Mast cells. Mast cells and basophils are generally thought to be the major sources of histamine and can themselves be modulated by histamine as they express H 1, H 2 and H 4 receptors, although how this varies between different mast-cell types is not yet clear.
3. The pill is to be taken soon after unprotected sex. It should be taken preferably within 24 hours and before 72 hours or else the pill may turn useless. 4. I-pill checks pregnancy by preventing ovulation or fertilisation or implantation of the fertilised egg. 5. I-pill is 95 per cent effective if taken in time.
If you had unprotected sex in the last 48 hours... There is a special morning after pill (also known as the Plan B pill) that you can take within the first 48 hours after having unprotected sex. The sooner you have it, the more chance that you won't have an unwanted pregnancy. It works by causing an early abortion if you are pregnant.