US EPA

7432997 

Journal Article 

Defective Spermatogenesis and Sperm DNA Damage 

Sharma, R; Agarwal, A; , 

2018 

Springer International Publishing 

Cham 

A Clinician's Guide to Sperm DNA and Chromatin Damage 

229-261 

10.1007/978-3-319-71815-6_14 

http://link.springer.com/10.1007/978-3-319-71815-6_14
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Spermatogenesis is a highly complex temporal event during which relatively undifferentiated diploid cells called spermatogonia slowly evolve into highly specialized haploid cells called spermatozoa. The goal of spermatogenesis is to produce a genetically unique male gamete that can fertilize an ovum and produce offspring. Spermatogenesis is initiated through the neurological axis by the hypothalamus, which releases gonadotropin-releasing hormone (GnRH), which in turn signals follicle-stimulating hormone (FSH) and luteinizing hormone (LH) to be transmitted to the reproductive tract. Spermatogenesis involves a series of cell phases and divisions by which the diploid spermatogonial cells develop into primary spermatocytes via mitosis. Primary spermatocytes in the basal compartment of the seminiferous tubules undergo meiotic divisions to produce haploid secondary spermatocytes in the adluminal compartment in a process called spermatocytogenesis. After spermatocytogenesis, spermatids elongate to form spermatozoa by the process of spermiogenesis, a morphological development phase in which the nuclear transformations involving chromatin remodeling and compaction occur. Finally, spermatozoa are released from the Sertoli cells into the lumen of the seminiferous tubules in a process called spermiation and enter the epididymis for final maturation. Spermatogenesis in the human male takes about 74 days, while the process of epididymal maturation takes an additional 14 days. In the following sections, the complex transformation of the simple single diploid cell into a fully functional haploid cell is described. Furthermore, events associated with defective spermatogenesis and DNA fragmentation are highlighted, and mechanisms to repair DNA fragmentation are described in this chapter.