Female Histology 5 Flashcards

Describe the origin and structure of a placental villus and placental membrane (maternal/fetal blood barrier).

1
Q

What is the role of the placenta?

A
  • physiological exchange between mother and fetus
  • also an endocrine organ:
    • HCG
    • estrogens
    • progesterone
    • renin
    • human placental lactogen (HPL)
    • thyroptropic substance
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2
Q

Describe the makeup and histology of the umbilical cord.

A
  • mucous connective tissue
  • connects placenta to fetus
  • contains two umbilical arteries (deoxygenated blood)
  • umbilical vein (oxygenated blood)
  • yolk sac
  • allantois
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3
Q

Describe the histology of the chorionic villous.

A
  • Fetal part of placenta
  • branching structure composed of the three layers of the blastocyst chorion
    • outer syncytiotrophoblast
      • endocrine layer in contact with maternal blood
      • manufactures and secretes HCG
    • cytotrophoblast - mostly disappears during late pregnancy
    • mesodermal core - extra-embryonic
      • forms connective tissue in which fetal vessels develop
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4
Q

Describe the histology of the decidua basalis.

A
  • maternal part of the placenta
  • contain blood vessels which upen into lacunae surrounding fetal villi
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5
Q

Describe the histology of the placental membrane (maternal-fetal blood barrier).

A
  • Sequential layers:
    • syncytiotrophoblast
    • cytotrophoblast (when present)
    • basal lamina of cytotrophoblast
    • mesenchyme of the villus
    • basal lamina of fetal capillaries
    • endothelium of fetal capillaries
  • late in pregnancy the membrane thins as the cytotrophoblast disappears and the two basal laminae fuse as the capillaries press against the syncytiotrophoblast
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