Talk:Spermatozoa Development

About Discussion Pages

On this website the Discussion Tab or "talk pages" for a topic has been used for several purposes: References - recent and historic that relates to the topic Additional topic information - currently prepared in draft format Links - to related webpages Topic page - an edit history as used on other Wiki sites Lecture/Practical - student feedback Student Projects - online project discussions. Links: Pubmed Most Recent | Reference Tutorial | Journal Searches Glossary Links Glossary: A | B | C | D | E | F | G | H | I | J | K | L | M | N | O | P | Q | R | S | T | U | V | W | X | Y | Z | Numbers | Symbols | Term Link Cite this page: Hill, M.A. (2024, May 5) Embryology Spermatozoa Development. Retrieved from https://embryology.med.unsw.edu.au/embryology/index.php/Talk:Spermatozoa_Development

original page http://embryology.med.unsw.edu.au/Notes/week1_3b.htm

2012

The generation of spermatogonial stem cells and spermatogonia in mammals

Reprod Biol. 2012 Mar;12(1):5-23.

Kolasa A, Misiakiewicz K, Marchlewicz M, Wiszniewska B. Source Department of Histology and Embryology, Pomeranian Medical University in Szczecin, 72 Powstańców Wielkopolskich Str., 70-111 Szczecin, Poland; e-mail: ak1712@pum.edu.pl. Abstract Spermatogenesis is a complex series of cellular changes leading to the formation of haploid male gametes (spermatozoa) and includes mitotic, meiotic and post-meiotic phases. Spermatogonial stem cells (SSCs) are essential for the continuous lifelong production of spermatozoa. Spermatogenesis is initiated when SSC is triggered to undergo mitosis that gives rise to progenitors, which further differentiate into spermatogonia. In this review, we describe the origin of SSCs and other spermatogonia populations and summarize the knowledge concerning their markers.

PMID 22472937

http://repbiol.pan.olsztyn.pl/docs/pdfs/repbiol_vol12_num1_page5.pdf

2011

The role of the septin family in spermiogenesis

Spermatogenesis. 2011 Oct;1(4):298-302. Epub 2011 Oct 1.

Lin YH, Kuo YC, Chiang HS, Kuo PL. Source Graduate Institute of Basic Medicine; Fu Jen Catholic University; Taipei, Taiwan. Abstract SEPTINS (FULL NAME: Septin; symbol name: SEPT) belong to a family of polymerizing GTP-binding proteins that are required for many cellular functions, including membrane compartmentalization, vesicle trafficking, mitosis and cytoskeletal remodeling. Two of the 14 family members in the mammalian species, Septin12 and 14 are expressed specifically in the testis. In the mouse, knockout of Septin4 and Septin12 leads to male sterility with distinctive sperm pathology (defective annulus or bent neck). In humans, sperm with abnormal expression patterns of SEPT4, 7 and 12 are more prevalent in infertile men. How septin filament is assembled/dissembled and how the SEPT-related complex regulates spermatogenesis still await further investigation.

PMID 22332113

Behavioral Mechanism during Human Sperm Chemotaxis: Involvement of Hyperactivation

Armon L, Eisenbach M. Source

Department of Biological Chemistry, The Weizmann Institute of Science, Rehovot, Israel.

Abstract

When mammalian spermatozoa become capacitated they acquire, among other activities, chemotactic responsiveness and the ability to exhibit occasional events of hyperactivated motility-a vigorous motility type with large amplitudes of head displacement. Although a number of roles have been proposed for this type of motility, its function is still obscure. Here we provide evidence suggesting that hyperactivation is part of the chemotactic response. By analyzing tracks of spermatozoa swimming in a spatial chemoattractant gradient we demonstrate that, in such a gradient, the level of hyperactivation events is significantly lower than in proper controls. This suggests that upon sensing an increase in the chemoattractant concentration capacitated cells repress their hyperactivation events and thus maintain their course of swimming toward the chemoattractant. Furthermore, in response to a temporal concentration jump achieved by photorelease of the chemoattractant progesterone from its caged form, the responsive cells exhibited a delayed turn, often accompanied by hyperactivation events or an even more intense response in the form of flagellar arrest. This study suggests that the function of hyperactivation is to cause a rather sharp turn during the chemotactic response of capacitated cells so as to assist them to reorient according to the chemoattractant gradient. On the basis of these results a model for the behavior of spermatozoa responding to a spatial chemoattractant gradient is proposed.

PMID 22163296

http://www.plosone.org/article/info%3Adoi%2F10.1371%2Fjournal.pone.0028359

Doubly uniparental inheritance of mitochondria as a model system for studying germ line formation

PLoS One. 2011;6(11):e28194. Epub 2011 Nov 29.

Milani L, Ghiselli F, Maurizii MG, Passamonti M. Source Department of Biologia Evoluzionistica Sperimentale, University of Bologna, Bologna, Italy.

Abstract

BACKGROUND: Doubly Uniparental Inheritance (DUI) of mitochondria occurs when both mothers and fathers are capable of transmitting mitochondria to their offspring, in contrast to the typical Strictly Maternal Inheritance (SMI). DUI was found in some bivalve molluscs, in which two mitochondrial genomes are inherited, one through eggs, the other through sperm. During male embryo development, spermatozoon mitochondria aggregate in proximity of the first cleavage furrow and end up in the primordial germ cells, while they are dispersed in female embryos. METHODOLOGY/PRINCIPAL FINDINGS: We used MitoTracker, microtubule staining and transmission electron microscopy to examine the mechanisms of this unusual distribution of sperm mitochondria in the DUI species Ruditapes philippinarum. Our results suggest that in male embryos the midbody deriving from the mitotic spindle of the first division concurs in positioning the aggregate of sperm mitochondria. Furthermore, an immunocytochemical analysis showed that the germ line determinant Vasa segregates close to the first cleavage furrow. CONCLUSIONS/SIGNIFICANCE: In DUI male embryos, spermatozoon mitochondria aggregate in a stable area on the animal-vegetal axis: in organisms with spiral segmentation this zone is not involved in cleavage, so the aggregation is maintained. Moreover, sperm mitochondria reach the same embryonic area in which also germ plasm is transferred. In 2-blastomere embryos, the segregation of sperm mitochondria in the same region with Vasa suggests their contribution in male germ line formation. In DUI male embryos, M-type mitochondria must be recognized by egg factors to be actively transferred in the germ line, where they become dominant replacing the Balbiani body mitochondria. The typical features of germ line assembly point to a common biological mechanism shared by DUI and SMI organisms. Although the molecular dynamics of the segregation of sperm mitochondria in DUI species are unknown, they could be a variation of the mechanism regulating the mitochondrial bottleneck in all metazoans.

PMID 22140544

The CatSper channel mediates progesterone-induced Ca2+ influx in human sperm

Nature. 2011 Mar 17;471(7338):382-6.

Strünker T, Goodwin N, Brenker C, Kashikar ND, Weyand I, Seifert R, Kaupp UB. Source Center of Advanced European Studies and Research, Abteilung Molekulare Neurosensorik, Ludwig-Erhard-Allee 2, 53175 Bonn, Germany. timo.struenker@caesar.de

Abstract

In the oviduct, cumulus cells that surround the oocyte release progesterone. In human sperm, progesterone stimulates a Ca(2+) increase by a non-genomic mechanism. The Ca(2+) signal has been proposed to control chemotaxis, hyperactivation and acrosomal exocytosis of sperm. However, the underlying signalling mechanism has remained mysterious. Here we show that progesterone activates the sperm-specific, pH-sensitive CatSper Ca(2+) channel. We found that both progesterone and alkaline pH stimulate a rapid Ca(2+) influx with almost no latency, incompatible with a signalling pathway involving metabotropic receptors and second messengers. The Ca(2+) signals evoked by alkaline pH and progesterone are inhibited by the Ca(v) channel blockers NNC 55-0396 and mibefradil. Patch-clamp recordings from sperm reveal an alkaline-activated current carried by mono- and divalent ions that exhibits all the hallmarks of sperm-specific CatSper Ca(2+) channels. Progesterone substantially enhances the CatSper current. The alkaline- and progesterone-activated CatSper current is inhibited by both drugs. Our results resolve a long-standing controversy over the non-genomic progesterone signalling. In human sperm, either the CatSper channel itself or an associated protein serves as the non-genomic progesterone receptor. The identification of CatSper channel blockers will greatly facilitate the study of Ca(2+) signalling in sperm and help to define further the physiological role of progesterone and CatSper.

PMID 21412338

Progesterone activates the principal Ca2+ channel of human sperm

Nature. 2011 Mar 17;471(7338):387-91.

Lishko PV, Botchkina IL, Kirichok Y. Source Department of Physiology, University of California San Francisco, UCSF Mail Code 2140, Genentech Hall Room N272F, 600 16th Street, San Francisco, California 94158, USA.

Abstract

Steroid hormone progesterone released by cumulus cells surrounding the egg is a potent stimulator of human spermatozoa. It attracts spermatozoa towards the egg and helps them penetrate the egg's protective vestments. Progesterone induces Ca(2+) influx into spermatozoa and triggers multiple Ca(2+)-dependent physiological responses essential for successful fertilization, such as sperm hyperactivation, acrosome reaction and chemotaxis towards the egg. As an ovarian hormone, progesterone acts by regulating gene expression through a well-characterized progesterone nuclear receptor. However, the effect of progesterone upon transcriptionally silent spermatozoa remains unexplained and is believed to be mediated by a specialized, non-genomic membrane progesterone receptor. The identity of this non-genomic progesterone receptor and the mechanism by which it causes Ca(2+) entry remain fundamental unresolved questions in human reproduction. Here we elucidate the mechanism of the non-genomic action of progesterone on human spermatozoa by identifying the Ca(2+) channel activated by progesterone. By applying the patch-clamp technique to mature human spermatozoa, we found that nanomolar concentrations of progesterone dramatically potentiate CatSper, a pH-dependent Ca(2+) channel of the sperm flagellum. We demonstrate that human CatSper is synergistically activated by elevation of intracellular pH and extracellular progesterone. Interestingly, human CatSper can be further potentiated by prostaglandins, but apparently through a binding site other than that of progesterone. Because our experimental conditions did not support second messenger signalling, CatSper or a directly associated protein serves as the elusive non-genomic progesterone receptor of sperm. Given that the CatSper-associated progesterone receptor is sperm specific and structurally different from the genomic progesterone receptor, it represents a promising target for the development of a new class of non-hormonal contraceptives.

PMID 21412339

2010

Dimensions of human ejaculated spermatozoa in Papanicolaou-stained seminal and swim-up smears obtained from the Integrated Semen Analysis System (ISAS(®))

Asian J Androl. 2010 Sep 20. [Epub ahead of print]

Bellastella G, Cooper TG, Battaglia M, Ströse A, Torres I, Hellenkemper B, Soler C, Sinisi AA.

[1] Centre of Reproductive Medicine and Andrology of the University, Münster D-48149, Germany [2] Department of Clinical and Experimental Medicine and Surgery, Endocrinology and Medical Andrology Section, Seconda Universita`di Napoli, Napoli 80131, Italy.

Objective measurements are required for computer-aided sperm morphometric analysis (CASMA) machines to distinguish normal from abnormal sperm heads. The morphometric characteristics of spermatozoa in 72 samples of semen and of spermatozoa from 72 other semen samples after swim-up were quantified by the semi-automated Integrated Sperm Analysis System (ISAS) computer-aided system, which measured the sperm head parameters length (L), width (W), area (A), perimeter (P), acrosomal area (Ac), and the derived values L/W and P/A. 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), and there was no significant difference in within- and among-individual variation. 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). Although these samples were not biologically matched, linear mixed-effects statistical analyses permitted valid comparison of the groups. 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. Although these differences in head dimensions among men and after swim-up could be detected by CASMA, the small differences make it unlikely that technicians would be able to distinguish them. The values could be used as default sperm head values for the CASMA machine used here.

PMID 20852650

Microgravity promotes differentiation and meiotic entry of postnatal mouse male germ cells

Pellegrini M, Di Siena S, Claps G, Di Cesare S, Dolci S, Rossi P, Geremia R, Grimaldi P. PLoS One. 2010 Feb 4;5(2):e9064. PMID: 20140225 | PLoS One

"A critical step of spermatogenesis is the entry of mitotic spermatogonia into meiosis. Progresses on these topics are hampered by the lack of an in vitro culture system allowing mouse spermatogonia differentiation and entry into meiosis. Previous studies have shown that mouse pachytene spermatocytes cultured in simulated microgravity (SM) undergo a spontaneous meiotic progression. Here we report that mouse mitotic spermatogonia cultured under SM with a rotary cell culture system (RCCS) enter into meiosis in the absence of any added exogenous factor or contact with somatic cells."

http://www.ncbi.nlm.nih.gov/pmc/articles/PMC2847216/?tool=pubmed

The biology of spermatogenesis: the past, present and future

Philos Trans R Soc Lond B Biol Sci. 2010 May 27;365(1546):1459-63.

Cheng CY, Mruk DD. Source The Mary M. Wohlford Laboratory for Male Contraceptive Research, Population Council, 1230 York Avenue, New York, NY 10065, USA. y-cheng@popcbr.rockefeller.edu

Abstract

The physiological function of spermatogenesis in Caenorhabditis elegans, Drosophila melanogaster and mammals is to produce spermatozoa (1n, haploid) that contain only half of the genetic material of spermatogonia (2n, diploid). This half number of chromosomes from a spermatozoon will then be reconstituted to become a diploid cell upon fertilization with an egg, which is also haploid. Thus, genetic information from two parental individuals can be passed onto their offspring. Spermatogenesis takes place in the seminiferous epithelium of the seminiferous tubule, the functional unit of the mammalian testis. In mammals, particularly in rodents, the fascinating morphological changes that occur during spermatogenesis involving cellular differentiation and transformation, mitosis, meiosis, germ cell movement, spermiogenesis and spermiation have been well documented from the 1950s through the 1980s. During this time, however, the regulation of, as well as the biochemical and molecular mechanisms underlying these diverse cellular events occurring throughout spermatogenesis, have remained largely unexplored. In the past two decades, important advancements have been made using new biochemical, cell and molecular biology techniques to understand how different genes, proteins and signalling pathways regulate various aspects of spermatogenesis. These include studies on the differentiation of spermatogonia from gonocytes; regulation of spermatogonial stem cells; regulation of spermatogonial mitosis; regulation of meiosis, spermiogenesis and spermiation; role of hormones (e.g. oestrogens, androgens) in spermatogenesis; transcriptional regulation of spermatogenesis; regulation of apoptosis; cell-cell interactions; and the biology of junction dynamics during spermatogenesis. The impact of environmental toxicants on spermatogenesis has also become an urgent issue in the field in light of declining fertility levels in males. Many of these studies have helped investigators to understand important similarities, differences and evolutionary relationships between C. elegans, D. melanogaster and mammals relating to spermatogenesis. In this Special Issue of the Philosophical Transactions of the Royal Society B: Biological Sciences, we have covered many of these areas, and in this Introduction, we highlight the topic of spermatogenesis by examining its past, present and future.

PMID 20403863 [PubMed - indexed for MEDLINE] PMCID: PMC2871927

2009

Capacity for stochastic self-renewal and differentiation in mammalian spermatogonial stem cells

J Cell Biol. 2009 Nov 16;187(4):513-24. Epub 2009 Nov 9.

Wu Z, Luby-Phelps K, Bugde A, Molyneux LA, Denard B, Li WH, Süel GM, Garbers DL. Source Cecil H. and Ida Green Center for Reproductive Biology Sciences, Department of Pharmacology, University of Texas Southwestern Medical Center, Dallas, TX 75390, USA. zhuoru.wu@utsouthwestern.edu Abstract Mammalian spermatogenesis is initiated and sustained by spermatogonial stem cells (SSCs) through self-renewal and differentiation. The basic question of whether SSCs have the potential to specify self-renewal and differentiation in a cell-autonomous manner has yet to be addressed. Here, we show that rat SSCs in ex vivo culture conditions consistently give rise to two distinct types of progeny: new SSCs and differentiating germ cells, even when they have been exposed to virtually identical microenvironments. Quantitative experimental measurements and mathematical modeling indicates that fate decision is stochastic, with constant probability. These results reveal an unexpected ability in a mammalian SSC to specify both self-renewal and differentiation through a self-directed mechanism, and further suggest that this mechanism operates according to stochastic principles. These findings provide an experimental basis for autonomous and stochastic fate choice as an alternative strategy for SSC fate bifurcation, which may also be relevant to other stem cell types.

PMID: 19948499 http://www.ncbi.nlm.nih.gov/pubmed/19948499

PMCID: PMC2779229 http://www.ncbi.nlm.nih.gov/pmc/articles/PMC2779229

http://jcb.rupress.org/content/187/4/513.long

New insights into epididymal biology and function

Hum Reprod Update. 2009 Mar-Apr;15(2):213-27. Epub 2009 Jan 8.

Cornwall GA.

Department of Cell Biology and Biochemistry, Texas Tech University Health Sciences Center, Lubbock, 79430, USA. gail.cornwall@ttuhsc.edu Abstract BACKGROUND: The epididymis performs an important role in the maturation of spermatozoa including their acquisition of progressive motility and fertilizing ability. However, the molecular mechanisms that govern these maturational events are still poorly defined. This review focuses on recent progress in our understanding of epididymal function including its development, role of the luminal microenvironment in sperm maturation, regulation and novel mechanisms the epididymis utilizes to carry out some of its functions.

METHODS: A systematic search of Pubmed was carried out using the search term 'epididymis'. Articles that were published in the English language until the end of August 2008 and that focused on the specific topics described above were included. Additional papers cited in the primary reference were also included.

RESULTS: While the majority of these findings were the result of studies in animal models, recent studies in the human epididymis are also presented including gene profiling studies to examine regionalized expression in normal epididymides as well as in those from vasectomized patients.

CONCLUSIONS: Significant progress has been made in our understanding of epididymal function providing new insights that ultimately could improve human health. The data also indicate that the human epididymis plays an important role in sperm maturation but has unique properties compared with animal models.

PMID: 19136456 http://www.ncbi.nlm.nih.gov/pubmed/19136456

http://www.ncbi.nlm.nih.gov/pmc/articles/PMC2639084

All You Wanted to Know About Spermatogonia but Were Afraid to Ask

http://www.andrologyjournal.org/cgi/reprint/21/6/776

"During mammalian spermiogenesis, histones at the onset of the differentiation process are gradually replaced by transition proteins and protamines (14,22) and although the replacement is almost complete in most species, in humans ~15% of the mature sperm chromatin remains associated with histone variants"

Sequence-specific packaging of DNA in human sperm chromatin

"The DNA in human sperm chromatin is packaged into nucleoprotamine (approximately 85%) and nucleohistone (approximately 15%). Whether these two chromatin fractions are sequence-specific subsets of the spermatozoon genome is the question addressed in this report. Sequence-specific packaging would suggest distinct structural and functional roles for the nucleohistone and nucleoprotamine in late spermatogenesis or early development or both. After removal of histones with 0.65M NaCl, exposed DNA was cleaved with Bam HI restriction endonuclease and separated by centrifugation from insoluble nucleoprotamine. The DNA sequence distribution of nucleohistone DNA in the supernatant and nucleoprotamine DNA in the pellet was compared by cloning size-selected single-copy sequences and by using the derived clones as probes of nucleohistone DNA and nucleoprotamine DNA. Two clones derived from nucleohistone DNA preferentially hybridized to nucleohistone DNA, and two clones derived from nucleoprotamine DNA preferentially hybridized to nucleoprotamine DNA, which demonstrated the existence of sequence-specific nucleohistone and nucleoprotamine components within the human spermatozoon."

http://www.ncbi.nlm.nih.gov/pubmed/3576213

1996

Partial wave in human seminiferous tubules appears to be a random occurrence

Tissue Cell. 1996 Apr;28(2):127-36.

Johnson L, Mckenzie KS, Snell JR. Source Department of Veterinary Anatomy and Public Health, College Veterinary Medicine, Faculty of Toxicology, Texas A&M University, College Station 77843-4458, USA. LJohnson@VETMED.TAMU.EDU

Abstract

Serial cross sections were evaluated to determine the architectural arrangement of stages among men with varied spermatogenic efficiencies. Using autopsy specimens, glutaraldehyde-perfused testes from men with low or high daily sperm production per g parenchyma were compared. Lobes of testicular parenchyma were teased from connective tissue septa, further fixed in osmium, and embedded such that the straight portions of tubules could be sectioned perpendicularly. Unstained 22 microns serial sections were sectioned optically with Nomarski optics. Paired photomicrographs of each tubular cross section were taken under a 40 x objective, and stages of the spermatogenic cycle were mapped by two observers using Clermont's criteria (Clermont, 1963). For comparison, numbers (1-6) were assigned randomly to the stages, the stages were plotted in two dimensions (length and circumference of tubule) as if the tubule were cut down its length and laid flat, and geometric centers were plotted for each stage. Geometric centers consecutive and/or non-consecutive stages appeared to form an angle down the length of the tubule. When considering helical patterns along the tubule, men with neither low nor high spermatogenic efficiency had a complete wave composed of all six consecutive stages. The helical pattern of geometric centers indicated only 2-4 consecutive stages when the actual values of stages were used or when random numbers were substituted for actual numerical value of stages. The number of consecutive stages in tubules from these men was not different from consecutiveness found when stages were assigned random numbers. Given that no complete wave was found, regardless of spermatogenic efficiency, and that the degree of consecutiveness of stages down a helical pattern in human seminiferous tubules could be generated from random numbers, the arrangement of stages in human seminiferous tubules may simply be a random occurrence.

PMID: 8650667

An analysis of human sperm chromosome aneuploidy

Cytogenet Cell Genet. 1996;74(3):194-200.

Templado C, Márquez C, Munné S, Colls P, Martorell MR, Cieply K, Benet J, Van Kirk V, Navarro J, Estop AM.

Departamento de Biología Celular, Facultad de Medicina, Universidad Autónoma, Barcelona, Spain. Cristina@cc.uab.es Abstract A sperm chromosome analysis of 24 men with normal or balanced karyotypes was carried out to study the frequency of sperm chromosome aneuploidy. A total of 3,446 human sperm complements (36-315 per donor) was analyzed after in vitro penetration of hamster eggs. Two sets of donors were studied at two different centers in the United States (center 1) and Spain (center 2). The frequencies of hyperhaploidy and hypohaploidy in control donors were similar between center 1 (1.9% vs. 7.7%) and center 2 (1.8% vs. 10.3%). In carrier donors there were no significant differences between the two centers in the frequency of hyperhaploidy (0.8% vs. 1.9%), but that of hypohaploidy was significantly higher in center 2 (11.0%) than in center 1 (4.6%). A significant excess of hypohaploid complements, as compared to hyperhaploid complements, was found in both centers in both control and carrier donors. The sex ratio was similar in both centers and did not differ significantly from a 1:1 sex ratio. The larger chromosomes in the complement (1, 2, 3, 4, 5, 7, and 10) presented a significantly lower frequency of hypohaploidy, while some of the smaller chromosomes (13, 19, and 21) showed a higher frequency of hypohaploidy than expected. Chromosome 21 and the sex chromosomes showed an increase in the percentage of hyperhaploidy, as compared to other chromosomes, that was close to statistical significance (P = 0.08). Our results reflect a preferential loss of small chromosomes during slide preparation and suggest that chromosome 21 and the sex chromosomes could be more frequently involved in aneuploidy.

PMID: 8941373

A comparative view of sperm ultrastructure

Fawcett DW. Biol Reprod. 1970 Jun;2:Suppl 2:90-127. PMID: 5521054

http://www.biolreprod.org/content/2/Supplement_2/90.long

Spermatogenesis-Specific Features of the Meiotic Program in Caenorhabditis elegans

(excellent meiosis images) http://www.ncbi.nlm.nih.gov/pmc/articles/PMC2720455/?tool=pmcentrez

Daily spermatozoal production and epididymal spermatozoal reserves of the human male

J Urol. 1980 Aug;124(2):211-5.

Amann RP, Howards SS.

• Testicular and epididymal spermatozoal reserves were determined for 11 healthy men, a vasectomized man and 12 other men.
• For healthy men testis weight (19 testes) averaged 16.9 plus or minus 1.2 gm. and daily spermatozoal production was 4.25 times 10(6) per gm. (range equals 1.4 to 6.3 times 10(6) per gm.). Based on our total sample (23 patients) 67 per cent of the men 20 to 50 years old probably produce between 45 times 10(6) and 207 times 10(6) spermatozoa per day.
• Daily spermatozoal production was normal in 1 vasectomized man. Epididymal reserves of healthy men totaled 182 times 10(6) spermatozoa per epididymis, of which 26 per cent were in the caput, 23 per cent in the corpus and 52 per cent in the cauda. The interval between any previous ejaculation and death was unknown but we assumed that these values are typical for men copulating or masturbating every 1 to 7 days. Extragonadal spermatozoal reserves totaled approximately 440 times 10(6), of which less than 225 times 10(6) would be available for ejaculation in the ductuli deferentia and caudae epididymides.
• Transit time of spermatozoa through the caput, corpus and cauda epididymidis was estimated as 0.72, 0.71 and 1.76 days.
• In a vasectomized man extragonadal reserves totaled 7 times 10(9) spermatozoa or about 75 days of production by the testes.
• Thus, spermatozoal production in man is much less efficient than in other mammals, the extragonadal reserves of spermatozoa are small and maturation of spermatozoa in the caput plus corpus epididymidis occurs in less than 2 days.
• In terms of these quantitative characteristics the reproductive capacity of man is considerably less than that of a rhesus monkey.

PMID: 6772801 http://www.ncbi.nlm.nih.gov/pubmed/6772801

Efficiency of spermatogenesis

Microsc Res Tech. 1995 Dec 1;32(5):385-422.

Johnson L.

Department of Veterinary Anatomy and Public Health, College of Veterinary Medicine, Texas A&M University, College Station 77843-4458, USA. Abstract Spermatogenesis is a process of division and differentiation by which spermatozoa are produced in seminiferous tubules. A measure of efficiency of spermatogenesis is the estimated number of spermatozoa produced per day per gram of testicular parenchyma. This measure is not influenced by species differences in testicular size; however, it is influenced by species differences in the numerical density of germ cells and in the life spans of these cells. Seminiferous tubules are composed of somatic cells (myoid cells and Sertoli cells), and germ cells (spermatogonia, spermatocytes, and spermatids). Activity of these three germ cells divide spermatogenesis into spermatocytogenesis, meiosis, and spermiogenesis, respectively. Spermatocytegenesis involves mitotic cell division to increase the yield of spermatogenesis and to produce stem cells and primary spermatocytes. Meiosis involves duplication and exchange of genetic material and two cell divisions that reduce the chromosome number and yield four spermatids. Spermiogenesis is the differentiation of spherical spermatids into mature spermatids which are released at the luminal free surface as spermatozoa. The spermatogenic cycle is superimposed on the three major divisions of spermatogenesis. Spermatogenesis and germ cell degeneration can be quantified from numbers of germ cells in various steps of development throughout spermatogenesis, and quantitative measures are related to number of spermatozoa in the ejaculate. Germ cell degeneration occurs throughout spermatogenesis; however, the greatest impact occurs during spermatocytogenesis and meiosis. Efficiency of spermatogenesis is related to the amount of germ cell degeneration, pubertal development, season of the year, and aging of humans and animals. Number of Sertoli cells and amount of smooth endoplasmic reticulum of Leydig cells (but not Leydig cell number) are related to efficiency of spermatogenesis. In humans, efficiency of spermatogenesis is reflected in number of spermatogenic stages per cross-section and number of missing generations within each stage; however, the arrangement of stages along the tubular length does not reflect differences in the efficiency of spermatogenesis. In short, spermatogenesis involves both mitotic and meiotic cell divisions and an unsurpassed example of cell differentiation in the production of the spermatozoon, and daily sperm production per g parenchyma is a measure of its efficiency.

PMID: 8563040