Spermatogenesis
Spermatogenesis
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Seminiferous tubule with maturing sperm. H&E stain.
Spermatogenesis is the process by which male primordial germ cells called spermatogonia undergo meiosis, and produce a number of cells termed spermatozoa. The initial cells in this pathway are called primary spermatocytes. The primary spermatocyte divides into two secondary spermatocytes; each secondary spermatocyte then divides into two spermatids. These develop into mature spermatozoa, also known as sperm cells. Thus, the primary spermatocyte gives rise to two cells, the secondary spermatocytes, and the two secondary spermatocytes by their subdivision produce four spermatozoa.[1]
Spermatozoa are the mature male gametes in many sexually reproducing organisms. Thus, spermatogenesis is the male version of gametogenesis. In mammals it occurs in the male testes and epididymis in a stepwise fashion, and for humans takes approximately 64 days.[2] Spermatogenesis is highly dependent upon optimal conditions for the process to occur correctly, and is essential for sexual reproduction. DNA methylation and histone modification have been implicated in the regulation of this process.[3] It starts at puberty and usually continues uninterrupted until death, although a slight decrease can be discerned in the quantity of produced sperm with increase in age (see Male infertility).
A mature human Spermatozoon Contents * 1 Purpose * 2 Location * 3 Stages * 3.1 Spermatocytogenesis * 3.2 Spermatidogenesis * 3.3 Spermiogenesis * 4 Role of Sertoli cells * 5 Influencing factors * 6 Hormonal control * 7 See also * 8 References * 9 External links |
Purpose
Spermatogenesis produces mature male gametes, commonly called sperm but specifically known as spermatozoa, which are able to fertilize the counterpart female gamete, the oocyte, during conception to produce a single-celled individual known as a zygote. This is the
From Wikipedia, the free encyclopedia
Jump to: navigation, search
Seminiferous tubule with maturing sperm. H&E stain.
Spermatogenesis is the process by which male primordial germ cells called spermatogonia undergo meiosis, and produce a number of cells termed spermatozoa. The initial cells in this pathway are called primary spermatocytes. The primary spermatocyte divides into two secondary spermatocytes; each secondary spermatocyte then divides into two spermatids. These develop into mature spermatozoa, also known as sperm cells. Thus, the primary spermatocyte gives rise to two cells, the secondary spermatocytes, and the two secondary spermatocytes by their subdivision produce four spermatozoa.[1]
Spermatozoa are the mature male gametes in many sexually reproducing organisms. Thus, spermatogenesis is the male version of gametogenesis. In mammals it occurs in the male testes and epididymis in a stepwise fashion, and for humans takes approximately 64 days.[2] Spermatogenesis is highly dependent upon optimal conditions for the process to occur correctly, and is essential for sexual reproduction. DNA methylation and histone modification have been implicated in the regulation of this process.[3] It starts at puberty and usually continues uninterrupted until death, although a slight decrease can be discerned in the quantity of produced sperm with increase in age (see Male infertility).
A mature human Spermatozoon Contents * 1 Purpose * 2 Location * 3 Stages * 3.1 Spermatocytogenesis * 3.2 Spermatidogenesis * 3.3 Spermiogenesis * 4 Role of Sertoli cells * 5 Influencing factors * 6 Hormonal control * 7 See also * 8 References * 9 External links |
Purpose
Spermatogenesis produces mature male gametes, commonly called sperm but specifically known as spermatozoa, which are able to fertilize the counterpart female gamete, the oocyte, during conception to produce a single-celled individual known as a zygote. This is the
References: 2. ^ Heller, C.G.; Clermont, Y. (April 1963). "Spermatogenesis in Man: An Estimate of Its Duration". Science 140 (3563): 184–6. doi:10.1126/science.140.3563.184. PMID 13953583. 4. ^ The Production of Spermatogenesis from ncbi.nlm.nih.gov. Retrieved August 15, 2012. 5. ^ a b Xiao, X.; Mruk, D. D.; Cheng, C. Y. (2013). "Intercellular adhesion molecules (ICAMs) and spermatogenesis". Human Reproduction Update 19 (2): 167–186. doi:10.1093/humupd/dms049. PMC 3576004. PMID 23287428. edit 6 7. ^ Lewis SE, Aitken RJ (2005). DNA damage to spermatozoa has impacts on fertilization and pregnancy. Cell Tissue Res 322(1):33-41. Review. PMID: 15912407 8 * "The testes and spermatogenesis". University of Wisconsin. 1998. Archived from the original on 2006-11-10. Retrieved 2006-11-27. * Johnson, L; Blanchard, TL; Varner, DD; Scrutchfield, WL (1997). "Factors affecting spermatogenesis in the stallion". Theriogenology 48 (7): 1199–1216. doi:10.1016/S0093-691X(97)00353-1. PMID 16728209. * Bardin, C.W. (1991). "Pituitary-testicular axis". In Yen, S.S.C.; Jaffee, R.B. Reproductive Endocrinology (3rd ed.). Philadelphia: WB Saunders. ISBN 0721632068. * Chambers CV, Shafer MA, Adger H, et al. (February 1987). "Microflora of the urethra in adolescent boys: relationships to sexual activity and nongonococcal urethritis". J. Pediatr. 110 (2): 314–21. PMID 3100755. * Czyba, J.C.; Girod, C. (1980). "Development of normal testis". In Hafez, E.S.E. Descended and Cryptorchid Testis. The Hague: Martinus Nijhoff. ISBN 9024723337. * Whitmore WF, Karsh L, Gittes RF (October 1985). "The role of germinal epithelium and spermatogenesis in the privileged survival of intratesticular grafts". J. Urol. 134 (4): 782–6. PMID 2863395.