Zygotic chromosomal structural aberrations after paternal drug treatment

Abstract

In recent years, the field of male-mediated reproductive toxicology has received growing attention. It is now well-established that many drugs, chemicals, and environmental factors can harm male germ cells by inducing DNA damage. Male germ cells have extensive repair mechanisms that allow detection and repair of damaged DNA during the early phases of spermatogenesis. However, during the later phase of spermiogenesis, when the haploid spermatids undergo chromatin condensation and become transcriptionally quiescent, their ability to repair damaged DNA is lost.12 It is also thought that the highly compacted chromatin of the sperm can protect DNA against damage.3 Therefore, it is expected that late spermatids will be most susceptible to DNA damaging agents. Unrepaired or misrepaired damage in the germ cells leads to the generation of spermatozoa with DNA damage that can be transmitted to the next generation. Fortunately, the maternal DNA repair machinery is capable of recognizing and repairing, at least to some degree, damaged paternal DNA after fertilization in the zygote. Therefore, the efficiency of the maternal repair machinery will greatly influence the risk of transmitting paternal DNA damage to offspring.4

Interspecific ICSI for the Assessment of Sperm DNA Damage: Technology Report

“…Indeed, it has been demonstrated that immotile and even dead spermatozoa, for example, when lyophilized or recovered from frozen cadavers, can produce normal offspring when injected into the same species oocyte [ 3 , 4 ]. On the other hand, the motile spermatozoa with damaged DNA (i.e., after chemotherapy) can fertilize the oocyte but subsequent development is compromised [ 5 ]. Typically, these spermatozoa decondense in the cytoplasm and form pronuclei with delayed DNA replication; further cleavage is abnormal, and micronuclei can be detected in the cytoplasm of the two-cell embryos [ 6 , 7 ].…”