Editing Spermatocyte (section)

==Development==
[[File:Mitosis (263 06) Grasshopper testes (Spermatogonia).jpg|thumb|[[Spermatogonia]] going through [[mitosis]] to form primary spermatocytes in Grasshopper [[testes]].|alt=|left]][[File:Spermatocytogenesis.png|thumb|200px|[[Spermatocytogenesis]]|alt=]]At [[puberty]], [[spermatogonia]] located along the walls of the [[seminiferous tubules]] within the [[testis]] will be initiated and start to divide [[mitotically]], forming two types of A cells that contain an oval shaped nucleus with a nucleolus attached to the nuclear envelope; one is dark (Ad) and the other is pale (Ap). The Ad cells are spermatogonia that will stay in the basal compartment (outer region of the tubule); these cells are reserve [[Spermatogonial Stem Cells|spermatogonial stem cells]] that do not usually undergo mitosis. Type Ap are actively-dividing [[Spermatogonial Stem Cells|spermatogonial stem cells]] which begin differentiation to type B spermatogonia, which have round nuclei and heterochromatin attached to the nuclear envelope and the center of nucleolus.<ref>{{Cite journal|last1=Boitani|first1=Carla|last2=Di Persio|first2=Sara|last3=Esposito|first3=Valentina|last4=Vicini|first4=Elena|date=2016-03-05|title=Spermatogonial cells: mouse, monkey and man comparison|journal=Seminars in Cell & Developmental Biology|doi=10.1016/j.semcdb.2016.03.002|issn=1096-3634|pmid=26957475|volume=59|pages=79–88}}</ref> Type B cells will move on to the adluminal compartment (towards the inner region of tubule) and become primary spermatocytes; this process takes about 16 days to complete.<ref name="sperm">{{cite web|last1=Schöni-Affolter|first1=Franzisk|last2=Dubuis-Grieder|first2=Christine|last3=Strauch|first3=Erik Strauch|title=Spermatogenesis|url=http://www.embryology.ch/anglais/cgametogen/spermato03.html#entwicklung|access-date=22 March 2014}}</ref><ref name="Type A and B (JA)">{{cite journal|first=Y|last=Clermont|title=Renewal of spermatogonia in man|year=1966|volume=118|issue=2|journal=American Journal of Anatomy|pages=509–524|doi=10.1002/aja.1001180211|pmid=5917196}}</ref>

The primary spermatocytes within the adluminal compartment will continue on to [[meiosis I]] and divide into two daughters cells, known as secondary spermatocytes, a process which takes 24 days to complete. Each secondary spermatocyte will form two [[spermatids]] after [[meiosis II]].<ref name="Med phy" /><!--p1137-->

Although spermatocytes that divide mitotically and meiotically are sensitive to [[radiation]] and [[cancer]], [[spermatogonial stem cells]] are not. Therefore, after termination of [[radiation therapy]] or [[chemotherapy]], the spermatognia stems cells may re-initiate the formation of spermatogenesis.<ref name="type a and b">{{cite book|url=https://www.inkling.com/read/histology-cell-biology-kierszenbaum-tres-3rd/chapter-20/the-testes|title=Histology and cell biology : an introduction to pathology|last=Tres|first=Abraham L.|last2=Kierszenbaum|first2=Laura L.|publisher=Saunders|year=2012|isbn=9780323078429|edition=3rd|location=Philadelphia, PA|pages=Chapter 20}}</ref>

[[File:1810 Major Pituitary Hormones.jpg|thumb|Hormones produced by the Pituitary gland. GnRH is secreted by the hypothalamus, which induces anterior pituitary to produce FSH and LH upon puberty.]]

===Role of hormones===
The formation of primary spermatocytes (a process known as [[spermatocytogenesis]]) begins in humans when a male is sexually matured at [[puberty]], around the age of 10 through 14.<ref name=gbook>{{cite book|last=Starr|first=Cecie|last2=Taggart|first2=Ralph|last3=Evers|first3=Christine|last4=Starr|first4=Lisa|title=Animal Structure & Function|date=January 1, 2012|publisher=Cengage Learning|isbn=9781133714071|pages=736}}</ref> Formation is initiated upon the pulsated surges of [[gonadotropin-releasing hormone]] (GnRH) from the [[hypothalamus]], which leads to the secretion of [[follicle-stimulating hormone]] (FSH) and [[luteinizing hormone]] (LH) produced by the [[anterior pituitary gland]]. The release of FSH into the testes will enhance spermatogenesis and lead to the development of [[Sertoli cells]], which act as nursing cells where [[spermatids]] will go to mature after [[meiosis II]]. LH promotes [[Leydig cell]] secretion of [[testosterone]] into the testes and blood, which induce spermatogenesis and aid the formation of secondary sex characteristics. From this point on, the secretion of FSH and LH (inducing production of testosterone) will stimulate [[spermatogenesis]] until the male dies.<ref name="human Phys book">{{cite book|last=Sherwood|first=Lauralee|title=Human physiology : from cells to systems|year=2010|publisher=Brooks/Cole, Cengage Learning|location=Australia|isbn=978-0495391845|page=751|edition=7th}}</ref> Increasing the [[hormones]] FSH and LH in males will not increase the rate of spermatogenesis. However, with age, the rate of production will decrease, even when the amount of hormone that is secreted is constant; this is due to higher rates of degeneration of [[germ cells]] during [[meiotic]] [[prophase]].<ref name="Med phy" /><!--p1133-1134-->

===Cell type summary===
In the following table, ploidy, copy number and chromosome/chromatid counts listed are for a single cell, generally prior to DNA synthesis and division (in G<sub>1</sub> if applicable). Primary spermatocytes are arrested after DNA synthesis and prior to division.<ref name="Med phy" /><!--p1137-1138--><ref name=sperm /> 
{| class="wikitable"
|-
!Cell !! Type !! Ploidy/[[Chromosomes]] in human  !!  DNA copy number/[[Chromatids]] in human  !!  Process entered by cell  !!  Duration
 |- 
 |[[spermatogonium]] (types Ad, Ap and B) ||[[germ cells]]|| diploid (2N) / 46 || 2C / 46 || [[spermatocytogenesis]] ([[mitosis]]) || 16 days
 |- 
 | primary spermatocyte ||male [[gametocyte]]|| diploid (2N) / 46 || 4C / 2x46 || [[spermatocytogenesis]] ([[meiosis I]]) || 24 days
 |- 
 | secondary spermatocyte ||male gametocyte|| haploid (N) / 23 || 2C / 46 || [[spermatidogenesis]] ([[meiosis II]]) || A few hours
 |- 
 | [[spermatid]]s ||male [[gametid]]|| haploid (N) / 23  || 1C / 23 || [[spermiogenesis]] ||24 days
 |- 
 |[[spermatozoid]]s ||[[sperm]]|| haploid (N) / 23 || 1C / 23 || spermiation || 64 days (total)
|}