This page covers the topic of spermatogenesis, the production of the male gametes. It all starts with a "kiss", KiSS-1 (kisspeptin-121) cleaved to metastin appears to have an important role in the onset of puberty where there is also a proliferation of Sertoli cells (More? Puberty | Kisspeptin). Human males of reproductive age (20 to 50 years old) produce between 45 to 207 million spermatozoa per day within the two testes. This figure is similar to the spermatazoa numbers by parenchyma mass produced in other species. (More? Spermatazoa Statistics)
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Histology sections through the testis seminiferous tubule (Images: UWA Blue Histology) |
There are 2 main steps in gamete formation: Meiosis and halving chromosome number (diploid to haploid) and Spermiogenesis which is the morphological (or shape) maturation of the spermatazoa.
In meiosis, each diploid stem cell (spermatogonia) 4 haploid gametes (spermatazoa) are produced; 2 sperm each contain an X chromosome and have the potential to produce female offspring, 2 sperm each contain a Y chromosome and and have the potential to produce male offspring.
In spermiogenesis, each immature spermatocyte develops an acrosome, and tail, reorganizes mitochondria and looses the majority of its cytoplasm.
Up to 75% of male germ cells generated are lost by apoptosis (programmed cell death) this is thought to be a mechanism to remove defective germ cells.
Page Links: Introduction | Some Recent Findings | Spermatazoa Statistics | Spermatazoa Components | Overview | Spermatogenesis Abnormalities | Artificial Testis | Sperm Gene Expression | Testis Histology | WWW Links | References | Search Medline | Glossary | Spermatogenesis Terms
Related Pages: Capacitation | Y chromosome | Male | Male Accessory Glands | Puberty | Genital Stage 13/14 Embryo | Genital Stage 22 Embryo | Genital Stage 22 Highpower | Movie - Primordial Germ Cell Migration |
Amann RP, Howards SS. Hormonal regulation of spermatogenesis and spermiogenesis. J Steroid Biochem Mol Biol. 2008 Mar 6 Okada H, Tajima A, Shichiri K, Tanaka A, Tanaka K, Inoue I. Genome-wide expression of azoospermia testes demonstrates a specific profile and implicates ART3 in genetic susceptibility. PLoS Genet. 2008 Feb;4(2):e26. Kierszenbaum AL, Rivkin E, Tres LL. Molecular biology of sperm head shaping. Soc Reprod Fertil Suppl. 2007;65:33-43. Review. Qi H, Moran MM, Navarro B, Chong JA, Krapivinsky G, Krapivinsky L, Kirichok Y, Ramsey IS, Quill TA, Clapham DE. From the Cover: All four CatSper ion channel proteins are required for male fertility and sperm cell hyperactivated motility. Proc Natl Acad Sci U S A. 2007 Jan 23;104(4):1219-23. Epub 2007 Jan 16.
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The following data is based normal human male values for reproductive ages between 20 to 50 years:
(Data: Amann RP, Howards SS., 1980 and Gordon-Smith EC., 2007)
Acroplaxome - forms the acrosome plate with intermediate filament bundles of the marginal ring at the leading edge of the acrosome. (More? review acrosome-acroplaxome-manchette complex) Acrosome - derived from the Golgi apparatus in conjunction with transient specialized bundles of microtubules (manchette). Axoneme - the stable mature microtubule-containing tail of the sperm. Centriole - sperm contains a centriole which in most mammalian species is contributed to reconstitute the zygotic centrosome. In rodents, only a maternal centrosomal inheritance occurs. Manchette - 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 aslo ivloved with specific transport, intramanchette transport, which has been likened to intraflagellar transport. Mitochondria - 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. Perinuclear Theca - 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. |
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Testis (cat) cross-section showing seminferous tubule and epididymis.
Virtual Slidebox of Histology Male genital tract
Blue Histology Male Reproductive System
Sample histological images of the testis are based upon UNSW Slides 86, 87, 87A. Below each image is a brief list of features in each image. There are also Histological images (and a test quiz) available from other external WWW sites.
The Department of Anatomy UNSW also has an excellent Histology Program under development "The Fabric of Life"(for more details contact Dr B. Freeman). This
program is currently only available from computers within the Department of Anatomy or the Biomedical Library.
Oligospermia (Low Sperm Count)
Defined as less than 20 million sperm present after 72 hour abstinence from sex.
Azoospermia (Absent Sperm) Two main forms identified as:
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Okada H, Tajima A, Shichiri K, Tanaka A, Tanaka K, Inoue I. Genome-wide expression of azoospermia testes demonstrates a specific profile and implicates ART3 in genetic susceptibility. PLoS Genet. 2008 Feb;4(2):e26. |
Human Seminiferious Tubule - Non-obstructive azoospermia and Obstructive azoospermia (Image: Okada, etal, 2008) |
Immotile Cilia Syndrome
lack of sperm motility
Globozoospermia (round-headed spermatozoa)
Acrosome malformation of spermatids (More? Acrosome Malformation)
Ostermeier GC, Dix DJ, Miller D, Khatri P, Krawetz SA. Spermatozoal RNA profiles of normal fertile men. Lancet. 2002 Sep 7;360(9335):772-7.
".... Moreover, the data suggest that, in addition to delivering the paternal genome, spermatozoa provide the zygote with a unique suite of paternal mRNAs."
Ostermeier GC, Goodrich RJ, Moldenhauer JS, Diamond MP, Krawetz SA. A suite of novel human spermatozoal RNAs. J Androl. 2005 Jan-Feb;26(1):70-4.
Piwi-interfering RNAs (piRNAs) - small RNA (19-30 nt) mammalian testis which interacts with the Argonaught PIWI subfamily. Suggested to have a role in spermatogenesis.
Argonaut family:
Sofikitis N, Pappas E, Kawatani A, Baltogiannis D, Loutradis D, Kanakas N, Giannakis D, Dimitriadis F, Tsoukanelis K, Georgiou I, Makrydimas G, Mio Y, Tarlatzis V, Melekos M, Miyagawa I. Efforts to create an artificial testis: culture systems of male germ cells under biochemical conditions resembling the seminiferous tubular biochemical environment. Hum Reprod Update. 2005 May-Jun;11(3):229-59. Epub 2005 Apr 7. Review.
"This review focuses on the methodologies that have been proved sufficient to achieve differentiation of cultured male germ cells. Furthermore, the factors regulating spermatogenesis and the technical prerequisites to achieve differentiation of cultured male germ cells are described."
Back to Urogenital Notes 1 | 2 | 3 | 4 | Page 5 (histo)
Reviews
Yan HH, Mruk DD, Lee WM, Cheng CY. Ectoplasmic specialization: a friend or a foe of spermatogenesis? Bioessays. 2007 Jan;29(1):36-48.
Park SY, Jameson JL. Minireview: transcriptional regulation of gonadal development and differentiation. Endocrinology. 2005 Mar;146(3):1035-42.
Tanaka H, Baba T. Gene expression in spermiogenesis. Cell Mol Life Sci. 2005 Feb;62(3):344-54.
Mieusset R, Soulie M. Hypospadias: psychosocial, sexual, and reproductive consequences in adult life. J Androl. 2005 Mar-Apr;26(2):163-8.
Sofikitis N, Pappas E, Kawatani A, Baltogiannis D, Loutradis D, Kanakas N, Giannakis D, Dimitriadis F, Tsoukanelis K, Georgiou I, Makrydimas G, Mio Y, Tarlatzis V, Melekos M, Miyagawa I. Efforts to create an artificial testis: culture systems of male germ cells under biochemical conditions resembling the seminiferous tubular biochemical environment. Hum Reprod Update. 2005 May-Jun;11(3):229-59. Epub 2005 Apr 7.
Kierszenbaum AL, Tres LL. The acrosome-acroplaxome-manchette complex and the shaping of the spermatid head. Arch Histol Cytol. 2004 Nov;67(4):271-84. Review.
Articles
Okada H, Tajima A, Shichiri K, Tanaka A, Tanaka K, Inoue I. Genome-wide expression of azoospermia testes demonstrates a specific profile and implicates ART3 in genetic susceptibility. PLoS Genet. 2008 Feb;4(2):e26.
Amann RP, Howards SS. Hormonal regulation of spermatogenesis and spermiogenesis. J Steroid Biochem Mol Biol. 2008 Mar 6
Gur Y, Breitbart H. [See Related Articles] Mammalian sperm translate nuclear-encoded proteins by mitochondrial-type ribosomes. Genes Dev. 2006 Feb 15;20(4):411-6.
Ostermeier GC, Goodrich RJ, Moldenhauer JS, Diamond MP, Krawetz SA. [See Related Articles] Spermatozoal RNA profiles of normal fertile men. Lancet. 2002 Sep 7;360(9335):772-7.
Ostermeier GC, Goodrich RJ, Moldenhauer JS, Diamond MP, Krawetz SA. A suite of novel human spermatozoal RNAs. J Androl. 2005 Jan-Feb;26(1):70-4.
Amann RP, Howards SS. Daily spermatozoal production and epididymal spermatozoal reserves of the human male. J Urol. 1980 Aug;124(2):211-5.
Sofikitis N, Giotitsas N, Tsounapi P, Baltogiannis D, Giannakis D, Pardalidis N.
Recent 2006
Hedgehog homeobox signaling in Spermatogenesis Deletion of Dhh, a hedgehog homeobox gene, has been previously shown to lead to male infertility. Szczepny A, Hime GR, Loveland KL. Expression of hedgehog signalling components in adult mouse testis. Dev Dyn. 2006 Nov;235(11):3063-70.
"In the first wave of spermatogenesis, mRNAs encoding all three Glis are detected in spermatogonia and Sertoli cells. In adult mouse testes, these transcripts are observed in spermatogonia and spermatocytes, with reduced signal intensity in round spermatids. The mRNAs encoding key effectors of Hh signalling, Ptc2, Smo, and Fu, are also most apparent in spermatogonia, spermatocytes, and to a lower extent in round spermatids. In contrast, mRNA encoding SuFu, a negative regulator of Hh signalling, was most predominant in round spermatids and the protein is evident in round and elongating spermatids, suggesting that SuFu protein may switch off Hh signalling in haploid germ cells."
Progestin and Meiosis Miura T, Higuchi M, Ozaki Y, Ohta T, Miura C. Progestin is an essential factor for the initiation of the meiosis in spermatogenetic cells of the eel. Proc Natl Acad Sci U S A. 2006 May 1 [Epub ahead of print]
"...Progestins are important steroids regulating final maturation in male and female vertebrates. ...A natural progestin in teleost fish 17alpha,20beta-dihydroxy-4-pregnen-3-one (DHP) and its receptors were present in the testis at an early stage of spermatogenesis. ...We conclude that DHP, a progestin, is an essential factor for the initiation of meiosis."
Sperm Ribosomes Gur Y, Breitbart H. Mammalian sperm translate nuclear-encoded proteins by mitochondrial-type ribosomes. Genes Dev. 2006 Feb 15;20(4):411-6.
"It is widely accepted that spermatozoa are translationally silent. The present study demonstrates, for the first time, incorporation of labeled amino acids into polypeptides during sperm capacitation, which was completely inhibited by mitochondrial translation inhibitors but not by the cytoplasmic translation inhibitor. .... Thus, contrary to the accepted dogma, nuclear genes are expressed as proteins in sperm during their residence in the female reproductive tract until fertilization."
Red Blood Cell Counts- Gordon-Smith, EC Red blood cells Surgery 2007 Feb; 25: 57-60.
Search PubMed: Feb 2007 "spermatogenesis" 16,798 reference articles of which 1,819 were reviews.
Search PubMed Now: spermatogenesis | spermatazoa development | spermiogenesis |
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