Sunday, 16 August 2020

Birth defects deepens on Timing of Exposure of toxic agent(environmental or drugs-alcohol ) & Type of Birth defect ?

 

Timing of Exposure & Type of Birth defect ?

The  susceptibility of the conceptus to teratogenic agents varies with the developmental stage at the time exposure. This concept of critical stages of developmental is particularly applicable to alterations in structure. It is during the second to the eighth weeks of development after conception – the embryonic period – that most structural defects occur. For such defects it is believed that there is a critical stage in the developmental process after which abnormal embryogenesis cannot be initiated.

 

NTD occurs when –at what period of gestation??

Ans Neural tube defects result from the failure of the neural tubes to close. Given that this process occurs between 22 and 28 days post conception any exogenous effect on development must be present at or before this time.

 

The neural tube has five distinct closure sites that may respond differentially to agents and may respond differently in timing. Investigation of thalidomide teratogenicity have clearly shown that effects of the drug differ as function of the developmental stage at which the pregnant woman took it.

No comments:

Post a Comment