[Early embryo death: does the male factor play a role?]

To discuss the possible role of the male factor in early embryo death.

A detailed bibliographic review has been put together to establish which alterations in spermatozoa can be associated with early embryo death.

Before the fusion between plasma membranes of the sperm and the oocyte occurs, both germ cells must undergo a maturation process that allows successful fertilization and embryo development. The study of couples with early embryo loss is usually approached from the side of the woman due to the obvious relationship that exists between the female and the developing embryo. However, it is not illogical to suppose that a genetic or epigenetic alteration of the sperm could have important consequences on these losses due to the necessary contribution of the male gamete not only to embryonic but also to placental development. On the other hand, spermatozoa have certain characteristics such as a highly compact DNA, they undergo apoptosis and the seminal plasma contains antioxidants that protect the structural and functional integrity of the germ cell. These factors assure fertilization and embryo development. Nevertheless, epigenetic alterations of the sperm such as altered chromatin packing, mistakes in imprinting, absence or alteration of the centrosome, telomeric shortening and absence of sperm RNA, could affect functions leading to early embryo loss.

Knowledge concerning sperm intervention previous to embryo development will provide the basis for better understanding and for possible diagnosis and treatment of diverse reproductive alterations in men that could impede embryo development.