  • placenta accreta
    • abnormal adherence of placenta (chorionic villi) to the uterine wall
  • placenta percreta
    • placenta penetrates the entire uterine wall
    • 3rd trimester bleeding
  • placenta previa
    • placenta bridges the cervical opening
    • severe bleeding in later part of pregnancy


describe amniocentesis

  • sampling of the aminiotic fluid for karyotyping and levels of enzymes
  • performed in 2nd trimester
  • low relative risk 


describe chorionic villus sampling

  • biopsy of chorionic villi
  • can be performed as early as 7 weeks
  • detects chromosomal abnormalities, inborn errors of metabolism
  • riskier than amniocentesis


describe alpha-fetoprotein assays

  • glycoprotein synthesized in fetal liver and umbilical vesicle
  • increase: neural tube defects
  • decrease: Down syndrome


describe dizygotic twins

  • most common type
  • origin from 2 zygotes
  • fertilization of 2 oocytes by 2 sperms
  • 2 amnions and 2 chorions
  • placentas may be fused


describe monozygotic twins

  • origin from a single zygote
  • genetically identical and same sex
  • division of embryoblast into 2 embryonic primordia
  • 2 amniotic sacs
  • 1 chorionic sac
  • 1 placenta


describe twin transfusion syndrome

  • preferential shuting of arterial blood in one twin to venous blood in the other
    • donor twin = small and anemic
    • recipient twin = large and polycythemic


describe conjoint twins

  • incomplete division of the embryonic disc