Question

why does the thymus reduce in size at the attainment of puberty?

Answer 1

The thymus reduces in size because of the increase in circulation of sex hormones, at the start of puberty. This is called thymic involution.

Answer 2

well,i do knw tat and hence the question,wat i mean to ask is why does the increase in circulation of sex hormones cause the reduction in the size of the thymus? what is the necessity ? what role does the thymus play other than being a secondary lymphoid organ?

Answer 3

That's a good question. As far as I know, it's a mystery why thymic involution happens, even though no clear benefits can be seen.

Some scientists have proposed hypotheses as to why it happens. One hypothesis states that when our T cells react strongly to antigens that we produce ourselves, our bodies try to eliminate these T cells. That's because we don't want our bodies to go into an auto-immune response. Those T cells need to be eliminated.

But when these T cells are eliminated, we end up with a shortage of T cells that can respond to foreign antigens. That's a problem, yes? So, our body's solution is to have the thymus produce as many T cells as it can, while we are still very young, and in the womb. And then the thymus begins to involute, because it has already done most of its job. Yes, according to this hypothesis, the thymus actually begins to involute very early on in life. As early as the first year. And the pace really picks up at around puberty.

And again, the reason it does most of its job so early is because it "knows" that later on, the body's T cells will inevitably be destroyed, to prevent an autoimmune response.

This hypothesis is evolutionary. As far as I know, nobody has been able to make a theory out of it.

Answer 4

yea,it sounds more of evolutionary type! the body destroys it's own T cells? if u can cud u plzz elaborate on tat!
thanks,u have been a gud help!