|Embryology - 22 May 2015 Translate|
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- 1 Introduction
- 2 Some Recent Findings
- 3 Spermatozoa Movies
- 4 Seminiferous Tubule
- 5 Spermatozoa Structure
- 6 Human Spermatozoa Development
- 7 Spermatazoa Components
- 8 Meiosis
- 9 Mature Human Spermatozoa
- 10 Spermatozoa Morphology
- 11 Spermatozoa Chemotaxis
- 12 Human Spermatazoa Statistics
- 13 Histology
- 14 Male Abnormalities
- 15 Additional Images
- 16 References
- 17 Terms
- 18 External Links
- 19 Glossary Links
This page introduces spermatogenesis the development of spermatozoa, the male haploid gamete cell. In humans at puberty, spermatozoa are produced by spermatogonia meiosis in the seminiferous tubules of the testis (male gonad). A second process of spermiogenesis leads to change in cellular organisation and shape before release into the central lumen of the seminiferous tubule. This overall process has been variously divided into specific identifiable stages in different species: 6 in human, 12 in mouse, and 14 in rat. Structurally, the seminiferous tubule epithelium is divided into a basal and an apical (adluminal) compartment by the blood–testis barrier (BTB). (More? Testis Development).
A second unique feature of this process is that during mitosis and meiosis the dividing cells remain connected by cytoplasmic bridges as the cells do not complete cytokinesis. This cellular organization is described as a syncytium, only ending with release into the central lumen of the seminiferous tubule, when the cell cytoplasm is discarded.
- In a healthy adult human male it takes about 48 days from meiosis to produce a mature spermatozoa, and he produces somewhere between 45 to 207 million spermatozoa per day, or about 2,000 every second. (More? Statistics)
- Genital Links: Introduction | Lecture - Medicine | Lecture - Science | Online Practical | Primordial Germ Cell | Meiosis | Female | Ovary | Oocyte | Uterus | Vagina | Reproductive Cycles | Menstrual Cycle | Male | Testis | Spermatozoa | Prostate | Genital Movies | Abnormalities | Assisted Reproductive Technology | Puberty | Category:Genital
|Historic Embryology - Genital|
|1902 The Uro-Genital System | 1912 Urinogenital Organ Development | 1921 Urogenital Development | 1921 External Genital Development | Historic Disclaimer|
Some Recent Findings
|More recent papers|
References listed on the rest of the content page and the associated discussion page (listed under the publication year sub-headings) do include some editorial selection based upon both relevance and availability.
Aimee L Katen, Shaun D Roman The genetic consequences of paternal acrylamide exposure and potential for amelioration. Mutat. Res.: 2015, 777;91-100 PMID: 25989052 Kathy Sharp, Donna Bucci, Paul K Zelensky, Alanna Chesney, Wendy Tidhar, David R Broussard, Paul D Heideman Genetic variation in male sexual behaviour in a population of white-footed mice in relation to photoperiod. Anim Behav: 2015, 104;203-212 PMID: 25983335 Qingling Yang, Nan Zhang, Feifei Zhao, Wanli Zhao, Shanjun Dai, Jinhao Liu, Ihtisham Bukhari, Hang Xin, Wenbing Niu, Yingpu Sun Processing of semen by density gradient centrifugation selects spermatozoa with longer telomeres for assisted reproduction techniques. Reprod. Biomed. Online: 2015; PMID: 25982091 Yanan Hai, Min Sun, Minghui Niu, Qingqing Yuan, Ying Guo, Zheng Li, Zuping He BMP4 promotes human Sertoli cell proliferation via Smad1/5 and ID2/3 pathway and its abnormality is associated with azoospermia. Discov Med: 2015, 19(105);311-25 PMID: 25977194 Sandeep Kumar Bansal, Nishi Gupta, Satya Narayan Sankhwar, Singh Rajender Differential Genes Expression between Fertile and Infertile Spermatozoa Revealed by Transcriptome Analysis. PLoS ONE: 2015, 10(5);e0127007 PMID: 25973848
See also Week 1 movies.
Seminiferous tubule cartoon
- Spermatogonia - are the first cells of spermatogenesis
- Primary spermatocyte - large, enter the prophase of the first meiotic division
- Secondary spermatocytes - small, complete the second meiotic division
- Spermatid] - immature spermatozoa
- Spermatozoa - differentiated gamete
- Spermatozoa development: primordial germ cell - spermatogonia - primary spermatocyte - secondary spermatocytes - spermatid - spermatozoa
Spermatozoa (mouse) cross-sections of tail (EM) and diagram
Other main cell types seen in the histological sections
- Sertoli cells- support cells seen within the seminiferous tubule
- Interstitial cells or Leydig cells - produce hormone
- Smooth muscle - surround seminiferous tubule and contribute to contraction of the tubule
Human Spermatozoa Development
- Spermatogenesis process of spermatagonia mature into spermatazoa (sperm).
- Continuously throughout life occurs in the seminiferous tubules in the male gonad- testis (plural testes).
- At puberty spermatagonia activate and proliferate (mitosis).
- about 48 days from entering meiosis until morphologically mature spermatozoa
- about 64 days to complete spermatogenesis, depending reproduction time of spermatogonia
- follicle stimulating hormone (FSH) - stimulates the spermatogenic epithelium
- luteinizing-hormone (LH) - stimulates testosterone production by Leydig cells
- spermatogonial stem cells (SSCs) diploid progenitor for spermatozoa.
- 1963 Clermont identified spermatogonia as Ap (pale) and Ad (dark) on basis of light microscope staining.
- now also type B
- 60 years - Ap spermatogonia number decrease
- 80 years - Ad spermatogonia number decrease
Named after Enrico Sertoli (1842 - 1910) an Italian (Milan) physiologist and histologist.
- sustentacular cells of seminiferous tubules.
- form a “blood-testis” barrier through junctional complexes
- separate the intra-tubular germinal epithelium into two compartments
- basal compartment - cells are exposed to the extra-tubular environment
- luminal compartment - cells are subject to an environment produced by Sertoli cells and germ cells
Spermatozoa (mouse) cross-sections of tail (EM) and diagram
This structure forms the acrosome plate with intermediate filament bundles of the marginal ring at the leading edge of the acrosome. The acroplaxome site for Golgi-derived proacrosomal vesicles to tether and fuse and anchors the developing acrosome to the elongating spermatid head and may provide a scaffolding for the shaping of the spermatid nucleus.
Derived from the Golgi apparatus in conjunction with transient specialized bundles of microtubules (manchette).
The spermatozoa nucleus undergoes extensive compression, and nuclear DNA chromatin remodelling by tightly packing with spermatozoa-specific protamines. 
|It is thought that the lysine-rich protein precursor (H1 histone) has evolved into the arginine-rich protamines.|| Three major spermatozoa nuclear basic proteins types:
|EM Human Spermatozoa Nucleus|
|Cap-phase spermatid nucleus||Elongated spermatid nucleus|
|Normal human spermatozoa||Abnormal human spermatozoa|
The stable mature microtubule-containing tail of the sperm.
|Historic EM spermatozoon tail||Mouse cross-sections of tail|
Sperm contains a centriole which in most mammalian species is contributed to reconstitute the zygotic centrosome. In rodents, only a maternal centrosomal inheritance occurs.
A transient microtubule structure formed in spermatids involved in the process of: assembly of the mammalian sperm tail, mechanical shaping and condensation of the sperm nucleus. These microtubules are also invloved with specific transport, intramanchette transport, which has been likened to intraflagellar transport. This microtubular structure surrounds the nucleus of the developing spermatid and is thought also to assist in both the reshaping of the nucleus and redistribution of spermatid cytoplasm.
Contained in the initial segment provide the energy for motility and may also enter the egg on fertilization, but are eliminated by a ubiquitin-dependent mechanism.
Located in the sperm head perinuclear region and contains a cytoskeletal element to maintain the shape of the sperm head and functional molecules leading to oocyte activation during fertilization.
Spermatozoa maturation involves two processes meiosis and spermiogenesis. After puberty, new spermatozoa continue to be generated throughout life from a spermatogonia stem cell population in the testis.
Differences in Mammalian Meioses
|Female Oogenesis||Male Spermatogenesis|
|Meiosis initiated||once in a finite population of cells||continuously in mitotically dividing stem cell population|
|Gametes produced||1 / meiosis||4 / meiosis|
|Meiosis completed||delayed for months or years||completed in days or weeks|
|Meiosis Arrest||arrest at 1st meiotic prophase||no arrest differentiation proceed continuously|
|Chromosome Equivalence||All chromosomes exhibit equivalent transcription and recombination during meiotic prophase||Sex chromosomes excluded from recombination and transcription during first meiotic prophase|
|Gamete Differentiation||occurs while diploid (in first meiotic prophase)||occurs while haploid (after meiosis ends)|
- Links: Cell Division - Meiosis
Mature Human Spermatozoa
Morphology is a term used to describe the overall appearance of a cell or tissue and is often used to characterise changes in cellular state or activity. Historically, there have been studies comparing the overall appearance of spermatozoa between different species. More recently, there have been several different ways of characterising the morphology of human spermatozoa developed mainly in relation to clinical reproductive technologies.
Integrated Sperm Analysis System (ISAS)
A semi-automated computer-aided system that measures spermatozoa head parameters length (L), width (W), area (A), perimeter (P), acrosomal area (Ac), and the derived values L/W and P/A. 20852650
- For each man a homogeneous population of distributions characterized seminal spermatozoa (7,942 cells: median values L 4.4 μm, W 2.8 μm, A 9.8 μm(2), P 12.5 μm, Ac 47.5%, L/W 1.57, P/A 1.27)
- Different men could have spermatozoa of significantly different dimensions.
- Head dimensions for swim-up spermatozoa from different men (4 812 cells) were similar to those in semen, differing only by 2%-5%.
- The values of L, W and L/W fell within the limits given by the World Health Organization (WHO).
- A subpopulation of 404 spermatozoa considered to fit the stringent criteria of WHO 'normal' seminal spermatozoa from both semen and swim-up were characterized by median values (and 95% confidence intervals) of L, 4.3 μm (3.8-4.9), W, 2.9 μm (2.6-3.3), A, 10.2 μm(2) (8.5-12.2), P, 12.4 μm (11.3-13.9), Ac, 49% (36-60), L/W, 1.49 (1.32-1.67) and P/A, 1.22 (1.11-1.35). These median values fall within the 95th centile confidence limits given by WHO, but the confidence intervals for L and W were larger.
Chemotaxis was first identified in marine species, which still remains today as a model system. While the signals may differ, the overall effect is to chemically attack spermatozoa to the oocyte to allow fertilisation to occur.
| The following series of 2011 research articles have identified the spermatozoa calcium channel protein (CatSper) as the progesterone activated pathway involved in capacitated spermatozoa chemotaxis.
Human Spermatozoa Chemotaxis Model (2009)
See also 2008 review.
Human Spermatazoa Statistics
The following data is based normal human male values for reproductive ages between 20 to 50 years:
- 45 to 207 million spermatozoa produced per day within the two testes
- 2,000 spermatozoa approx per second each day
- Compare this to adult human red blood cell production of about 250,000 million RBCs per day
- 182 million spermatozoa stored (epididymal reserves) up to per epididymis
- 440 million spermatozoa extragonadal stored
- 225 million extragonadal spermatozoa in the ductuli deferentia and caudae epididymides per ejaculation
- 23 million spermatozoa approx (all animals) per gram testicular parenchyma per day
- Transit times
- 0.72 day spermatozoa through the caput
- 0.71 days spermatozoa through the corpus
- 1.76 days spermatozoa through the cauda epididymidis
Papanicolaou stain (Papanicolaou's stain, Pap stain) a multichromatic (five dyes) staining histological technique developed by George Papanikolaou, used to differentiate cells in smear preparations of various bodily secretions.
A clinical score (1-10) for assessing spermatogenesis in a human testicular biopsy. Named after the author of the original article .
|10||complete spermatogenesis and perfect tubules|
|9||many spermatozoa present but disorganized spermatogenesis|
|8||only a few spermatozoa present|
|7||no spermatozoa but many spermatids present|
|6||only a few spermatids present|
|5||no spermatozoa or spermatids present but many spermatocytes present|
|4||only a few spermatocytes present|
|3||only spermatogonia present|
|2||no germ cells present|
|1||neither germ cells nor Sertoli cells present|
|Severe oligozoospermia||less than 1|
|Normal||greater than 20|
(Low Sperm Count) less than 20 million sperm after 72 hour abstinence from sex
(Absent Sperm) blockage of duct network
Immotile Cilia Syndrome
Lack of sperm motility
Human spermatozoa acrosomal protein SP-10 PMID 17012309
Human spermatid electron micrograph PMID 17012309
Model capacitation-induced acrosome docking to sperm membrane PMID 19758979
Mouse spermiogenesis model PMID 19758979
Mouse- seminiferous tubule histology PMID 19758979
Rat Spermatogenesis cartoon PMID 22319669
Human spermatozoa - phospholipase C zeta localization PMID 22428063
Chemotaxis Model PMID 19997608
Labeled Chemotaxis Model PMID 19997608
Spermatogenesis androgen action PMID 20403868
Mouse spermatogenesis stages PMID 20403877
- João Batista A Oliveira, Claudia G Petersen, Fabiana C Massaro, Ricardo L R Baruffi, Ana L Mauri, Liliane F I Silva, Juliana Ricci, José G Franco Motile sperm organelle morphology examination (MSOME): intervariation study of normal sperm and sperm with large nuclear vacuoles. Reprod. Biol. Endocrinol.: 2010, 8;56 PMID: 20529256 | PMC2889997 | Reprod Biol Endocrinol.
- L Maree, S S du Plessis, R Menkveld, G van der Horst Morphometric dimensions of the human sperm head depend on the staining method used. Hum. Reprod.: 2010, 25(6);1369-82 PMID: 20400771
- Han-Chen Ho Redistribution of nuclear pores during formation of the redundant nuclear envelope in mouse spermatids. J. Anat.: 2010, 216(4);525-32 PMID: 20136667
- Yadira Bastián, Ana L Roa-Espitia, Adela Mújica, Enrique O Hernández-González Calpain modulates capacitation and acrosome reaction through cleavage of the spectrin cytoskeleton. Reproduction: 2010, 140(5);673-84 PMID: 20716611
- Manuela Pellegrini, Sara Di Siena, Giuseppina Claps, Silvia Di Cesare, Susanna Dolci, Pellegrino Rossi, Raffaele Geremia, Paola Grimaldi Microgravity promotes differentiation and meiotic entry of postnatal mouse male germ cells. PLoS ONE: 2010, 5(2);e9064 PMID: 20140225
- Yan-Ho Cheng, Elissa Wp Wong, C Yan Cheng Cancer/testis (CT) antigens, carcinogenesis and spermatogenesis. Spermatogenesis: 2011, 1(3);209-220 PMID: 22319669 | PMC3271663 | Spermatogenesis.
- Damien Hunter, Ravinder Anand-Ivell, Sandra Danner, Richard Ivell Models of in vitro spermatogenesis. Spermatogenesis: 2012, 2(1);32-43 PMID: 22553488 | PMC3341244 | Spermatogenesis
- Claire L Borg, Katja M Wolski, Gerard M Gibbs, Moira K O'Bryan Phenotyping male infertility in the mouse: how to get the most out of a 'non-performer'. Hum. Reprod. Update: 2009, 16(2);205-24 PMID: 19758979 | PMC2816191 | Hum Reprod Update.
- Y Clermont Spermatogenesis in man. A study of the spermatogonial population. Fertil. Steril.: 1966, 17(6);705-21 PMID: 5920556
- Abraham L Kierszenbaum, Laura L Tres The acrosome-acroplaxome-manchette complex and the shaping of the spermatid head. Arch. Histol. Cytol.: 2004, 67(4);271-84 PMID: 15700535
- Christina Rathke, Willy M Baarends, Stephan Awe, Renate Renkawitz-Pohl Chromatin dynamics during spermiogenesis. Biochim. Biophys. Acta: 2014, 1839(3);155-68 PMID: 24091090
- Núria Saperas, Juan Ausió Sperm nuclear basic proteins of tunicates and the origin of protamines. Biol. Bull.: 2013, 224(3);127-36 PMID: 23995738
- V A Westbrook, P D Schoppee, G R Vanage, K L Klotz, A B Diekman, C J Flickinger, M A Coppola, J C Herr Hominoid-specific SPANXA/D genes demonstrate differential expression in individuals and protein localization to a distinct nuclear envelope domain during spermatid morphogenesis. Mol. Hum. Reprod.: 2006, 12(11);703-16 PMID: 17012309 | Mol Hum Reprod.
- Farhad Golshan Iranpour The effects of protamine deficiency on ultrastructure of human sperm nucleus. Adv Biomed Res: 2014, 3;24 PMID: 24592371 | Adv Biomed Res.
- D W Fawcett A comparative view of sperm ultrastructure. Biol. Reprod.: 1970, 2;Suppl 2:90-127 PMID: 5521054 | Biol Reprod. PDF
- F R Lillie THE PRODUCTION OF SPERM ISO-AGGLUTININS BY OVA. Science: 1912, 36(929);527-30 PMID: 17735765
- Timo Strünker, Normann Goodwin, Christoph Brenker, Nachiket D Kashikar, Ingo Weyand, Reinhard Seifert, U Benjamin Kaupp The CatSper channel mediates progesterone-induced Ca2+ influx in human sperm. Nature: 2011, 471(7338);382-6 PMID: 21412338
- J V Johannessen [Physicians and leadership]. [Leger og ledelse.] Tidsskr. Nor. Laegeforen.: 1992, 112(23);2950 PMID: 1412339
- Leah Armon, Michael Eisenbach Behavioral mechanism during human sperm chemotaxis: involvement of hyperactivation. PLoS ONE: 2011, 6(12);e28359 PMID: 22163296
- Maria E Teves, Hector A Guidobaldi, Diego R Uñates, Raul Sanchez, Werner Miska, Stephen J Publicover, Aduén A Morales Garcia, Laura C Giojalas Molecular mechanism for human sperm chemotaxis mediated by progesterone. PLoS ONE: 2009, 4(12);e8211 PMID: 19997608
- U Benjamin Kaupp, Nachiket D Kashikar, Ingo Weyand Mechanisms of sperm chemotaxis. Annu. Rev. Physiol.: 2008, 70;93-117 PMID: 17988206
- R P Amann, S S Howards Daily spermatozoal production and epididymal spermatozoal reserves of the human male. J. Urol.: 1980, 124(2);211-5 PMID: 6772801
- S G Johnsen Testicular biopsy score count--a method for registration of spermatogenesis in human testes: normal values and results in 335 hypogonadal males. Hormones: 1970, 1(1);2-25 PMID: 5527187
- Spermatogenesis | PubMed - Spermatogenesis "Spermatogenesis is a new quarterly, peer-reviewed journal that will publish high-quality articles covering all aspects of spermatogenesis."
- WHO. WHO Laboratory Manual for the Examination and Processing of Human Semen. 5th ed. Geneva, Switzerland: World Health Organization; 2010. Online PDF
Shosei Yoshida Stem cells in mammalian spermatogenesis. Dev. Growth Differ.: 2010, 52(3);311-7 PMID: 20388168
Cathryn A Hogarth, Michael D Griswold The key role of vitamin A in spermatogenesis. J. Clin. Invest.: 2010, 120(4);956-62 PMID: 20364093
Saleela M Ruwanpura, Robert I McLachlan, Sarah J Meachem Hormonal regulation of male germ cell development. J. Endocrinol.: 2010, 205(2);117-31 PMID: 20144980
Louis Hermo, R-Marc Pelletier, Daniel G Cyr, Charles E Smith Surfing the wave, cycle, life history, and genes/proteins expressed by testicular germ cells. Part 1: background to spermatogenesis, spermatogonia, and spermatocytes. Microsc. Res. Tech.: 2010, 73(4);241-78 PMID: 19941293
Louis Hermo, R-Marc Pelletier, Daniel G Cyr, Charles E Smith Surfing the wave, cycle, life history, and genes/proteins expressed by testicular germ cells. Part 2: changes in spermatid organelles associated with development of spermatozoa. Microsc. Res. Tech.: 2010, 73(4);279-319 PMID: 19941292
U Benjamin Kaupp, Nachiket D Kashikar, Ingo Weyand Mechanisms of sperm chemotaxis. Annu. Rev. Physiol.: 2008, 70;93-117 PMID: 17988206
Edward M Eddy, Kiyotaka Toshimori, Deborah A O'Brien Fibrous sheath of mammalian spermatozoa. Microsc. Res. Tech.: 2003, 61(1);103-15 PMID: 12672126
- StemBook [Internet]. Cambridge (MA): Harvard Stem Cell Institute; 2008 Regulation of spermatogonia
- asthenozoospermia - (asthenospermia) Term for reduced sperm motility and can be the cause of male infertility.
- blood-testis barrier - (BTB) Formed by tight junctions, basal ectoplasmic specializations, desmosome-like junctions and gap junctions between adjacent Sertoli cells near the basement membrane of the seminiferous epithelium.
- capacitation - term describing the process by which spermaozoa become capable of fertilizing an oocyte, requires membrane changes, removal of surface glycoproteins and increased motility.
- Leydig cell - (interstitial cell) Male gonad (testis) cell which secrete the androgen testosterone, beginning in the fetus. These cells are named after Franz von Leydig (1821 - 1908) a German scientist who histologically described these cells.
- primary spermatocyte - arranged in the seminiferous tubule wall deep (luminal) to the spermatogonia. These large cells enter the prophase of the first meiotic division. (More? Meiosis)
- Sertoli cells - (sustentacular cell) These cells are the spermatozoa supporting cells, nutritional and mechanical, as well as forming a blood-testis barrier. The cell cytoplasm spans all layers of the seminiferous tubule. The cells are named after Enrico Sertoli (1842 - 1910), and italian physiologist and histologist.
- sperm annulus - (Jensen's ring; Latin, annulus = ring) A region of the mammalian sperm flagellum connecting the midpiece and the principal piece. The annulus is a septin-based structure formed from SEPT1, 4, 6, 7 and 12. Septins are polymerizing GTPases that can act as a scaffold forming hetero-oligomeric filaments required for cytokinesis and other cell cycle roles.
- spermatogenesis - (Greek, genesis = origin, creation, generation) The term used to describe the process of diploid spermatagonia division and differentiation to form haploid spermatazoa within the testis (male gonad). The process includes the following cellular changes: meiosis, reoorganization of DNA, reduction in DNA content, reorganization of cellular organelles, morphological changes (cell shape). The final process of change in cell shape is also called spermiogenesis.
- spermatogenesis - (Greek, genesis = origin, creation, generation) The maturation process of the already haploid spermatazoa into the mature sperm shape and organization. This process involves reorganization of cellular organelles (endoplasmic reticulum, golgi apparatus, mitochondria), cytoskeletal changes (microtubule organization) and morphological changes (cell shape, acrosome and tail formation).
- spermatogonia - The cells located in the seminiferous tubule adjacent to the basal membrane that either divide and separate to renew the stem cell population, or they divide and stay together as a pair (Apr spermatogonia) connected by an intercellular cytoplasmic bridge to differentiate and eventually form spermatazoa.
- spermatozoa head - Following spermiogenesis, the first region of the spermatozoa containing the haploid nucleus and acrosome. In humans, it is a flattened structure (5 µm long by 3 µm wide) with the posterior part of nuclear membrane forming the basal plate region. The human spermatozoa is about 60 µm long, actively motile and divided into 3 main regions (head, neck and spermatozoa tail).
- spermatozoa neck - Following spermiogenesis, the second region of the spermatozoa attached to basal plate, transverse oriented centriole, contains nine segmented columns of fibrous material, continue as outer dense fibres in tail. In humans, it forms a short structure (1 µm). The human spermatozoa is about 60 µm long, actively motile and divided into 3 main regions (head, neck and tail).
- spermatozoa tail - Following spermiogenesis, the third region of the spermatozoa that has a head, neck and tail). The tail is also divided into 3 structural regions a middle piece, a principal piece and an end piece. In humans: the middle piece (5 µm long) is formed by axonema and dense fibres surrounded by mitochondria; the principal piece (45 µm long) fibrous sheath interconnected by regularly spaced circumferential hoops; the final end piece (5 µm long) has an axonema surrounded by small amount of cytoplasm and plasma membrane.
- spermatogonial stem cells - (SSCs) The spermatagonia cells located beside the seminiferous tubule basal membrane that either divide and separate to renew the stem cell population, or they divide and stay together as a pair (|Apr spermatogonia) connected by an intercellular cytoplasmic bridge to differentiate and eventually form spermatazoa.
- sperm protein 56 - A component of the spermatozoa acrosomal matrix released to the sperm surface during capacitation.
External Links Notice - The dynamic nature of the internet may mean that some of these listed links may no longer function. If the link no longer works search the web with the link text or name.
- World Health Organization - WHO Laboratory Manual for the Examination and Processing of Human Semen. 5th ed. Geneva, Switzerland: World Health Organization; 2010. Online PDF
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Cite this page: Hill, M.A. (2015) Embryology Spermatozoa Development. Retrieved May 22, 2015, from https://embryology.med.unsw.edu.au/embryology/index.php/Spermatozoa_Development
- © Dr Mark Hill 2015, UNSW Embryology ISBN: 978 0 7334 2609 4 - UNSW CRICOS Provider Code No. 00098G