Re: What cells in the body do spermatozoa come from

Sperm cells are derived from a specific "stem cell" type that is located only in the testis.  These cells give rise 
to spermatogonial cells, which then divide (see http://www.mcb.arizona.edu/Wardlab/
buddingvid.html) to give rise primary spermatocytes.  

Once mitotic division are completely, these cells  undergo meiosis to give rise to spermatids.  
Each spermatid matures into a sperm cell.  The cells of the testis (and the ovary) are specialized 
"germ" cells which are set aside from the rest of the cells of your body (somatic cells) early in development.  

When you get a transfusion, you receive only somatic cells (in fact these cells that have withdrawn from 
active cell division and are destined to die in a relatively short time).  

There is NO possibility that these cells will have ANY influence WHAT SO EVER on the genetic make 
up of your children!   

(image of spermatocytes from http://zygote.swarthmore.edu/germ7.html)