Within each testicle contain spermatogonia cells which produce sperm
After numerous cell divisions. First they divide to produce primary spermatocytes retaining all chromosomomes (mitosis), these divide into secondary spermatocytes & 1/2 no. Of chromosomes, divide again, then again to form 4 spermatids each of which matures into sperm. They pass thru tubules, then epididymis into vas daferens.