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Cite this page: Hill, M.A. (2021, April 12) Embryology Testis Development. Retrieved from https://embryology.med.unsw.edu.au/embryology/index.php/Talk:Testis_Development
XY oocytes of sex-reversed females with a Sry mutation deviate from the normal developmental process beyond the mitotic stage
Sakashita A1,2, Wakai T1, Kawabata Y1, Nishimura C1, Sotomaru Y3, Alavattam KG2, Namekawa SH2, Kono T1.
The fertility of sex-reversed XY female mice is severely impaired by a massive loss of oocytes and failure of meiotic progression. This phenomenon remains an outstanding mystery. We sought to determine the molecular etiology of XY oocyte dysfunction by generating sex-reversed females that bear genetic ablation of Sry, a vital sex determination gene, on an inbred C57BL/6 background. These mutant mice, termed XYsry- mutants, showed severe attrition of germ cells during fetal development, resulting in the depletion of ovarian germ cells prior to sexual maturation. Comprehensive transcriptome analyses of primordial germ cells (PGCs) and postnatal oocytes demonstrated that XYsry- females had deviated significantly from normal developmental processes during the stages of mitotic proliferation. The impaired proliferation of XYsry- PGCs was associated with aberrant β-catenin signaling and the excessive expression of transposable elements. Upon entry to the meiotic stage, XYsry- oocytes demonstrated extensive defects, including the impairment of crossover formation, the failure of primordial follicle maintenance, and no capacity for embryo development. Together, these results suggest potential molecular causes for germ cell disruption in sex-reversed female mice, thereby providing insights into disorders of sex differentiation in humans, such as "Swyer syndrome," in which patients with an XY karyotype present as typical females and are infertile. © The Author(s) 2018. Published by Oxford University Press on behalf of Society for the Study of Reproduction. KEYWORDS: XY PGCs/oocytes; germ cell depletion; infertility of XY female; sex-reversed mice; transcriptome analysis PMID: 30289439
Sex reversal following deletion of a single distal enhancer of Sox9
Gonen N1, Futtner CR2, Wood S1, Garcia-Moreno SA2, Salamone IM2, Samson SC1, Sekido R3, Poulat F4, Maatouk DM5, Lovell-Badge R6. Author information Abstract Cell fate decisions require appropriate regulation of key genes. Sox9, a direct target of SRY, is pivotal in mammalian sex determination. In vivo high-throughput chromatin accessibility techniques, transgenic assays, and genome editing revealed several novel gonadal regulatory elements in the 2-megabase gene desert upstream of Sox9 Although others are redundant, enhancer 13 (Enh13), a 557-base pair element located 565 kilobases 5' from the transcriptional start site, is essential to initiate mouse testis development; its deletion results in XY females with Sox9 transcript levels equivalent to those in XX gonads. Our data are consistent with the time-sensitive activity of SRY and indicate a strict order of enhancer usage. Enh13 is conserved and embedded within a 32.5-kilobase region whose deletion in humans is associated with XY sex reversal, suggesting that it is also critical in humans. Copyright © 2018 The Authors, some rights reserved; exclusive licensee American Association for the Advancement of Science. No claim to original U.S. Government Works. PMID: 29903884 PMCID: PMC6034650 DOI: 10.1126/science.aas9408
Human sex reversal is caused by duplication or deletion of core enhancers upstream of SOX9
Nat Commun. 2018 Dec 14;9(1):5319. doi: 10.1038/s41467-018-07784-9.
Croft B1,2, Ohnesorg T1,3, Hewitt J1,4,5, Bowles J6,7, Quinn A7, Tan J1, Corbin V8, Pelosi E7, van den Bergen J1, Sreenivasan R1,9, Knarston I1,3, Robevska G1, Vu DC10, Hutson J1,3,11, Harley V9, Ayers K1,3, Koopman P7, Sinclair A12,13.
Disorders of sex development (DSDs) are conditions affecting development of the gonads or genitalia. Variants in two key genes, SRY and its target SOX9, are an established cause of 46,XY DSD, but the genetic basis of many DSDs remains unknown. SRY-mediated SOX9 upregulation in the early gonad is crucial for testis development, yet the regulatory elements underlying this have not been identified in humans. Here, we identified four DSD patients with overlapping duplications or deletions upstream of SOX9. Bioinformatic analysis identified three putative enhancers for SOX9 that responded to different combinations of testis-specific regulators. All three enhancers showed synergistic activity and together drive SOX9 in the testis. This is the first study to identify SOX9 enhancers that, when duplicated or deleted, result in 46,XX or 46,XY sex reversal, respectively. These enhancers provide a hitherto missing link by which SRY activates SOX9 in humans, and establish SOX9 enhancer mutations as a significant cause of DSD. PMID: 30552336
|ICD-11 5A81 Testicular dysfunction or testosterone-related disorders|
Testis Histology Links: Labeled Seminiferous tubule 1 | Labeled Seminiferous tubule 2 | Young human overview | Adult human overview | Adult ductus deferens overview | Young human convoluted seminiferous tubules | Young human tunica albuginea | Young human convoluted seminiferous tubule, Sertoli cells, spermatogonia | Young human seminiferous tubule, Leydig cells, spermatogonia, primary spermatocytes, spermatids | Adult human Epididymis | Adult human convoluted seminiferous tubules | Adult human convoluted seminiferous tubules | Adult human high power 1 | Adult human Sertoli cells, spermatogonia, primary spermatocytes, spermatids | Adult human epididymis, ductulus efferens, ductus epididymidis | Adult human epididymis, ductulus efferens, ductus epididymidis | Adult human ductus epididymidis, pseudostratified columnar epithelium, stereocilia | Adult human ductus deferens | Adult human ductus deferens detail | Rabbit convoluted seminiferous tubules | Rabbit convoluted seminiferous tubulesdetail | Histology Stains
Testis Histology Links: File:Seminiferous-tubule-HEx40.jpg | File:Testis_histology_2.jpg | Young human testis, H&E, overview Loupe | Adult human testis, H&E, overview x2 | Adult human ductus deferens, H&E, overview x2 | Young human testis, H&E, convoluted seminiferous tubules, x10 | Young human testis, H&E, tunica albuginea, x20 | Young human testis, H&E, convoluted seminiferous tubule, Sertoli cells, spermatogonia, x40 | Young human testis, H&E, convoluted seminiferous tubule, Leydig cells, spermatogonia, primary spermatocytes, spermatids, x40 | Adult human Epididymis, H&E, overview x4 | Adult human, H&E, convoluted seminiferous tubules, x20 | Adult human, H&E, convoluted seminiferous tubules, x10 | Adult human, H&E, convoluted seminiferous tubules, spermatogonia, primary spermatocytes, spermiogenesis, smooth muscle, x40 | Adult human, H&E, convoluted seminiferous tubules, Sertoli cells, spermatogonia, primary spermatocytes, spermatids, x40 | Adult human, H&E, epididymis, ductulus efferens, ductus epididymidis, x10 | Adult human, H&E, epididymis, ductulus efferens, ductus epididymidis, x20 | Adult human, H&E, ductus epididymidis, pseudostratified columnar epithelium, stereocilia, x40 | Adult human, H&E, ductus deferens, x10 | Adult human, H&E, ductus deferens, pseudostratified columnar epithelium, stereocilia, x40 | Rabbit, PAS, convoluted seminiferous tubules, acrosomes, x20 | Rabbit, PAS, convoluted seminiferous tubules, acrosomes, x100 | Histology Stains
Is there a trans-abdominal testicular descent during the second gestational trimester? Study in human fetuses between 13 and 23 weeks post conception
Int Braz J Urol. 2016 May-Jun;42(3):558-63. doi: 10.1590/S1677-5538.IBJU.2015.0301.
Favorito LA1, Bernardo FO1, Costa SF1, Sampaio FJ1. Author information Abstract OBJECTIVES: To confirm if a real inner descend of testis occurs, correlating the testicular position with fetal parameters and analyzing the position of the testes relative to the internal ring. MATERIAL AND METHODS: Twenty nine human fetuses between 13 and 23 weeks post conception (WPC) were studied. The fetuses were carefully dissected with the aid of a stereoscopic lens with 16/25X magnification and testicular position observed. With the aid of a digital pachymeter the distance between the lower pole of the kidney and the upper extremity of the testis (DK-T) was measured to show the position of the testis. During the dissection we also indicated the position of the testes relative to the internal ring. Means were statistically compared using simple linear regression and the paired T-test. RESULTS: The 58 testes had abdominal position. The DK-T in the right side measured between 0.17 and 1.82cm (mean=0.79cm) and in the left side it was between 0.12 and 1.84cm (mean=0.87cm), without statistically differences (p=0.0557). The linear regression analysis indicated that DK-T in both sides correlated significantly and positively with fetal age. All fetuses with more than 20 WPC, heavier than 350g and with CRL over 22cm had a greater distance than the average DK-T. We xobserved that the 58 testis remains adjacent to the internal ring throughout the period studied. CONCLUSIONS: The testes remains adjacent to the internal ring throughout the period studied, indicating that there is no real trans-abdominal testicular descent during the second gestational trimester. PMID: 27286121 PMCID: PMC4920575
- The moment when testicular descent begins is controversial. Backhouse (2) reports that this process starts at about the 24 th week post-conception, while Heyns (3) and Sampaio&Favorito (4) relate cases where the descent process started as early as the 17th week.
- descent of the testis from the abdomen to the inguinal canal during the first phase of testicular descent
- inner testicular descent was dependent of the gonad growth, involution of mesonephros and the descending septum transversum of the anlage of the diaphragm
- gubernaculum enlarges to hold the testis near the internal ring, regulated by insulin-like-3-hormone (INLS-3) (17, 18). INSL-3 is secreted by the Leydig cells and controls gubernaculum swelling via its receptor, a process resulting in thickening of the gubernaculum because of increases in water, glycosaminoglycan and hyaluronic acid content
Reciprocal Spatiotemporally Controlled Apoptosis Regulates Wolffian Duct Cloaca Fusion
J Am Soc Nephrol. 2018 Mar;29(3):775-783. doi: 10.1681/ASN.2017040380. Epub 2018 Jan 11.
Hoshi M1, Reginensi A2, Joens MS3, Fitzpatrick JAJ3,4,5, McNeill H2, Jain S6,7.
The epithelial Wolffian duct (WD) inserts into the cloaca (primitive bladder) before metanephric kidney development, thereby establishing the initial plumbing for eventual joining of the ureters and bladder. Defects in this process cause common anomalies in the spectrum of congenital anomalies of the kidney and urinary tract (CAKUT). However, developmental, cellular, and molecular mechanisms of WD-cloaca fusion are poorly understood. Through systematic analysis of early WD tip development in mice, we discovered that a novel process of spatiotemporally regulated apoptosis in WD and cloaca was necessary for WD-cloaca fusion. Aberrant RET tyrosine kinase signaling through tyrosine (Y) 1062, to which PI3K- or ERK-activating proteins dock, or Y1015, to which PLCγ docks, has been shown to cause CAKUT-like defects. Cloacal apoptosis did not occur in RetY1062F mutants, in which WDs did not reach the cloaca, or in RetY1015F mutants, in which WD tips reached the cloaca but did not fuse. Moreover, inhibition of ERK or apoptosis prevented WD-cloaca fusion in cultures, and WD-specific genetic deletion of YAP attenuated cloacal apoptosis and WD-cloacal fusion in vivo Thus, cloacal apoptosis requires direct contact and signals from the WD tip and is necessary for WD-cloacal fusion. These findings may explain the mechanisms of many CAKUT.
Copyright © 2018 by the American Society of Nephrology.
KEYWORDS: CAKUT; Wolffian duct; apoptosis; kidney development; nephric duct; ureteric bud PMID: 29326158 PMCID: PMC5827592 DOI: 10.1681/ASN.2017040380
Dehydroepiandrosterone (DHEA) and Its Sulfate (DHEA-S) in Mammalian Reproduction: Known Roles and Novel Paradigms
Vitam Horm. 2018;108:223-250. doi: 10.1016/bs.vh.2018.02.001. Epub 2018 Mar 16.
Chimote BN1, Chimote NM2.
Steroid hormones form an integral part of normal development in mammalian organisms. Cholesterol is the parent compound from which all steroid hormones are synthesized. The product pregnenolone formed from cholesterol serves as precursor for mineralocorticoids, glucocorticoids, as well as dehydroepiandrosterone (DHEA) and its derived sexual hormones. DHEA assumes the prohormone status of a predominant endogenous precursor and a metabolic intermediate in ovarian follicular steroidogenesis. DHEA supplementation has been used to enhance ovarian reserve. Steroids like estradiol and testosterone have long been contemplated to play important roles in regulating meiotic maturation of oocytes in conjunction with gonadotropins. It is known that oocyte priming with estrogen is necessary to develop calcium (Ca2+) oscillations during maturation. Accruing evidence from diverse studies suggests that DHEA and its sulfate (dehydroepiandrosterone sulfate, DHEA-S) play significantly vital role not only as intermediates in androgen and estrogen formation, but may also be the probable 'oocyte factor' and behave as endogenous agonists triggering calcium oscillations for oocyte activation. DHEA/DHEA-S have been reported to regulate calcium channels for the passage of Ca2+ through the oocyte cytoplasm and for maintaining required threshold of Ca2+ oscillations. This role of DHEA/DHEA-S assumes critical significance in assisted reproductive technology and in-vitro fertilization treatment cycles where physical, chemical, and mechanical methods are employed for artificial oocyte activation to enhance fertilization rates. However, since these methods are invasive and may also cause adverse epigenetic modifications; oral or culture-media supplementation with DHEA/DHEA-S provides a noninvasive innate mechanism of in-vitro oocyte activation based on physiological metabolic pathway. KEYWORDS: Calcium oscillations; DHEA; DHEA-S; IVF; Oocyte activation; Oocyte maturation; Steroids PMID: 30029728 DOI: 10.1016/bs.vh.2018.02.001
Influence of fetal Leydig cells on the development of adult Leydig cell population in rats
J Reprod Dev. 2018 Mar 6. doi: 10.1262/jrd.2017-102. [Epub ahead of print]
Su DM1, Feng Y2, Wang L3, Wu YL3, Ge RS4, Ma X5.
Leydig cells are the main endogenous testosterone synthesis cells in the body. Testosterone is an essential hormone in males that affects metabolism, emotion, and pubertal development. However, little is known about the development of Leydig cells and relationship between fetal Leydig cells (FLCs) and adult Leydig cells (ALCs). The aims of this study were to investigate the effect of (FLCs) on ALC development. Our study showed that FLCs in neonatal rat testis can be eliminated by 100 mg/kg ethane dimethane sulfonate (EDS) treatment without affecting the health of newborn rats. Immunohistological results showed that eliminating FLCs led to early re-generation of the ALC population (progenitor Leydig cells [PLCs] and ALCs) accompanied at first by increased and then by decreased serum testosterone, indicating that ALCs which appeared after neonatal EDS treatment were degenerated or had attenuated functions. Our results showed that FLCs were eliminated 4 days after EDS treatment, the ALC population regenerated by 21 days, and serum testosterone levels dramatically decreased at 56 days. Collectively, our results indicate that the ablation of FLCs in neonatal rat results in abnormal development of ALCs. Our study further indicates that abnormal development of Leydig cells in the fetal stage leads to steroid hormone disorders, such as testosterone deficiency, in the adult stage. Therefore, studies of Leydig cell development are important for understanding the pathogenesis of testosterone deficiency or pubertas praecox. KEYWORDS: Adult Leydig cell; Ethane dimethane sulfonate; Fetal Leydig cells; Leydig cell; Rat; Testosterone PMID: 29515056 DOI: 10.1262/jrd.2017-102
Leydig progenitor cells in fetal testis
Mol Cell Endocrinol. 2017 Apr 15;445:55-64. doi: 10.1016/j.mce.2016.12.006. Epub 2016 Dec 8.
Shima Y1, Morohashi KI2.
Testicular Leydig cells play pivotal roles in masculinization of organisms by producing androgens. At least two distinct Leydig cell populations sequentially emerge in the mammalian testis. Leydig cells in the fetal testis (fetal Leydig cells) appear just after initial sex differentiation and induce masculinization of male fetuses. Although there has been a debate on the fate of fetal Leydig cells in the postnatal testis, it has been generally believed that fetal Leydig cells regress and are completely replaced by another Leydig cell population, adult Leydig cells. Recent studies revealed that gene expression patterns are different between fetal and adult Leydig cells and that the androgens produced in fetal Leydig cells are different from those in adult Leydig cells in mice. Although these results suggested that fetal and adult Leydig cells have distinct origins, several recent studies of mouse models support the hypothesis that fetal and adult Leydig cells arise from a common progenitor pool. In this review, we first provide an overview of previous knowledge, mainly from mouse studies, focusing on the cellular origins of fetal Leydig cells and the regulatory mechanisms underlying fetal Leydig cell differentiation. In addition, we will briefly discuss the functional differences of fetal Leydig cells between human and rodents. We will also discuss recent studies with mouse models that give clues for understanding how the progenitor cells in the fetal testis are subsequently destined to become fetal or adult Leydig cells. KEYWORDS: Adult leydig cell; Fetal leydig cell; Progenitor cell; Testis PMID: 27940302 DOI: 10.1016/j.mce.2016.12.006
Risk factors for cryptorchidism
Nat Rev Urol. 2017 Sep;14(9):534-548. doi: 10.1038/nrurol.2017.90. Epub 2017 Jun 27.
Gurney JK1, McGlynn KA2, Stanley J1, Merriman T3, Signal V1, Shaw C1, Edwards R1, Richiardi L4, Hutson J5, Sarfati D1.
Undescended testis - known as cryptorchidism - is one of the most common congenital abnormalities observed in boys, and is one of the few known risk factors for testicular cancer. The key factors that contribute to the occurrence of cryptorchidism remain elusive. Testicular descent is thought to occur during two hormonally-controlled phases in fetal development - between 8-15 weeks (the first phase of decent) and 25-35 weeks gestation (the second phase of descent); the failure of a testis to descend permanently is probably caused by disruptions to one or both of these phases, but the causes and mechanisms of such disruptions are still unclear. A broad range of putative risk factors have been evaluated in relation to the development of cryptorchidism but their plausibility is still in question. Consistent evidence of an association with cryptorchidism exists for only a few factors, and in those cases in which evidence seems unequivocal the factor is likely to be a surrogate for the true causal exposure. The relative importance of each risk factor could vary considerably between mother-son pairs depending on an array of genetic, maternal, placental and fetal factors - all of which could vary between regions. Thus, the role of causative factors in aetiology of cryptorchidism requires further research. PMID: 28654092 PMCID: PMC5815831 DOI: 10.1038/nrurol.2017.90
On the descent of the epididymo-testicular unit, cryptorchidism, and prevention of infertility
Basic Clin Androl. 2017 Nov 14;27:21. doi: 10.1186/s12610-017-0065-8. eCollection 2017.
Abstractin English, French
This comprehensive review provides in-depth coverage of progress made in understanding the molecular mechanisms underlying cryptorchidism, a frequent pathology first described in about 1786 by John Hunter. The first part focuses on the physiology, embryology, and histology of epididymo-testicular descent. In the last 20 years epididymo-testicular descent has become the victim of schematic drawings with an unjustified rejection of valid histological data. This part also includes discussion on the roles of gonadotropin-releasing hormone, fibroblast growth factors, Müllerian inhibiting substance, androgens, inhibin B, and insulin-like 3 in epididymo-testicular descent. The second part addresses the etiology and histology of cryptorchidism as well as the importance of mini-puberty for normal fertility development. A critical view is presented on current clinical guidelines that recommend early orchidopexy alone as the best possible treatment. Finally, by combining classical physiological information and the output of cutting-edge genomics data into a complete picture the importance of hormonal treatment in preventing cryptorchidism-induced infertility is underscored. KEYWORDS: Cryptorchidism; Epididymo-testicular descent; GnRHa-treatment; Infertility; Mini-puberty; RNA sequencing PMID: 29163975 PMCID: PMC5686796 DOI: 10.1186/s12610-017-0065-8
Leydig cell stem cells: Identification, proliferation and differentiation
Mol Cell Endocrinol. 2017 Apr 15;445:65-73. doi: 10.1016/j.mce.2016.10.010. Epub 2016 Oct 12.
Chen H1, Wang Y2, Ge R2, Zirkin BR3.
Adult Leydig cells develop from undifferentiated mesenchymal-like stem cells (stem Leydig cells, SLCs) present in the interstitial compartment of the early postnatal testis. Putative SLCs also have been identified in peritubular and perivascular locations of the adult testis. The latter cells, which normally are quiescent, are capable of regenerating new Leydig cells upon the loss of the adult cells. Recent studies have identified several protein markers to identify these cells, including nestin, PDGFRα, COUP-TFII, CD51 and CD90. We have shown that the proliferation of the SLCs is stimulated by DHH, FGF2, PDGFBB, activin and PDGFAA. Suppression of proliferation occurred with TGFβ, androgen and PKA signaling. The differentiation of the SLCs into testosterone-producing Leydig cells was found to be regulated positively by DHH (Desert hedgehog), lithium-induced signaling and activin; and negatively by TGFβ, PDGFBB, FGF2, Notch and Wnt signaling. DHH, by itself, was found to induce SLC differentiation into LH-responsive steroidogenic cells, suggesting that DHH plays a critical role in the commitment of SLC into the Leydig lineage. These studies, taken together, address the function and regulation of low turnover stem cells in a complex, adult organ, and also have potential application to the treatment of androgen deficiency. Copyright © 2016 Elsevier Ireland Ltd. All rights reserved. KEYWORDS: CD90; COUP-TFII; DHH; Leydig cell; Stem cell
PMID 27743991 PMCID: PMC5346484 [Available on 2018-04-15] DOI: 10.1016/j.mce.2016.10.010
Sertoli Cell Wt1 Regulates Peritubular Myoid Cell and Fetal Leydig Cell Differentiation during Fetal Testis Development
PLoS One. 2016 Dec 30;11(12):e0167920. doi: 10.1371/journal.pone.0167920. eCollection 2016.
Wen Q1,2,3, Wang Y1,2, Tang J1, Cheng CY3, Liu YX1,2.
Sertoli cells play a significant role in regulating fetal testis compartmentalization to generate testis cords and interstitium during development. The Sertoli cell Wilms' tumor 1 (Wt1) gene, which encodes ~24 zinc finger-containing transcription factors, is known to play a crucial role in fetal testis cord assembly and maintenance. However, whether Wt1 regulates fetal testis compartmentalization by modulating the development of peritubular myoid cells (PMCs) and/or fetal Leydig cells (FLCs) remains unknown. Using a Wt1-/flox; Amh-Cre mouse model by deleting Wt1 in Sertoli cells (Wt1SC-cKO) at embryonic day 14.5 (E14.5), Wt1 was found to regulate PMC and FLC development. Wt1 deletion in fetal testis Sertoli cells caused aberrant differentiation and proliferation of PMCs, FLCs and interstitial progenitor cells from embryo to newborn, leading to abnormal fetal testis interstitial development. Specifically, the expression of PMC marker genes α-Sma, Myh11 and Des, and interstitial progenitor cell marker gene Vcam1 were down-regulated, whereas FLC marker genes StAR, Cyp11a1, Cyp17a1 and Hsd3b1 were up-regulated, in neonatal Wt1SC-cKO testes. The ratio of PMC:FLC were also reduced in Wt1SC-cKO testes, concomitant with a down-regulation of Notch signaling molecules Jag 1, Notch 2, Notch 3, and Hes1 in neonatal Wt1SC-cKO testes, illustrating changes in the differentiation status of FLC from their interstitial progenitor cells during fetal testis development. In summary, Wt1 regulates the development of FLC and interstitial progenitor cell lineages through Notch signaling, and it also plays a role in PMC development. Collectively, these effects confer fetal testis compartmentalization.
PMID 28036337 DOI: 10.1371/journal.pone.0167920
- Sertoli cells control peritubular myoid cell fate and support adult Leydig cell development in the prepubertal testis PMID 24803659
Finding their way: themes in germ cell migration
Curr Opin Cell Biol. 2016 Oct;42:128-137. doi: 10.1016/j.ceb.2016.07.007. Epub 2016 Jul 30.
Barton LJ1, LeBlanc MG1, Lehmann R2.
Embryonic germ cell migration is a vital component of the germline lifecycle. The translocation of germ cells from the place of origin to the developing somatic gonad involves several processes including passive movements with underlying tissues, transepithelial migration, cell adhesion dynamics, the establishment of environmental guidance cues and the ability to sustain directed migration. How germ cells accomplish these feats in established model organisms will be discussed in this review, with a focus on recent discoveries and themes conserved across species.
Copyright © 2016 Elsevier Ltd. All rights reserved.
The Formation and Migration of Primordial Germ Cells in Mouse and Man
De Felici M1.
In most multicellular organisms, including mammals, germ cells are at the origin of new organisms and ensure the continuation of the genetic and epigenetic information across the generations.In the mammalian germ line, the primordial germ cells (PGCs) are the precursors of the primary oocytes and prospermatogonia of fetal ovaries and testes, respectively. In mammals such as the primates, in which the formation of the primary oocytes is largely asynchronous and occurs during a relatively long period, PGCs after the arrival into the XX gonadal ridges are termed oogonia which then become primary oocytes when entering into meiotic prophase I. In the fetal testes, germ cells derived from the PGCs after gonad colonization are termed prospermatogonia or gonocytes.One of the most fascinating aspect of the mammalian germline development is that it is probably the first cell lineage to be established in the embryo by epigenetic mechanisms and that these inductive events happen in extraembryonic tissues much earlier that gonad develop inside the embryo proper. Moreover, such events prepare the germ cells for totipotency through genetic and epigenetic regulations of their genome function. How this occurs remained a mystery until short time ago.In this chapter, I will report and discuss the most recent advances in the cellular and molecular mechanisms underlying the formation in extraembryonic tissues and migration of PGCs toward the gonadal ridges made primarily by studies carried out in the mouse with some perspective in the human. Established concepts about these processes will be only summarized when necessary since they are widely described and discussed in many excellent reviews; most of them are cited in the text below.
KEYWORDS: Cell migration; Embryo development; Epigenetics; Gametogenesis; Gonad development; Primordial germ cells
Is the Epididymis a Series of Organs Placed Side By Side?
Biol Reprod. 2016 Apr 27. pii: biolreprod.116.138768. [Epub ahead of print]
Domeniconi RF, Ferreira Souza AC, Xu B, Washington AM, Hinton BT.
The mammalian epididymis is more than a highly convoluted tube divided into four regions: initial segment, caput, corpus and cauda. It is a highly segmented structure with each segment expressing its own and overlapping genes, proteins and signal transduction pathways. Therefore, the epididymis might be viewed as a series of organs placed side by side. In this review we discuss the contributions of septa that divide the epididymis into segments and present hypotheses as to the mechanism by which septa form. The mechanisms of Wolffian duct segmentation are likened to the mechanisms of segmentation of the renal nephron and somites. The renal nephron may provide valuable clues as to how the Wolffian duct is patterned during development, whereas somitogenesis may provide clues as to the timing of the development of each segment. Emphasis is also placed upon how segments are differentially regulated in support of the idea that the epididymis can be considered as multiple organs placed side by side. In particular, one region, the initial segment, which comprises 2 or 4 segments in mice and rats respectively is unique with respect to its regulation and vascularity compared to other segments; loss of development of these segments leads to male infertility. Different ways of thinking of how the epididymis functions may provide new directions and ideas as to how sperm maturation takes place. Copyright 2016 by The Society for the Study of Reproduction. KEYWORDS: Epididymis; Gene expression; Wolffian duct; epididymal segment; male fertility
R-spondin 1/dickkopf-1/beta-catenin machinery is involved in testicular embryonic angiogenesis
PLoS One. 2015 Apr 24;10(4):e0124213. doi: 10.1371/journal.pone.0124213. eCollection 2015.
Caruso M1, Ferranti F2, Corano Scheri K1, Dobrowolny G3, Ciccarone F4, Grammatico P5, Catizone A1, Ricci G6.
Testicular vasculogenesis is one of the key processes regulating male gonad morphogenesis. The knowledge of the molecular cues underlining this phenomenon is one of today's most challenging issues and could represent a major contribution toward a better understanding of the onset of testicular morphogenetic disorders. R-spondin 1 has been clearly established as a candidate for mammalian ovary determination. Conversely, very little information is available on the expression and role of R-spondin 1 during testicular morphogenesis. This study aims to clarify the distribution pattern of R-spondin 1 and other partners of its machinery during the entire period of testicular morphogenesis and to indicate the role of this system in testicular development. Our whole mount immunofluorescence results clearly demonstrate that R-spondin 1 is always detectable in the testicular coelomic partition, where testicular vasculature is organized, while Dickkopf-1 is never detectable in this area. Moreover, organ culture experiments of embryonic male UGRs demonstrated that Dickkopf-1 acted as an inhibitor of testis vasculature formation. Consistent with this observation, real-time PCR analyses demonstrated that DKK1 is able to slightly but significantly decrease the expression level of the endothelial marker Pecam1. The latter experiments allowed us to observe that DKK1 administration also perturbs the expression level of the Pdgf-b chain, which is consistent with some authors' observations relating this factor with prenatal testicular patterning and angiogenesis. Interestingly, the DKK1 induced inhibition of testicular angiogenesis was rescued by the co-administration of R-spondin 1. In addition, R-spondin 1 alone was sufficient to enhance, in culture, testicular angiogenesis.
Embryology and physiology of testicular development and descent
Pediatr Endocrinol Rev. 2014 Feb;11 Suppl 2:206-13.
Virtanen HE, Toppari J.
Sexual differentiation starts with the development of bipotential gonads that further differentiate into testes or ovaries. The fetal testis secretes hormones that guide the differentiation of internal and external sex organs, whereas the fetal ovary remains rather inactive hormonally. Defects in gonadal differentiation or hormone secretion and action result in disorders of sex development (DSD). Testicular descent is a continuum that has often been described to occur in two main phases: the transabdominal phase and the inguinoscrotal phase. The first phase is according to animal studies dependent on Leydig cell-derived insulin-like peptide 3 (INSL3) that induces male-like development of the gubernaculum. This phase is rarely disrupted in man. The inguinoscrotal phase is dependent on androgens, also secreted by Leydig cells. PMID: 24683945
Albumin is synthesized in epididymis and aggregates in a high molecular mass glycoprotein complex involved in sperm-egg fertilization
PLoS One. 2014 Aug 1;9(8):e103566. doi: 10.1371/journal.pone.0103566. eCollection 2014.
Arroteia KF1, Barbieri MF1, Souza GH2, Tanaka H3, Eberlin MN4, Hyslop S5, Alvares LE1, Pereira LA1.
The epididymis has an important role in the maturation of sperm for fertilization, but little is known about the epididymal molecules involved in sperm modifications during this process. We have previously described the expression pattern for an antigen in epididymal epithelial cells that reacts with the monoclonal antibody (mAb) TRA 54. Immunohistochemical and immunoblotting analyses suggest that the epitope of the epididymal antigen probably involves a sugar moiety that is released into the epididymal lumen in an androgen-dependent manner and subsequently binds to luminal sperm. Using column chromatography, SDS-PAGE with in situ digestion and mass spectrometry, we have identified the protein recognized by mAb TRA 54 in mouse epididymal epithelial cells. The ∼65 kDa protein is part of a high molecular mass complex (∼260 kDa) that is also present in the sperm acrosomal vesicle and is completely released after the acrosomal reaction. The amino acid sequence of the protein corresponded to that of albumin. Immunoprecipitates with anti-albumin antibody contained the antigen recognized by mAb TRA 54, indicating that the epididymal molecule recognized by mAb TRA 54 is albumin. RT-PCR detected albumin mRNA in the epididymis and fertilization assays in vitro showed that the glycoprotein complex containing albumin was involved in the ability of sperm to recognize and penetrate the egg zona pellucida. Together, these results indicate that epididymal-derived albumin participates in the formation of a high molecular mass glycoprotein complex that has an important role in egg fertilization.
Building the mammalian testis: origins, differentiation, and assembly of the component cell populations
Genes Dev. 2013 Nov 15;27(22):2409-26. doi: 10.1101/gad.228080.113.
Svingen T, Koopman P. Source Institute for Molecular Bioscience, The University of Queensland, Brisbane QLD 4072, Australia.
Development of testes in the mammalian embryo requires the formation and assembly of several cell types that allow these organs to achieve their roles in male reproduction and endocrine regulation. Testis development is unusual in that several cell types such as Sertoli, Leydig, and spermatogonial cells arise from bipotential precursors present in the precursor tissue, the genital ridge. These cell types do not differentiate independently but depend on signals from Sertoli cells that differentiate under the influence of transcription factors SRY and SOX9. While these steps are becoming better understood, the origins and roles of many testicular cell types and structures-including peritubular myoid cells, the tunica albuginea, the arterial and venous blood vasculature, lymphatic vessels, macrophages, and nerve cells-have remained unclear. This review synthesizes current knowledge of how the architecture of the testis unfolds and highlights the questions that remain to be explored, thus providing a roadmap for future studies that may help illuminate the causes of XY disorders of sex development, infertility, and testicular cancers. KEYWORDS: Leydig cells, Sertoli cells, disorder of sex development, fertility, organogenesis, sex determination
Gadd45g is essential for primary sex determination, male fertility and testis development
PLoS One. 2013;8(3):e58751. doi: 10.1371/journal.pone.0058751. Epub 2013 Mar 13.
Johnen H, González-Silva L, Carramolino L, Flores JM, Torres M, Salvador JM. Source Department of Immunology and Oncology, Centro Nacional de Biotecnología/Consejo Superior de Investigaciones Científicas, Campus Cantoblanco, Madrid, Spain.
In humans and most mammals, differentiation of the embryonic gonad into ovaries or testes is controlled by the Y-linked gene SRY. Here we show a role for the Gadd45g protein in this primary sex differentiation. We characterized mice deficient in Gadd45a, Gadd45b and Gadd45g, as well as double-knockout mice for Gadd45ab, Gadd45ag and Gadd45bg, and found a specific role for Gadd45g in male fertility and testis development. Gadd45g-deficient XY mice on a mixed 129/C57BL/6 background showed varying degrees of disorders of sexual development (DSD), ranging from male infertility to an intersex phenotype or complete gonadal dysgenesis (CGD). On a pure C57BL/6 (B6) background, all Gadd45g(-/-) XY mice were born as completely sex-reversed XY-females, whereas lack of Gadd45a and/or Gadd45b did not affect primary sex determination or testis development. Gadd45g expression was similar in female and male embryonic gonads, and peaked around the time of sex differentiation at 11.5 days post-coitum (dpc). The molecular cause of the sex reversal was the failure of Gadd45g(-/-) XY gonads to achieve the SRY expression threshold necessary for testes differentiation, resulting in ovary and Müllerian duct development. These results identify Gadd45g as a candidate gene for male infertility and 46,XY sex reversal in humans.
Nationwide Prevalence of Groin Hernia Repair
PLoS ONE 8(1): e54367. doi:10.1371/journal.pone.0054367 (2013)
Burcharth J, Pedersen M, Bisgaard T, Pedersen C, Rosenberg J
Groin hernia repair is a commonly performed surgical procedure in the western world but large-scaled epidemiologic data are sparse. Large-scale data on the occurrence of groin hernia repair may provide further understanding to the pathophysiology of groin hernia development. This study was undertaken to investigate the age and gender dependent prevalence of groin hernia repair.
Dicer1 ablation in the mouse epididymis causes dedifferentiation of the epithelium and imbalance in sex steroid signaling
PLoS One. 2012;7(6):e38457. Epub 2012 Jun 6.
Björkgren I, Saastamoinen L, Krutskikh A, Huhtaniemi I, Poutanen M, Sipilä P. Source Department of Physiology, Institute of Biomedicine, University of Turku, Turku, Finland. Abstract
BACKGROUND: The postnatal development of the epididymis is a complex process that results in a highly differentiated epithelium, divided into several segments. Recent studies indicate a role for RNA interference (RNAi) in the development of the epididymis, however, the actual requirement for RNAi has remained elusive. Here, we present the first evidence of a direct need for RNAi in the differentiation of the epididymal epithelium. METHODOLOGY/PRINCIPAL FINDINGS: By utilizing the Cre-LoxP system we have generated a conditional knock-out of Dicer1 in the two most proximal segments of the mouse epididymis. Recombination of Dicer1, catalyzed by Defb41(iCre/wt), took place before puberty, starting from 12 days postpartum. Shortly thereafter, downregulation of the expression of two genes specific for the most proximal epididymis (lipocalin 8 and cystatin 8) was observed. Following this, segment development continued until week 5 at which age the epithelium started to regress back to an undifferentiated state. The dedifferentiated epithelium also showed an increase in estrogen receptor 1 expression while the expression of androgen receptor and its target genes; glutathione peroxidase 5, lipocalin 5 and cysteine-rich secretory protein 1 was downregulated, indicating imbalanced sex steroid signaling. CONCLUSIONS/SIGNIFICANCE: At the time of the final epididymal development, Dicer1 acts as a regulator of signaling pathways essential for maintaining epithelial cell differentiation.
The biology of the desmosome-like junction a versatile anchoring junction and signal transducer in the seminiferous epithelium
Int Rev Cell Mol Biol. 2011;286:223-69.
Lie PP, Cheng CY, Mruk DD. Source Population Council, Center for Biomedical Research, New York, New York, USA. Abstract Mammalian spermatogenesis, a complex process that involves the movement of developing germ cells across the seminiferous epithelium, entails extensive restructuring of Sertoli-Sertoli and Sertoli-germ cell junctions. Presently, it is not entirely clear how zygotene spermatocytes gain entry into the adluminal compartment of the seminiferous epithelium, which is sealed off from the systemic circulation by the Sertoli cell component of the blood-testis barrier, without compromising barrier integrity. To begin to address this question, it is critical that we first have a good understanding of the biology and the regulation of different types of Sertoli-Sertoli and Sertoli-germ cell junctions in the testis. Supported by recent studies in the field, we discuss how crosstalk between different types of junctions contributes to their restructuring during germ cell movement across the blood-testis barrier. We place special emphasis on the emerging role of desmosome-like junctions as signal transducers during germ cell movement across the seminiferous epithelium.
Copyright © 2011 Elsevier Inc. All rights reserved.
Prenatal testosterone and dihydrotestosterone exposure disrupts ovine testes development
Reproduction. 2011 Apr 14. [Epub ahead of print]
Bormann CL, Smith GD, Padmanabhan V, Lee TM. Source C Bormann, OB/GYN, University of Wisconsin, Madison, 53792, United States.
Androgens play important roles during the first trimester of intrauterine life, coinciding with genital tract differentiation, during virilization and maintenance of secondary male characteristics and during initiation of spermatogenesis. Little is known about the impact of inappropriate exposure to excess androgens during fetal development on male sexual maturation and reproduction. The objectives of this study were to determine the effects of prenatal 5α-dihydrotestosterone (DHT) and testosterone treatment during ovine sexual differentiation on post-pubertal testicular formation and subsequent potential for fertility as assessed by epididymal sperm characteristics. Rams prenatally treated with testosterone exhibited increased testicular weight relative to age-matched controls (C) and prenatal DHT-treated rams (P<0.05), as well as elevated total and free testosterone concentrations compared to DHT-treated rams (P=0.07 and P<0.05, respectively). The percentage of progressively motile sperm from the epididymis was significantly reduced in prenatal DHT-treated but not testosterone-treated rams compared to C rams (P<0.05). The testosterone-treated rams had a greater number of germ cell layers than DHT-treated rams, but comparable to the controls. Prenatal testosterone-treated rams had significantly larger seminiferous tubule diameter, and lumen diameter compared to prenatal DHT-treated (P<0.05). Significantly more prenatal DHT- and testosterone-treated rams (P<0.05) had occluded tubule lumen than C rams. Findings from this study demonstrate that exposure to excess testosterone/DHT during male fetal sexual differentiation have differential effects on post-pubertal testicular size, seminiferous tubule size and function, sperm motility, and testosterone concentrations.
How do you get six meters of epididymis inside a human scrotum?
J Androl. 2011 Nov-Dec;32(6):558-64. Epub 2011 Mar 25.
Hinton BT, Galdamez MM, Sutherland A, Bomgardner D, Xu B, Abdel-Fattah R, Yang L. Source Department of Cell Biology, University of Virginia Health System, Charlottesville, VA 22908, USA. firstname.lastname@example.org Abstract It is very clear that the epididymis plays a crucial role in the maturation of spermatozoa, and without a fully developed and functional epididymis, male infertility will result. We are especially interested in understanding the mechanisms that regulate the development of this important organ because disruptions to epididymal function will also arise as a consequence of abnormal development. Very little is known either of the process of epididymal development or the nature and causes of congenital defects that lead to male infertility. A major event during Wolffian/epididymal duct embryonic development is elongation and coiling and this short review outlines potential mechanisms by which these events occur. It is hypothesized that elongation is the result of cell proliferation coupled with directed cell rearrangements, the later regulated by the planar cell polarity signaling pathway. Coiling proceeds in a proximal to distal manner, with three-dimensional coiling beginning approximately embryonic day 16.5 to 18.5 in the mouse. The exact mechanisms of coiling are not known but we hypothesize that it involves an interaction between the Wolffian duct epithelium and the surrounding mesenchyme cells, such that the extracellular matrix is remodeled to allow coiling and growth of the duct. Cell proliferation in the Wolffian duct appears to be dependent on the presence of androgens and mesenchymal factors during embryonic development, but lumicrine factors play an additional role during postnatal development.
Gubernacular development in the mouse is similar to the rat and suggests that the processus vaginalis is derived from the urogenital ridge and is different from the parietal peritoneum
J Pediatr Surg. 2011 Sep;46(9):1804-12.
Buraundi S, Balic A, Farmer PJ, Southwell BR, Hutson JM. Source Douglas Stephens Surgical Research Laboratory, Murdoch Childrens Research Institute, Melbourne 3052, Australia.
BACKGROUND: Gubernacular development and testicular descent have been studied most extensively in rat models, but new transgenic mouse models require a deep understanding of normal mouse development so that results can be extrapolated to the human. We aimed to compare gubernacular anatomy during development in the mouse with that of the rat. METHODS: Time-mated mice (C57BL/6) and Sprague-Dawley rats were used to collect male fetuses at embryonic (E) days E13, E14, E15, E17, E18, and E19 and neonates at postnatal (P) days P0 and P2. Fetuses and newborn were processed for serial sections (sagittal, transverse, and coronal) and stained with hematoxylin and eosin, muscle markers (embryonic myosin, desmin), a neuronal marker (Tuj1), a mitotic marker (Ki67), and keratin marker to label epithelium. RESULTS: Early development of cremaster in the mouse was related to transversus abdominis muscle, but not internal oblique muscle (as in rats), and forms a monolaminar cremaster layer. There is close association between the regressing inguinal mammary bud and the gubernaculum in the mouse at E13. The peritoneal surface of the processus vaginalis (PV) covering the gubernaculum and epididymis was morphologically distinct from the remaining parietal peritoneum throughout development. CONCLUSIONS: Gubernacular development in mouse is similar to that in the rat except for certain structures, such as cremaster muscle. The PV seems to be derived from the surface of the urogenital ridge, separate from the remaining parietal peritoneum. This study suggests that the PV has evolved to aid testicular descent in this species, rather than a nondescript diverticulum of parietal peritoneum. Copyright © 2011 Elsevier Inc. All rights reserved.
Hormonal regulation of male germ cell development
J Endocrinol. 2010 May;205(2):117-31. Epub 2010 Feb 9.
Ruwanpura SM, McLachlan RI, Meachem SJ. Source Prince Henry's Institute of Medical Research, Clayton, Victoria 3168, Australia.
Over the past five decades, intense research using various animal models, innovative technologies notably genetically modified mice and wider use of stereological methods, unique agents to modulate hormones, genomic and proteomic techniques, have identified the cellular sites of spermatogenesis, that are regulated by FSH and testosterone. It has been established that testosterone is essential for spermatogenesis, and also FSH plays a valuable role. Therefore understanding the basic mechanisms by which hormones govern germ cell progression are important steps towards improved understating of fertility regulation in health diseases.
Figure 4 A diagram summarizing the sites, cellular mechanisms, and molecular pathways underpinning gonadotrophin (FSH and testosterone (T)) actions on human spermatogenesis based on the findings from the literature (in black) and unsolved issues (in red). http://joe.endocrinology-journals.org/cgi/content/full/205/2/117/FIG4
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 Apr;73(4):241-78.
Hermo L, Pelletier RM, Cyr DG, Smith CE. Source Department of Anatomy and Cell Biology, Faculty of Medicine, McGill University, Montreal, Quebec, Canada H3A 2B2. email@example.com
Spermatogenesis, a study of germ cell development, is a long, orderly, and well-defined process occurring in seminiferous tubules of the testis. It is a temporal event whereby undifferentiated spermatogonial germ cells evolve into maturing spermatozoa over a period of several weeks. Spermatogenesis is characterized by three specific functional phases: proliferation, meiosis, and differentiation, and it involves spermatogonia, spermatocytes, and spermatids. Germ cells at steps of development form various cellular associations or stages, with 6, 12, and 14 specific stages being identified in human, mouse, and rat, respectively. The stages evolve over time in a given area of the seminiferous tubule forming a cycle of the seminiferous epithelium that has a well-defined duration for a given species. In this part, we discuss the proliferation and meiotic phase whereby spermatogonia undergo several mitotic divisions to form spermatocytes that undergo two meiotic divisions to form haploid spermatids. In the rat, spermatogonia can be subdivided into several classes: stem cells (A(s)), proliferating cells (A(pr), A(al)), and differentiating cells (A(1)-A(4), In, B). They are dependent on a specific microenvironment (niche) contributed by Sertoli, myoid, and Leydig cells for proper development. Spermatogonia possess several surface markers whereby they can be identified from each other. During meiosis, spermatocytes undergo chromosomal pairing, synapsis, and genetic exchange as well as transforming into haploid cells following meiosis. The meiotic cells form specific structural entities such as the synaptonemal complex and sex body. Many genes involved in spermatogonial renewal and the meiotic process have been identified and shown to be essential for this event.
Copyright 2009 Wiley-Liss, Inc.
Drug transporters, the blood-testis barrier, and spermatogenesis
J Endocrinol. 2011 Mar;208(3):207-23. Epub 2010 Dec 6.
Su L, Mruk DD, Cheng CY. Source The Mary M Wohlford Laboratory for Male Contraceptive Research, Center for Biomedical Research, Population Council, New York, New York 10065, USA.
The blood-testis barrier (BTB), which is created by adjacent Sertoli cells near the basement membrane, serves as a 'gatekeeper' to prohibit harmful substances from reaching developing germ cells, most notably postmeiotic spermatids. The BTB also divides the seminiferous epithelium into the basal and adluminal (apical) compartment so that postmeiotic spermatid development, namely spermiogenesis, can take place in a specialized microenvironment in the apical compartment behind the BTB. The BTB also contributes, at least in part, to the immune privilege status of the testis, so that anti-sperm antibodies are not developed against antigens that are expressed transiently during spermatogenesis. Recent studies have shown that numerous drug transporters are expressed by Sertoli cells. However, many of these same drug transporters are also expressed by spermatogonia, spermatocytes, round spermatids, elongating spermatids, and elongated spermatids, suggesting that the developing germ cells are also able to selectively pump drugs 'in' and/or 'out' via influx or efflux pumps. We review herein the latest developments regarding the role of drug transporters in spermatogenesis. We also propose a model utilized by the testis to protect germ cell development from 'harmful' environmental toxicants and xenobiotics and/or from 'therapeutic' substances (e.g. anticancer drugs). We also discuss how drug transporters that are supposed to protect spermatogenesis can work against the testis in some instances. For example, when drugs (e.g. male contraceptives) that can perturb germ cell adhesion and/or maturation are actively pumped out of the testis or are prevented from entering the apical compartment, such as by efflux pumps.
The evolutionary history of testicular externalization and the origin of the scrotum
J Biosci. 2010 Mar;35(1):27-37.
Kleisner K, Ivell R, Flegr J. Source Department of Philosophy and History of Science, Charles University, Vinicna 7, 128 44 Prague, Czech Republic. firstname.lastname@example.org
This paper re-examines the evolution of the scrotum and testicular descent in the context of the recent phylogeny of mammals. The adaptive significance of testicular descent and scrotality is briefly discussed. We mapped four character states reflecting the position of testes and presence of scrotum onto recent mammalian phylogeny. Our results are interpreted as follows: as to the presence of testicondy in Monotremata and most of Atlantogenata, which represent the basal group of all eutherians, we argue that primary testicondy represents a plesiomorphic condition for Eutheria as well as for all mammals. This is in opposition to the previous hypothesis of Werdelin and Nilsonne that the scrotum may have evolved before the origin of mammals and then repeatedly disappeared in many groups including monotremes. We suggest that the scrotum evolved at least twice during the evolutionary history of mammals, within Marsupialia and Boreoeutheria, and has subsequently been lost by many groups; this trend is especially strong in Laurasiatheria. We suggest that the recent diversity in testicular position within mammals is the result of multiple selection pressures stemming from the need to provide conditions suitable for sperm development and storage, or to protect the male gonads from excessive physical and physiological disturbance.
A deficiency of lunatic fringe is associated with cystic dilation of the rete testis
Reproduction. 2009 Jan;137(1):79-93. Epub 2008 Sep 18.
Hahn KL, Beres B, Rowton MJ, Skinner MK, Chang Y, Rawls A, Wilson-Rawls J. Source School of Life Sciences, Arizona State University, Tempe, Arizona 85287-4501, USA.
Lunatic fringe belongs to a family of beta1-3 N-acetyltransferases that modulate the affinity of the Notch receptors for their ligands through the elongation of O-fucose moieties on their extracellular domain. A role for Notch signaling in vertebrate fertility has been predicted by the intricate expression of the Notch receptors and their ligands in the oocyte and granulosa cells of the ovary and the spermatozoa and Sertoli cells of the testis. It has been demonstrated that disruption of Notch signaling by inactivation of lunatic fringe led to infertility associated with pleiotropic defects in follicle development and meiotic maturation of oocytes. Lunatic fringe null males were found to be subfertile. Here, we report that gene expression data demonstrate that fringe and Notch signaling genes are expressed in the developing testis and the intratesticular ductal tract, predicting roles for this pathway during embryonic gonadogenesis and spermatogenesis. Spermatogenesis was not impaired in the majority of the lunatic fringe null males; however, spermatozoa were unilaterally absent in the epididymis of many mice. Histological and immunohistochemical analysis of these testes revealed the development of unilateral cystic dilation of the rete testis. Tracer dye experiments confirm a block in the connection between the rete testis and the efferent ducts. Further, the dye studies demonstrated that many lunatic fringe mutant males had partial blocks of the connection between the rete testis and the efferent ducts bilaterally.
New insights into epididymal biology and function
Hum Reprod Update. 2009 Mar-Apr;15(2):213-27. Epub 2009 Jan 8.
Department of Cell Biology and Biochemistry, Texas Tech University Health Sciences Center, Lubbock, 79430, USA. email@example.com 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.
Phenotypic plasticity of mouse spermatogonial stem cells
PLoS One. 2009 Nov 19;4(11):e7909.
Morimoto H, Kanatsu-Shinohara M, Takashima S, Chuma S, Nakatsuji N, Takehashi M, Shinohara T. Source Department of Molecular Genetics, Graduate School of Medicine, Kyoto University, Kyoto, Japan.
BACKGROUND: Spermatogonial stem cells (SSCs) continuously undergo self-renewal division to support spermatogenesis. SSCs are thought to have a fixed phenotype, and development of a germ cell transplantation technique facilitated their characterization and prospective isolation in a deterministic manner; however, our in vitro SSC culture experiments indicated heterogeneity of cultured cells and suggested that they might not follow deterministic fate commitment in vitro.
METHODOLOGY AND PRINCIPAL FINDINGS: In this study, we report phenotypic plasticity of SSCs. Although c-kit tyrosine kinase receptor (Kit) is not expressed in SSCs in vivo, it was upregulated when SSCs were cultured on laminin in vitro. Both Kit(-) and Kit(+) cells in culture showed comparable levels of SSC activity after germ cell transplantation. Unlike differentiating spermatogonia that depend on Kit for survival and proliferation, Kit expressed on SSCs did not play any role in SSC self-renewal. Moreover, Kit expression on SSCs changed dynamically once proliferation began after germ cell transplantation in vivo.
CONCLUSIONS/SIGNIFICANCE: These results indicate that SSCs can change their phenotype according to their microenvironment and stochastically express Kit. Our results also suggest that activated and non-activated SSCs show distinct phenotypes.
- Aging of the human ovary and testis. Perheentupa A, Huhtaniemi I. Mol Cell Endocrinol. 2009 Feb 5;299(1):2-13. Epub 2008 Nov 18. Review. PMID 19059459
- Epithelial-mesenchymal crosstalk in Wolffian duct and fetal testis cord development. Archambeault DR, Tomaszewski J, Joseph A, Hinton BT, Yao HH. Genesis. 2009 Jan;47(1):40-8. Review. PMID 18979542
- Mixed signals: development of the testis. Cool J, Capel B. Semin Reprod Med. 2009 Jan;27(1):5-13. Epub 2009 Feb 5. Review. PMID 19197800
Applied anatomic study of testicular veins in adult cadavers and in human fetuses
Int Braz J Urol. 2007 Mar-Apr;33(2):176-80.
Favorito LA, Costa WS, Sampaio FJ. Source Urogenital Research Unit, State University of Rio de Janeiro, Rio de Janeiro, Brazil. firstname.lastname@example.org Abstract OBJECTIVES: Analyze the anatomic variations of the testicular veins in human cadavers and fetuses. MATERIALS AND METHODS: One hundred male adult cadavers and 24 fetuses were studied. Four anatomic aspects were considered: 1) Number of testicular veins, 2) The local of vein termination, 3) Type and number of collaterals present and 4) Testicular vein termination angle. RESULTS: Cadavers - Right side - One testicular vein occurred in 85% and 2 veins in 5% of the cases. There were communicating veins with the colon in 21% of the cases. Left side - One testicular vein occurred in 82%, two veins in 15%, three veins in 2% and four veins in 1% of the cases. There were communicating veins with the colon in 31% of the cases. Fetuses - Right side - One testicular vein occurred in all cases. This vein drained to the vena cava in 83.3% of the cases, to the junction of the vena cava with the renal vein in 12.5% and to the renal vein in 4.2%. There were communicating veins with the colon in 25% of the cases. Left side - One testicular vein occurred in 66.6% of the cases, and 2 veins in occurred 33.3%. Communicating veins with the colon were found in 41.6% of the cases. CONCLUSION: The testicular vein presents numeric variations and also variations in its local of termination. In approximately 30% of the cases, there are collaterals that communicate the testicular vein with retroperitoneal veins. These anatomic findings can help understanding the origin of varicocele and its recurrence after surgical interventions.
Ultrastructural morphodynamics of human Sertoli cells during testicular differentiation
Ital J Anat Embryol. 2001;106(2 Suppl 2):163-71.
Heyn R, Makabe S, Motta PM. Source Department of Anatomy, University of Rome La Sapienza, Italy. Rose.Heyn@uniroma1.it
Our study reviews and ultrastructurally characterises human pre-Sertoli cells between the 6th and the 20th week of gestation by means of integrated light microscopy, transmission electron microscopy and high resolution scanning electron microscopy (standard or following ODO maceration). The morphofunctional differentiation of Sertoli cells defines testicular differentiation. These somatic cells are mostly of mesonephric origin and can be first morphologically recognised in 7 week-old embryos altogether with the formation of testicular cords. The latter organise as primordial germ cells surrounded by pre-Sertoli cells. Due to the great synthetic activity of pre-Sertoli cells the rough endoplasmic reticulum develops. The basal lamina of the cords becomes distinguishable at 7 to 8 weeks of gestation. Both prespermatogonia and pre-Sertoli cells actively proliferate but the latter greatly outnumber prespermatogonia. Many interdigitations and cytoplasmic processes are observed between neighbouring pre-Sertoli cells. Due to cell proliferation a sort of compartmentalisation is established inside the cords in which pre-Sertoli cells tend to localise closer to the basal membrane embracing prespermatogonia with long and thin cytoplasmic processes. One of the main typical features of differentiating pre-Sertoli cells is the irregular nucleus and the prominent nucleolus. When the embryo is 14 to 20 weeks-old pre-Sertoli cells maintain their general morphology whereas the most significant change is the maximum development of Leydig cells. Testicular cords do not show any lumen at all so they cannot be termed "tubules".
The testicular descent in human. Origin, development and fate of the gubernaculum Hunteri, processus vaginalis peritonei, and gonadal ligaments
Adv Anat Embryol Cell Biol. 2000;156:III-X, 1-98.
Barteczko KJ, Jacob MI.
Abteilung für Anatomie und Embryologie, Ruhr-Universität Bochum, Germany. email@example.com
Testicular descent has to be divided into the turn-out of the testis and epididymis from the abdomen proper and an inner abdominal descent of genital organs. Both events are closely related to and depend on the development and reorganisation of ligaments, mainly the gubernaculum Hunteri. These seemingly unambiguous events are controversially described since the first description of the gubernaculum, and results and specifics of other species were intermingled with data from humans, thus giving more confusion than lucidity in this important step of gonadal development. Here, we concentrate on human embryos, chronologically investigated by serial sections, scanning electron microscopy, three-dimensional reconstructions, microdissection and immunohistochemistry. The first question to be answered was whether a real inner descent of gonads occurs. We demonstrated this inner descent by showing the relations of the gonads, mesonephros, cranial mesonephric ligament and the anlage of the diaphragm with the vertebral segments. No explosion-like increase in certain vertebral segments was observed which might simulate a gonadal descent. The inner descent is coupled with the growth of the gonad (ovary or testis), the involution of mesonephros, the descending septum transversum or the anlage of the diaphragm, and the intercalated cranial mesonephric ligament. This ligament always inserts medially at the border between the gonad and mesonephros in close relationship to the abdominal ostium of the müllerian duct, a region where hydatides often occur. In contrast to the testes, the ovaries arrive very early--20-25 mm CRL--at their definitive position of S2/3 (level of linea terminalis pelvis), yet, are transversally oriented. The cranial gonadal ligament does not exhibit notable increase in length during inner descent. It does not contain blood vessels. While regressing in both sexes, it will be replaced by the plica formed by the ovarian vessels, that is the suspensorium ligament of the ovary as known in adults. The second point to be investigated was the origin, development, structure and fate of the gubernaculum Hunteri as well as the processus vaginalis peritonei. Their arrangement and composition is crucial for testicular descent. We discriminated five phases of their development and differentiation. Phase I characterises the early development of the gubernaculum of stage 14 CC (5-7 mm CRL) embryos. It arises as conus inguinalis and connects the abdominal wall lateral to the umbilical artery with the caudal part of the mesonephric fold. It is in this early stage that the localisation of the inner inguinal ring is defined. In phase II, stage 20-23 CC (21-30 mm CRL), three parts of the gubernaculum--abdominal, interstitial and subcutaneous--can be distinguished. The processus vaginalis peritonei appears with its dorsal layer firmly adhering to the ventral side of the gubernaculum. The gubernaculum inserts cranially into the mesenchyme of the genital ducts at their crossing-over. Opposite to it, but at some distance, a ligament connects the caudal pole of the testis with the dorsal mesenchyme of the genital ducts. In female embryos, the analge of the ovarian ligament appears as a U-shaped, double peritoneal fold. Phase II is subdivided in phase IIa (32-55 mm CRL), characterised by an enormous increase in length and volume of the gubernaculum and also an enlargement of the processus vaginalis peritonei. In phase III, sex-specific differences in gonadal position and gubernacular structure can be observed for the first time. Testes increase in volume and come close to the mesenchyme of the genital ducts. The caudal pole of the testis overlaps both ducts. We also subdivide this phase into phase IIIa (about 100 mm CRL) where two very important events occur in male foetuses: 1, the swelling of the gubernaculum, and 2, the gliding of the testis across the genital ducts. This gliding is permitted by both, the regression of the müllerian duct and t
Posttesticular development of spermatozoa of the tammar wallaby (Macropus eugenii)
J Anat. 1997 Feb;190 ( Pt 2):275-88.
Setiadi D, Lin M, Rodger JC. Department of Biological Sciences, University of Newcastle, NSW, Australia.
Abstract Tammar wallaby spermatozoa undergo maturation during transit through the epididymis. This maturation differs from that seen in eutherian mammals because in addition to biochemical and functional maturation there are also major changes in morphology, in particular formation of the condensed acrosome and reorientation of the sperm head and tail. Of spermatozoa released from the testes, 83% had a large immature acrosome. By the time spermatozoa reached the proximal cauda epididymis 100% of sperm had condensed acrosomes. Similarly 86% of testicular spermatozoa had immature thumb tack or T shape head-tail orientation while only 2% retained this immature morphology in the corpus epididymis. This maturation is very similar to that reported for the common brush tail possum, Trichosurus vulpecula. However, morphological maturation occurred earlier in epididymal transit in the tammar wallaby. By the time spermatozoa had reached the proximal cauda epididymis no spermatozoa had an immature acrosome and thumbtack orientation. Associated with acrosomal maturation was an increase in acrosomal thiols and the formation of disulphides which presumably account for the unusual stability of the wallaby sperm acrosome. The development of motility and progressive motility of tammar wallaby spermatozoa is similar to that of other marsupials and eutherian mammals. Spermatozoa are immotile in the testes and the percentage of motile spermatozoa and the strength of their motility increases during epididymal transit. During passage through the caput and corpus epididymis, spermatozoa first became weakly motile in the proximal caput and then increasingly progressively motile through the corpus epididymis. Tammar wallaby spermatozoa collected from the proximal cauda epididymis had motility not different from ejaculated spermatozoa. Ultrastructural studies indicated that acrosomal condensation involved a complex infolding of the immature acrosome. At spermiation the acrosome of tammar wallaby spermatozoa was a relatively large flat or concave disc which projected laterally and anteriorly beyond the limits of the nucleus. During transit of the epididymal caput and proximal corpus the lateral projections folded inwards to form a cup like structure the sides of which eventually met and fused. The cavity produced by this fusion was lost as the acrosome condensed to its mature form as a small button-like structure contained within the depression on the anterior end of the nucleus. During this process the dorsal surface of the immature acrosome and its outer acrosomal membrane and overlying plasma membrane were engulfed into the acrosomal matrix. This means that the dorsal surface of the acrosomal region of the testicular tammar wallaby sperm head is a transient structure. The dorsal acrosomal surface of the mature spermatozoon appears ultrastructurally to be the relocated ventral surface of the acrosomal projections which previously extended out beyond the acrosomal depression on the dorsal surface of the nucleus of the immature spermatozoon.
Sertoli cells of the mouse testis originate from the coelomic epithelium
Dev Biol. 1998 Nov 15;203(2):323-33.
Karl J1, Capel B.
During mouse development, the gonad begins to form shortly before 10. 5 days postcoitum (dpc) on the ventromedial side of the mesonephros. The XY gonad consists of germ cells and somatic cells. The origin of the germ cells is clearly established; however, the origin of the somatic cells, especially the epithelial supporting cell lineages, called Sertoli cells, is still unclear. Sertoli cells are the first somatic cell type to differentiate in the testis and are thought to express Sry, the male sex-determining gene, and to play a crucial role in directing testis development. Previous data have suggested that the somatic cells of the gonad may arise from the mesonephric tubules, the mesonephric mesenchyme, or the coelomic epithelium. Immunohistochemical staining of the gonad at 11.5 dpc showed that the basement membrane barrier under the coelomic epithelium is discontinuous, suggesting that cells in the coelomic epithelium at this stage might move inward. To test this possibility directly, cells of the coelomic epithelium were labeled using the fluorescent lipophilic dye, DiI. We show that when labeled at tail somite 15-17 stages, corresponding to 11.2-11.4 dpc, the coelomic epithelial cells of both sexes migrated into the gonad. In XY gonads, the migrating coelomic epithelial cells became Sertoli cells, as well as interstitial cells. This ability of the coelomic epithelium to give rise to Sertoli cells was developmentally regulated. When labeled at tail somite 18-20 stages, corresponding to 11.5-11.7 dpc, the coelomic epithelial cells no longer became Sertoli cells. Instead, cells that migrated into the gonad stayed outside testis cords, in the interstitium. Migration gradually decreased and ceased by tail somite 30 stage, corresponding to 12.5 dpc, after testis cords had formed and the basement membrane layer underlying the coelomic epithelium had thickened to form the tunica albuginea. In XX gonads, coelomic epithelial cells also migrated into the gonad, but there was no obvious fate restriction during the same developmental period. Taken together, our data show that the coelomic epithelium is a source of Sertoli cells as well as other somatic cells of the gonad in the developing mouse testis. Copyright 1998 Academic Press.
The gubernaculum during testicular descent in the human fetus
J Anat. 1987 Aug;153:93-112.
This study of 178 male human fetuses and infants demonstrates that descent of the testis through the inguinal canal is a rapid process, with 75% of testes descending between 24 and 28 weeks of gestation. The gubernaculum is a cylindrical, gelatinous structure attached cranially to the testis and epididymis. While the testis is in the abdomen, the caudal tip of the gubernaculum is firmly attached to the region of the inguinal canal. In a few fetuses prior to descent the globular tip of the gubernaculum can be seen bulging through the external inguinal ring, covered by superficial fascia, with no macroscopically discernible extensions to the scrotum or any other area. Once the testis has passed through the inguinal canal, the bulbous lower tip of the gubernaculum is no longer firmly attached to any structure, nor does it extend to the bottom of the scrotum. Histologically the gubernaculum consists of undifferentiated mesenchymatous tissue. Prior to descent of the testis, there is an increase in the length of the intra-abdominal gubernaculum. The wet mass of the gubernaculum relative to the fetal mass increases rapidly prior to descent, while the relative wet mass of the testis remains constant during this period. There is also an increase in the wet/dry mass ratio of the gubernaculum, denoting an increase in its water content prior to descent. This indicates that a combination of growth processes is responsible for testicular descent, with the increase in the size of the gubernaculum playing the most important role in passage of the testis through the inguinal canal.
Abstracts of Lectures on the Development and Transition of the Testicles, Normal and Abnormal C. B. Lockwood Br Med J. 1887 Mar 19; 1(1368): 610–612. PMCID: PMC2534254 SummaryPage BrowsePDF–1.0MCitation Select item 2534218 2824. Abstracts of Lectures on the Development and Transition of the Testicles, Normal and Abnormal C. B. Lockwood Br Med J. 1887 Mar 5; 1(1366): 500–502. PMCID: PMC2534218 SummaryPage BrowsePDF–1.0MCitation Select item 2534193 2825. Abstracts of Lectures on the Development and Transition of the Testicles, Normal and Abnormal C. B. Lockwood Br Med J. 1887 Feb 26; 1(1365): 444–446. PMCID: PMC2534193 SummaryPage BrowsePDF–1.0MCitation Select item 2534172 2826.