Female Histology 5

Question 1

What is the role of the placenta?

Answer 1

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

Question 2

Describe the makeup and histology of the umbilical cord.

Answer 2

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

Question 3

Describe the histology of the chorionic villous.

Answer 3

• 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

Question 4

Describe the histology of the decidua basalis.

Answer 4

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

Question 5

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

Answer 5

• 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