Saturday, March 24, 2012

PLACENTA AND FETAL MEMBRANES



PLACENTA
  • Development
  • Gross anatomy
  • Structures
  • Functions
  • Abnormalities

DEVELOPMENT

1.Chorionic frondosum- fetal part the major component
2.Decidua basalis- maternal part the minor component

Begins at 6th weeks of gestation
Ends at 12th weeks of gestation

Anatomy
  • Normally situated at or near fundus of uterus
  • Shape- discoid
  • Size- 15*20 cms, 2.5cm in thickness in centre
  • 500gms in weight
  • Two surfaces

1.Fetal- smooth, amniotic membrane, cord insertion and branching vessels.
2.Maternal- irregular,15-20 cotyledons,

Fetal surface

Maternal surface


Structure




Functions
  1. Nutrition
  2. Respiration
  3. Excretion
  4. Barrier
  5. Hormonal- CRH, GnRH, TRH, GHRH, ACTH, hCG, hPL, hCT
  6. Immunological- placental hormones, proteins(SP1), early pregnancy factor(EPF), steroids and hCG

Abnormal placenta

One or more smaller lobes of placenta placed at varying distances from placental margin.

Smaller chorionic plate than basal plate.


Cord Abnormalities

The cord is attached to the membranes.

The cord is attached to the margin of the placenta.



FETAL MEMBRANES
  • CONSISTS OF 2 LAYERS

CHORION

AMNION

FUNCTIONS OF MEMBRANES

1.PRODUCES AMNIOTIC FLUID

2.PREVENTS FETUS FROM INFECTIONS

3.HELPS IN CERVICAL DILATION IN LABOR

4.PRODUCES PGE2, PGF2alpha

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