Talk:Genital - Male Development
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Cite this page: Hill, M.A. (2024, May 5) Embryology Genital - Male Development. Retrieved from https://embryology.med.unsw.edu.au/embryology/index.php/Talk:Genital_-_Male_Development |
2011
Normal male sexual differentiation and aetiology of disorders of sex development
Best Pract Res Clin Endocrinol Metab. 2011 Apr;25(2):221-38.
Rey RA, Grinspon RP. Source Centro de Investigaciones Endocrinológicas (CEDIE-CONICET), División de Endocrinología, Hospital de Niños Dr. Ricardo Gutiérrez, C1425EFD Buenos Aires, Argentina. rodolforey@cedie.org.ar
Abstract
Fetal sex development consists of three sequential stages: a) the undifferentiated stage, when identical primitive structures develop in the XY and XX embryos, b) gonadal differentiation into testes or ovaries, and c) the differentiation of internal and external genitalia, which depends on the action of testicular hormones. Disorders of sex development (DSD) may result from defects in any of these stages. Abnormal formation of the anlagen of internal and/or external genitalia in early embryonic development results in Malformative DSD. In patients with a Y chromosome, defects in testis differentiation drive to early-onset fetal hypogonadism affecting whole testicular function, a condition named Dysgenetic DSD. In Non-dysgenetic DSD, the underlying pathogenesis may involve early-onset fetal hypogonadism affecting specifically either Leydig or Sertoli cell function, or male hormone end-organ defects in patients devoid of fetal hypogonadism. Understanding the pathogenesis is useful for an efficient early diagnosis approach, which is necessary for adequate decision making in the management of DSD. Copyright © 2010 Elsevier Ltd. All rights reserved.
PMID 21397195
Second to fourth digit ratio: a predictor of adult penile length
Asian J Androl. 2011 Jul 4. doi: 10.1038/aja.2011.75. [Epub ahead of print]
Choi IH, Kim KH, Jung H, Yoon SJ, Kim SW, Kim TB. Source Department of Urology, Gachon University Gil Hospital, Incheon, Korea.
Abstract
The second to fourth digit ratio (2D:4D) has been proposed as a putative biomarker for prenatal testosterone and covaries with the sensitivity of the androgen receptor (AR). Both prenatal testosterone and the AR play a central role in penile growth. In this study, we investigated the relationship between digit ratio and penile length. Korean men who were hospitalized for urological surgery at a single tertiary academic centre were examined in this study, and 144 men aged 20 years or older who gave informed consent were prospectively enrolled. Right-hand second- and fourth-digit lengths were measured by a single investigator prior to measurement of penile length. Under anaesthesia, flaccid and stretched penile lengths were measured by another investigator who did not measure nor have any the information regarding the digit lengths. Univariate and multivariate analysis using linear regression models showed that only height was a significant predictive factor for flaccid penile length (univariate analysis: r=0.185, P=0.026; multivariate analysis: r=0.172, P=0.038) and that only digit ratio was a significant predictive factor for stretched penile length (univariate analysis:r=-0.216, P=0.009; multivariate analysis: r=-0.201, P=0.024; stretched penile length=-9.201×digit ratio + 20.577). Based on this evidence, we suggest that the digit ratio can predict adult penile size and that the effects of prenatal testosterone may in part explain the differences in adult penile length.Asian Journal of Andrology advance online publication, 4 July 2011; doi:10.1038/aja.2011.75.
PMID 21725330
Penile biometry on prenatal MR imaging
Ultrasound Obstet Gynecol. 2011 Apr 12. doi: 10.1002/uog.9022. [Epub ahead of print]
Nemec SF, Nemec U, Weber M, Brugger PC, Bettelheim D, Rotmensch S, Krestan CR, Rimoin DL, Graham Jr JM, Prayer D.
Department of Radiology, Division of Neuroradiology and Musculoskeletal Radiology, Medical University Vienna, Waehringer Guertel 18-20, A-1090 Vienna, Austria; Medical Genetics Institute, Cedars Sinai Medical Center, 8700 Beverly Boulevard, PACT Suite 400, Los Angeles, California 90048, USA. stefan.nemec@meduniwien.ac.at, stefan.nemec@cshs.org.
Abstract OBJECTIVE: In view of the implementation of magnetic resonance imaging (MRI) as an adjunct to ultrasonography (US) in prenatal diagnosis, this study sought to demonstrate normal penile growth on prenatal MRI.
MATERIALS AND METHODS: This retrospective study included MRI scans of 194 male fetuses (18 to 34 gestational weeks [GW]) with normal anatomy or minor abnormalities. On sagittal T2-weighted MR sequences, penile length was measured from the glans tip to the scrotal edge (outer length), and also, from the glans tip to the symphyseal border (total length). Statistical description, as well as correlation and regression analysis, were used to evaluate penile length in relation to gestation. T-tests were calculated to compare mean outer/total length on MRI with published US data.
RESULTS: Mean length values, including 95% confidence intervals and percentiles, were defined. Penile length as a function of gestational age was expressed by the regression equation: outer mean length= -5.514 + 0.622 *, and total mean length= -8.865 + 1.312 * (*= GW). The correlation coefficients were statistically significant (p < .001). The comparison between outer length on MRI and US data showed no significant differences, whereas total length on MRI and US data demonstrated significant differences (p< .001).
CONCLUSION: Our MRI results provide a reference range of fetal penile length, which, in addition to US, may be helpful in the identification of genital anomalies. Outer penile length on MRI is equivalent to penile length measured on US, whereas total length is significantly different. Copyright © 2011 ISUOG. Published by John Wiley & Sons, Ltd.
Copyright © 2011 ISUOG. Published by John Wiley & Sons, Ltd.
PMID 21484906
2010
Xenografting of human fetal testis tissue: a new approach to study fetal testis development and germ cell differentiation
Hum Reprod. 2010 Oct;25(10):2405-14. Epub 2010 Aug 3.
Mitchell RT, Saunders PT, Childs AJ, Cassidy-Kojima C, Anderson RA, Wallace WH, Kelnar CJ, Sharpe RM.
MRC Human Reproductive Sciences Unit, Centre for Reproductive Biology, The Queen's Medical Research Institute, University of Edinburgh, 47 Little France Crescent, Edinburgh EH16 4TJ, UK. Abstract BACKGROUND: Abnormal fetal testis development can result in disorders of sex development (DSDs) and predispose to later testicular dysgenesis syndrome (TDS) disorders such as testicular germ cell tumours. Studies of human fetal testis development are hampered by the lack of appropriate model, and intervention systems. We hypothesized that human fetal testis xenografts can recapitulate normal development.
METHODS: Human fetal testes (at 9 weeks, n = 4 and 14-18 weeks gestation, n = 6) were xenografted into male nude mice for 6 weeks, with or without hCG treatment of the host, and evaluated for normal cellular development and function using immunohistochemistry, triple immunofluorescence and testosterone assay. The differentiation and proliferation status of germ cells within xenografts was quantified and compared with age-matched controls.
RESULTS: Xenografts showed >75% survival with normal morphology. In the first-trimester xenografts seminiferous cord formation was initiated and in first- and second-trimester grafts normal functional development of Sertoli, Leydig and peritubular myoid cells was demonstrated using cell-specific protein markers. Grafts produced testosterone when hosts were treated with hCG (P = 0.004 versus control). Proliferation of germ cells and differentiation from gonocytes (OCT4(+)) into pre-spermatogonia (VASA(+)) occurred in grafts and quantification showed this progressed comparably with age-matched ungrafted controls.
CONCLUSIONS: Human fetal testis tissue xenografts demonstrate normal structure, function and development after xenografting, including normal germ cell differentiation. This provides an in vivo system to study normal human fetal testis development and its susceptibility to disruption by exogenous factors (e.g. environmental chemicals). This should provide mechanistic insight into the fetal origins of DSDs and TDS disorders.
PMID 20683063
Growth and Development of Male External Genitalia: A Cross-sectional Study of 6200 Males Aged 0 to 19 Years
Arch Pediatr Adolesc Med. 2010 Dec;164(12):1152-7.
Tomova A, Deepinder F, Robeva R, Lalabonova H, Kumanov P, Agarwal A.
HCLD, Reproductive Research Center, Desk A19.1, Glickman Urological and Kidney Institute, and Department of Obstetric and Gynecology, Cleveland Clinic, 9500 Euclid Ave, Cleveland, OH 44195. agarwaa@ccf.org.
OBJECTIVE: To provide estimates of normal variations in penile measurements and testicular volumes, and to establish reference ranges for clinical use.
DESIGN: Cross-sectional, population-based study.
SETTING: Schools, kindergartens, and child care centers in different parts of Bulgaria.
PARTICIPANTS: A population of 6200 clinically healthy white males aged 0 to 19 years.
INTERVENTIONS: The study physician chose schools, kindergartens, and child care centers randomly and examined children at random until he reached the required number. Each of the 20 age groups (age range, 0-19 years) had an equal number of males (ie, 310).
MAIN OUTCOME MEASURES: The mean (SD) values and fifth, 50th, and 95th percentiles of height (Siber Hegner anthropometer), weight (beam balance), testicular volume (Prader orchidometer), penile length (rigid tape), and penile circumference (measuring tape) from birth to 19 years of age.
RESULTS: Testes did not show any increase in size until the onset of puberty at age 11 years, whereas penile growth was gradual after birth. However, both penile and testicular development demonstrated peak growth from 12 to 16 years of age, which coincided with the maximal male pubertal growth spurt. Data indicate an earlier pubertal development for this study population than that for a similar population several decades ago. Significant differences between urban and rural populations regarding penile length were also noticed.
CONCLUSIONS: Our study provides the contemporary reference range values for height, weight, testicular volume, and penile length and circumference of males aged 0 to 19 years. Our data show that, even by the end of 20th century, there is still some acceleration of male pubertal development. For the first time are reported somatic differences in genitalia within a population between urban and rural representatives.
PMID 21135345
Penile embryology and anatomy
ScientificWorldJournal. 2010 Jun 29;10:1174-9.
Yiee JH, Baskin LS.
Department of Urology, University of California San Francisco, USA. yieejh@urology.ucsf.edu Abstract
Knowledge of penile embryology and anatomy is essential to any pediatric urologist in order to fully understand and treat congenital anomalies. Sex differentiation of the external genitalia occurs between the 7th and 17th weeks of gestation. The Y chromosome initiates male differentiation through the SRY gene, which triggers testicular development. Under the influence of androgens produced by the testes, external genitalia then develop into the penis and scrotum. Dorsal nerves supply penile skin sensation and lie within Buck's fascia. These nerves are notably absent at the 12 o'clock position. Perineal nerves supply skin sensation to the ventral shaft skin and frenulum. Cavernosal nerves lie within the corpora cavernosa and are responsible for sexual function. Paired cavernosal, dorsal, and bulbourethral arteries have extensive anastomotic connections. During erection, the cavernosal artery causes engorgement of the cavernosa, while the deep dorsal artery leads to glans enlargement. The majority of venous drainage occurs through a single, deep dorsal vein into which multiple emissary veins from the corpora and circumflex veins from the spongiosum drain. The corpora cavernosa and spongiosum are all made of spongy erectile tissue. Buck's fascia circumferentially envelops all three structures, splitting into two leaves ventrally at the spongiosum. The male urethra is composed of six parts: bladder neck, prostatic, membranous, bulbous, penile, and fossa navicularis. The urethra receives its blood supply from both proximal and distal directions.
PMID 20602076
http://www.thescientificworld.co.uk/TSW/toc/TSWJ_ArticleLanding.asp?ArticleId=3497
2009
Sonic hedgehog, apoptosis, and the penis
J Sex Med. 2009 Mar;6 Suppl 3:334-9.
Podlasek CA.
Department of Urology, Northwestern University Medical School, Chicago, IL 60611, USA. cap325@northwestern.edu Abstract INTRODUCTION: Smooth muscle apoptosis in the penis is common in prostatectomy patients and animal models of erectile dysfunction (ED). A critical regulator of smooth muscle apoptosis in the penis is the secreted protein Sonic hedgehog (SHH). Since SHH protein treatment of the penis prevents cavernous nerve (CN) injury-induced apoptosis, SHH has the potential to treat post-prostatectomy apoptosis. However, little is known about how SHH signaling is regulated in the adult penis.
AIM: The goal of this review is to examine what is known about SHH signaling in the penis, to offer insight as to how SHH inhibition induces apoptosis in penile smooth muscle, and to define the role of the SHH pathway in maintaining CN integrity.
METHODS: Information presented in this review was derived from a literature search using the National Library of Medicine PubMed Services. Search terms included SHH, apoptosis, smooth muscle, penis, ED, pelvic ganglia, corpora cavernosa, CN, regeneration, Schwann cell, neural activity, and transport.
RESULTS: In this review, we have discussed the role of the CN in regulation of SHH abundance and apoptosis induction in the penis, and have examined the function and localization of SHH signaling in the CN.
CONCLUSION: There is substantial potential to develop SHH for delivery to the penis of prostatectomy patients at the time of surgery in order to prevent apoptosis induction and long-term ED development. Studies are in progress that will identify if SHH may be used as a regenerative therapy to speed CN regeneration.
PMID 19267857
The adrenal cortex and sexual differentiation during early human development
Rev Endocr Metab Disord. 2009 Mar;10(1):43-9.
Asby DJ, Arlt W, Hanley NA. Source Human Genetics Division, University of Southampton, Southampton General Hospital, Tremona Road, Southampton, UK. Abstract Human sexual differentiation is a critical process whereby a strict dimorphism is established that enables future reproductive success as phenotypic males and females. Significant components of this differentiation pathway unfold during the first three months of gestation when they are sensitive to disruption by abnormal hormonal influences. Excessive exposure of female development to androgens in conditions such as congenital adrenal hyperplasia causes virilization. However, recently we have suggested that female development normally takes place in the presence of low, yet significant, levels of androgen, implying a need for strict regulation to avoid virilization and the potential for a biological role of androgens in females that has not been fully elucidated. Here, we review androgen-dependent male differentiation of the external genitalia in humans, and link this to current understanding of female development and steroidogenesis in the developing adrenal cortex.
PMID 18670886
2004
Anatomy of the human penis: the relationship of the architecture between skeletal and smooth muscles
J Androl. 2004 May-Jun;25(3):426-31.
Hsu GL, Hsieh CH, Wen HS, Hsu WL, Wu CH, Fong TH, Chen SC, Tseng GF. Source Microsurgical Potency Reconstruction Center, Taiwan Adventist Hospital, Taipei Medical University Hospital, Taipei, Taiwan, Republic of China. glhsu@tahsda.org.tw Abstract To investigate the anatomy of the ischiocavernosus muscle, bulbospongiosus muscle, and tunica albuginea and to determine their relationships to smooth muscle, which is a key element of penile sinusoids, we performed cadaveric dissection and histologic examinations of 35 adult human male cadavers. The tunica of the corpora cavernosa is a bilayered structure that can be divided into an inner circular layer and an outer longitudinal layer. The outer longitudinal layer is an incomplete coat that is absent between the 5-o'clock and 7-o'clock positions where 2 triangular ligamentous structures form. These structures, termed the ventral thickening, are a continuation of the anterior fibers of the left and right bulbospongiosus muscles. On the dorsal aspect, between the 1-o'clock and 11-o'clock positions, is a region called the dorsal thickening, a radiating aspect of the bilateral ischiocavernosus muscles. In the corpora cavernosa, skeletal muscle contains and supports smooth muscle, which is an essential element in the sinusoids. This relationship plays an important part in the blood vessels' ability to supply the blood to meet the requirements for erection, whereas in the corpus spongiosum, skeletal muscle partially entraps the smooth muscle to allow ejaculation when erect. In the glans penis, however, the distal ligament, a continuation of the outer longitudinal layer of the tunica, is arranged centrally and acts as a trunk of the glans penis. Without this strong ligament, the glans would be too weak to bear the buckling pressure generated during coitus. A significant difference exists in the thickness of the dorsal thickening, the ventral thickening, and the distal ligament between the potent and impotent groups (P < or =.01). Together, the anatomic relationships between skeletal muscle and smooth muscle within the human penis explain many physiologic phenomena, such as erection, ejaculation, the intracavernous pressure surge during ejaculation, and the pull-back force against the glans penis during anal constriction. This improvement in the modeling of the anatomic-physiologic relationship between these structures has clinical implications for penile surgeries.
PMID 15064322
