Question
Fetal response to the micro-organism shown in the electron microscopy image below occurs at which week of pregnancy?
A. 4th week.
B. 8th week.
C. 18th week.
D. 28th week.
Show Answer
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Correct Answer » C Explanation |
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Ans:C. 18 weeks.
The micro-organism as represented by an electron microscopy image above is Treponema pallidum.
Treponema pallidum.
- It is a spirochaete bacterium
- Using light microscopy, treponemes are visible only by using dark field illumination.
- They are helically coiled, corkscrew-shaped,Gram negative, but some regard them as too thin to be Gram stained.
- The risk of fetal infection depends on the degree of maternal spirochetemia (greater in the secondary stage than in the primary or latent stages) and the gestational age of the fetus.
- Treponemes may cross the placenta at all stages of pregnancy, but fetal involvement is rare before 18 weeks.
- After 18 weeks, the fetus is able to mount an immunologic response, and tissue damage may result.
- The earlier in pregnancy the fetus is exposed, the more severe the fetal infection and the greater the risk of premature delivery or stillbirth.