BGDA Practical Placenta - Placental Functions: Difference between revisions

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<references/>
<references/>
===Placenta Measurements===
[[File:Placental volume graph.jpg|thumb|300px|Term Placenta Measurements]]
Morphometric indices at term of placental composition, villous capillarization and the mean cross-sectional areas of peripheral villi and capillaries.
{|
|-bgcolor="CEDFF2"
| width="150px"|'''Variable'''
| width="100px"|'''Unit'''
| width="100px"|'''Placenta'''
|-
|Intervillous space
| mL
| 213
|-bgcolor="F5FAFF"
| Stem villi
| mL
| 71.4
|-
| Peripheral villi
| mL
| 326
|-bgcolor="F5FAFF"
| Trophoblast
| mL
| 95.5
|-
| Stroma
| mL
| 184
|-bgcolor="F5FAFF"
| Fetal capillaries
| mL
| 46.9
|-
| Non-parenchyma
| mL
| 41.5
|-bgcolor="F5FAFF"
| Peripheral villi
| km
| 89.2
|-
| Fetal capillaries
| km
| 310
|-bgcolor="F5FAFF"
| TS area villi
| µm<sup>2</sup>
| 3700
|-
| TS area capillary
| µm<sup>2</sup>
| 150
|-bgcolor="F5FAFF"
| Capillaries
| mL mL<sup>-1</sup>
| 0.147
|-
| Length ratio
| km km<sup>-1</sup>
| 3.6
|-bgcolor="F5FAFF"
|}
Data from a study sample of 15 normal placenta, mean placental volume, 652 ml.<ref name=PMID18328557><pubmed>18328557</pubmed></ref><ref><pubmed>19141109</pubmed></ref>
{| class="wikitable collapsible collapsed"
! Measurement methodology
|-
|
* Microscopical fields on stained sections were selected by systematic uniform random sampling and analysed stereologically to estimate the volumes of placental compartments and total lengths of villi and fetal capillaries.
* Mean cross-sectional areas of peripheral villi and capillaries, together with measures of villous capillarization (capillary volume densities and capillary : villus length ratios), were derived from global volumes and lengths.
|}


===Drugs===
===Drugs===

Revision as of 11:04, 11 June 2013

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Practical 14: Implantation and Early Placentation | Villi Development | Maternal Decidua | Cord Development | Placental Functions | Diagnostic Techniques | Abnormalities


Term Placenta

Placenta term anatomy 01.jpg


Placenta Vasculature - MRI and CT

Term placenta viewed from the fetal side.[1]


Human placenta vascular MRI 02.jpg Human placenta vascular CT 01.jpg
Magnetic Resonance Angiography (MRA) Computed Tomography Angiography (CTA)
Legend
  • CA - chorionic artery
  • PSA - primary stem artery
  • SSA - secondary stem artery
  • TSA - tertiary stem artery

Exchange

Placenta oxygen exchange levels.jpg Placenta spiral artery conversion.jpg
  • oxygen, carbon dioxide, carbon monoxide
  • nutrients
    • water, glucose, vitamins
    • electrolytes
  • waste products
    • urea, uric acid, bilirubin.
  • hormones
    • mainly steroid, protein hormones poorly transported.
    • maternal thyroid hormone can slowly cross.
    • fetal insulin can impact on maternal diabetes.
  • maternal antibodies
    • maternal IgG antibodies are transferred from about week 13 (GA) across the placenta
    • from the maternal lacunae syncytiotrophoblast cell endosomes bind IgG through neonatal Fc receptors.
  • drugs and their metabolites
    • pre-existing maternal conditions
    • illegal drugs (fetal drug addiction)
  • infectious agents
    • cytomegalovirus, rubella, measles, malaria, listeria, microorganisms

Endocrine

Protein and steroid hormones.

  • Human chorionic gonadotrophin (hCG) - like leutenizing hormone, supports corpus luteum in ovary, pregnant state rather than menstrual, maternal urine in some pregnancy testing
  • Human chorionic somatommotropin (hCS) - or placental lactogen stimulate (maternal) mammary development
    • rise through pregnancy, stimulates maternal metabolic processes, breast growth
  • Human chorionic thyrotropin (hCT)
  • Human chorionic corticotropin (hCACTH)
  • Relaxin
  • Steroid Hormones - progesterone (maintains pregnancy), estrogens (fetal adrenal/placenta)

Placental Metabolism

Synthesises - glycogen, cholesterol, fatty acids

  • provides nutrient and energy


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Practical 14: Implantation and Early Placentation | Villi Development | Maternal Decidua | Cord Development | Placental Functions | Diagnostic Techniques | Abnormalities



Additional Information

Additional Information - Content shown under this heading is not part of the material covered in this class. It is provided for those students who would like to know about some concepts or current research in topics related to the current class page.


  1. ↑ <pubmed>20226038</pubmed>| BMC Physiol.

Drugs

  • Abnormal Development - Drugs - The placenta and fetal tissues may deal with drugs differently from adult target tissues. In particular, drugs are "cleared", metabolised and excreted, at a different rate in both the fetus and in newborn infants. In general there is a much lower rate of clearance.

<pubmed>21766440</pubmed> <pubmed>21789231</pubmed> <pubmed>19732616</pubmed>| PMC2767264


BGDsmall.jpg
Practical 14: Implantation and Early Placentation | Villi Development | Maternal Decidua | Cord Development | Placental Functions | Diagnostic Techniques | Abnormalities


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