What will happen to sperm if a man(transsexual) takesfemale hormone(estrogen)? does the sperm lose all functions? is that a barrier to be able to have a baby?

See below: If a male takes estrogen supplements, it will ultimately lower his sperm count and testosterone production. If taken long enough, his ability to regain sperm production and normal testosterone levels if he stops the estrogen may be ost as well.

Helpful Fact Sheet: See the fact sheet "reproductive options for trans people" from rainbowhealthontario.Ca specifically, check the section "fertility preservation for transpersons who produce sperm" here: http://bit.Ly/1axxbzq here's an excerpt: "testicular volume is greatly reduced by long-term estrogen use, impacting the maturation and motility of sperm." know your options for having a baby using your sperm.

Bank sperm: When I prescribe estrogen for my clients who are transitioning from male to female, I recommend that they bank sperm in advance. Taking estrogen tends to reduce erections and ejaculatory fluid. (Don't count on this for contraception, though!) I also recommend that clients who are transitioning to male consider egg harvesting in advance. Keeping options open is a good thing! LGromko MD