**Abstract**

Sperm genome condensation is mainly important as the genome expression should be repressed until it is fertilised with oocyte. In most of the mammals, protamines play an important role in genome condensation. In humans, histone variants were present in germ cells when compared with somatic cells. How successful replacement of histones by protamines occurs in most of the mammals is an interesting question. Little information is known about transition proteins that replace histones with protamines. Apart from condensation, which mechanisms prevent expression of X and Y chromosomes in sperm is to be studied. If exposed to genotoxic agents like Metosartan that damage testes should also be considered, in order for assisted reproductive technologies like in vitro fertilisation to succeed.

**Keywords:** assisted reproductive technology (ART), intra cytoplasmic sperm injection (ICSI), invitro fertilisation (IVF), stem cell factor (SCF), protein dependent kinase (PDK), glial cell derived neurotropic factor (GDNF), post translational modification (PTM), chromatin assembly factor (CAF), testes specific serine/ threonine kinase 6 (TSSK6), nucleolar organising region (NOR), p- element induced wlmphy testes in drosophila (PIWI), a disintegrin and metalloprotease (ADAM)
