Spermatogenesis, DNA damage and DNA repair mechanisms in male infertility  Sezgin Gunes, Maha Al-Sadaan, Ashok Agarwal  Reproductive BioMedicine Online  Volume 31, Issue 3, Pages 309-319 (September 2015) DOI: 10.1016/j.rbmo.2015.06.010 Copyright © 2015 Reproductive Healthcare Ltd. Terms and Conditions

Figure 1 DNA replication fork. A view of the arrangement of the replication proteins at the replication fork is shown. Several enzymes and proteins are involved in replication process of genome. Accurate duplication of genetic material is important for both somatic and germ cells and is carried out by polymerase enzymes. SSBP = single-stranded DNA-binding proteins. Reprinted with permission, Cleveland Clinic Center for Medical Art & Photography © 2014. All Rights Reserved. Reproductive BioMedicine Online 2015 31, 309-319DOI: (10.1016/j.rbmo.2015.06.010) Copyright © 2015 Reproductive Healthcare Ltd. Terms and Conditions

Figure 2 Spermatogenesis. Primordial germ cells, proliferative type A spermatogonia, undergo a series of mitotic divisions. One of the daughter cells renews the stock of type A spermatogonia, the other becomes a type B spermatogonia with incomplete cytoplasmic separation. These divide and their daughter cells migrate towards the lumen. Type B spermatogonial cells enter the meiotic pathway. Meiosis involves two cell divisions to produce haploid spermatids with only one round of DNA synthesis. Finally, spermatids differentiate into spermatozoa and are released into the lumen of tubule. Reprinted with permission, Cleveland Clinic Center for Medical Art & Photography © 2014. All Rights Reserved. Reproductive BioMedicine Online 2015 31, 309-319DOI: (10.1016/j.rbmo.2015.06.010) Copyright © 2015 Reproductive Healthcare Ltd. Terms and Conditions

Figure 3 DNA damage and DNA repair mechanisms. Common DNA damaging agents (left), DNA lesion induced by these agents (middle), and the most relevant DNA repair mechanisms responsible for the removal of the lesions (right). Reprinted with permission, Cleveland Clinic Center for Medical Art & Photography © 2014. All Rights Reserved. Reproductive BioMedicine Online 2015 31, 309-319DOI: (10.1016/j.rbmo.2015.06.010) Copyright © 2015 Reproductive Healthcare Ltd. Terms and Conditions