Why are the fetus and placenta, which resemble an allograft in that they express paternal genes, not rejected by the mother? Paradoxically, the fetus survives pregnancy despite the laws of classical transplantation immunology.

The placenta forms a barrier between the fetus and the mother; it's not exposed to the other immune system.

That was a short one

 

Is this barrier similar in any way to the brain barrier?

Only similar in the fact it suspends the brain in a fluid medium also... protects it from damage.

The barrier does not protect against different RH factors in the blood. This could potentialy kill the child or the mother.

Just aman

That's an exception to the rule. But for example if the mother has HIV, the child will not necessarily get it (and if it does, transmission occurs during birth).

Blike was asking about fetal rejection and I can't think of any other instance but the RH+ and RH- difference. My Dad was B+ and my Mom was A+ and I'm AB+ and it didn't affect my Mother or me because of the barrier.

I don't have any idea how common the RH difference is or really how serious the problem can be. You would think that we would have evolved to absorb the defective fetus early rather than kill the mother. It seems the body does not recognize even some pretty extreme genetic differences in the womb and will carry to term. We seem to be a very resilient race.

Just aman

well this is a view from langhmans......

 

the immunology of pregnant lady is suppressed and so the rejection doesnt occur......

 

any contras...

Well, wouldn't pregnant women be dropping like flies with such a lowered immunity?