Prenatal ultrasound diagnosis of chordee without hypospadias

Chordee without hypospadias (CWH) is an extremely rare condition. Here, we describe a case of CWH diagnosed accurately on prenatal ultrasound at 25 weeks' gestation. Physical examination of the newborn confirmed the sonographic findings. To the best of our knowledge, prenatal ultrasound diagnosis of CWH has not been reported in the literature. We emphasize the importance of observing fetal micturition to rule out the possibility of CWH before the diagnosis of hypospadias is made on prenatal ultrasound.

Androgen and estrogen receptor expression in the developing human penis and clitoris

To better understand how the human fetal penis and clitoris grows and remodels, we undertook an investigation to define active areas of cellular proliferation and programmed cell death spatially and temporally during development of human fetal external genitalia from the indifferent stage (8 weeks) to 18 weeks of gestation. Fifty normal human fetal penile and clitoral specimens were examined using macroscopic imaging, scanning electron microscopy and immunohistochemical localization for the cellular proliferation and apoptotic markers, Ki67 and Caspase-3. A number of hot spots of cellular proliferation characterized by Ki67 localization are present in the penis and clitoris especially early in development, most notably in the corporal body, glans, remodeling glanular urethra, the urethral plate, the roof of the urethral groove and the fully formed penile urethra. The 12-fold increase in penile length over 10 weeks of growth from 8 to 18 weeks of gestation based on Ki67 labelling appears to be driven by cellular proliferation in the corporal body and glans. Throughout all ages in both the developing penis and clitoris Ki67 labeling was consistently elevated in the ventral epidermis and ventral mesenchyme relative to the dorsal counterparts. This finding is consistent with the intense morphogenetic activity/remodeling in the ventral half of the genital tubercle in both sexes involving formation of the urethral/vestibular plates, canalization of the urethral/vestibular plates and fusion of the urethral folds to form the penile urethra. Areas of reduced or absent Ki67 staining include the urethral fold epithelium that fuses to form the penile tubular urethra. In contrast, the urethral fold mesenchyme is positive for Ki67. Apoptosis was rarely noted in the developing penis and clitoris; the only area of minimal Caspase-3 localization was in the epithelium of the ventral epithelial glanular channel remodeling.

Differential cell proliferation and cell death during the urethral groove formation in guinea pig model

BACKGROUND

Urethral groove (UG) formation is an important step in penile formation. Because commonly used animal models do not have UG, the mechanisms of UG formation have never been discovered. We aim to discover the cellular mechanism of the UG formation using guinea pig model.

METHODS

Histology was used to study the ontogeny of UG. BrdU immunofluorescence was used to label proliferating cells, cell death was determined using LysoTracker Red and TUNEL staining, and stereology was used for quantification. To reveal Shh mRNA expression patterns, in situ hybridization was performed in guinea pig genital tubercles (GTs) and ShhGFPcre-LacZ-reporter mice were used for comparison.

RESULTS

Cell proliferation in the outer layers and programmed cell death in the inner layers of urethral epithelium played key roles during urethral canal movement from dorsal to ventral aspect and final opening to form UG. Shh mRNA expression domain shifted out to the ventral surface of GT from proximal throughout to distal in guinea pigs, but was excluded from the ventral surface epithelium in midshaft and distal of mouse GT.

CONCLUSION

Differential cell proliferation and cell death in developing urethral epithelium lead to UG formation and Shh expression in ventral surface epithelium of GT may play an important role.

Resurrecting embryos of the tuatara, Sphenodon punctatus, to resolve vertebrate phallus evolution

The breadth of anatomical and functional diversity among amniote external genitalia has led to uncertainty about the evolutionary origins of the phallus. In several lineages, including the tuatara, Sphenodon punctatus, adults lack an intromittent phallus, raising the possibility that the amniote ancestor lacked external genitalia and reproduced using cloacal apposition. Accordingly, a phallus may have evolved multiple times in amniotes. However, similarities in development across amniote external genitalia suggest that the phallus may have a single evolutionary origin. To resolve the evolutionary history of amniote genitalia, we performed three-dimensional reconstruction of Victorian era tuatara embryos to look for embryological evidence of external genital initiation. Despite the absence of an intromittent phallus in adult tuataras, our observations show that tuatara embryos develop genital anlagen. This illustrates that there is a conserved developmental stage of external genital development among all amniotes and suggests a single evolutionary origin of amniote external genitalia.

[Genes associated with hypospadias: an update]

Hypospadias is one of the most common congenital malformations, and its main clinical manifestation is the abnormal opening of the urethra. Etiologically, it can be attributed to many factors, mainly including genetic, hormonal, and environmental factors. Recently studies about its genetic etiologies have found a variety of hypospadias-associated genes from the aspects of epidemiology and polymorphism, mainly those involving the formation of the penis, the development of the testis, the anabolism of androgens, and so on. This review focuses on the progress in the studies on the genetic etiology of hypospadias.

Modifications of erectile tissue components in the penis during the fetal period

BACKGROUND

The penile erectile tissue has a complex microscopic anatomy with important functions in the mechanism of penile erection. The knowledge of such structures is necessary for understanding the normal physiology of the adult penis. Therefore, it is important to know the changes of these penile structures during fetal development. This study aims to analyze the development of the main components of the erectile tissue, such as collagen, smooth muscle fibers and elastic system fibers, in human fetuses.

METHODOLOGY/PRINCIPAL FINDINGS

We studied the penises of 56 human fetuses aged 13 to 36 weeks post-conception (WPC). We used histochemical and immunohistochemical staining, as well as morphometric techniques to analyze the collagen, smooth muscle fibers and elastic system fibers in the corpus cavernosum and in the corpus spongiosum. These elements were identified and quantified as percentage by using the Image J software (NIH, Bethesda, USA). From 13 to 36 WPC, in the corpus cavernosum, the amount of collagen, smooth muscle fibers and elastic system fibers varied from 19.88% to 36.60%, from 4.39% to 29.76% and from 1.91% to 8.92%, respectively. In the corpus spongiosum, the amount of collagen, smooth muscle fibers and elastic system fibers varied from 34.65% to 45.89%, from 0.60% to 11.90% and from 3.22% to 11.93%, respectively.

CONCLUSIONS

We found strong correlation between the elements analyzed with fetal age, both in corpus cavernosum and corpus spongiosum. The growth rate of these elements was more intense during the second trimester (13 to 24 WPC) of gestation, both in corpus cavernosum and in corpus spongiosum. There is greater proportional amount of collagen in the corpus spongiosum than in corpus cavernosum during all fetal period. In the corpus spongiosum, there is about four times more collagen than smooth muscle fibers and elastic system fibers, during all fetal period studied.

Penile biometry on prenatal magnetic resonance imaging

OBJECTIVE

In view of the implementation of magnetic resonance imaging (MRI) as an adjunct to ultrasonography in prenatal diagnosis, this study sought to demonstrate normal penile growth on prenatal MRI.

METHODS

This was a retrospective study of MRI of 194 male fetuses (18-34 weeks' gestation) with normal anatomy or minor abnormalities. On sagittal T2-weighted MRI sequences, we measured penile length from the glans tip to the scrotal edge (outer length) and from the glans tip to the symphyseal border (total length). Descriptive statistics, 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 ultrasound data.

RESULTS

Mean length values, including 95% CIs and percentiles, were defined. Penile length as a function of gestational age was expressed by the following regression equations: outer mean length = - 5.514 + 0.622 × gestational age in weeks; total mean length = - 8.865 + 1.312× gestational age in weeks. The correlation coefficients, r = 0.532 and r = 0.751, respectively, were statistically significant (P < 0.001). Comparison of outer penile length on MRI with published ultrasound penile length data showed no significant differences, while total penile length on MRI was significantly greater than ultrasound penile length (P < 0.001).

CONCLUSION

Our MRI results provide a reference range of fetal penile length, which, in addition to ultrasonography, may be helpful in the identification of genital anomalies. Outer penile length on MRI is equivalent to penile length measured on ultrasound, whereas total length is significantly greater.

Estrogen receptor alpha mediates estrogen-inducible abnormalities in the developing penis

Previously, we reported an association between estrogen receptor-alpha (ERalpha) upregulation and detrimental effects of neonatal diethylstilbestrol (DES) exposure in the rat penis. The objective of this study was to employ the ERalpha knockout (ERalphaKO) mouse model to test the hypothesis that ERalpha mediates DES effects in the developing penis. ERalphaKO and wild-type C57BL/6 mice received oil or DES at a dose of 0.2 microg/pup per day (0.1 mg/kg) on alternate days from postnatal days 2 to 12. Fertility was tested at 80-240 days of age and tissues were examined at 96-255 days of age. DES caused malformation of the os penis, significant reductions in penile length, diameter, and weight, accumulation of fat cells in the corpora cavernosa penis, and significant reductions in weight of the bulbospongiosus and levator ani muscles in wild-type mice. Conversely, ERalphaKO mice treated with DES developed none of the above abnormalities. While nine out of ten male mice sired pups in the wild-type/control group, none did in the wild-type/DES group. ERalphaKO mice, despite normal penile development, are inherently infertile. Both plasma and intratesticular testosterone levels were unaltered in the DES-treated wild-type or DES-treated ERalphaKO mice when compared with controls, although testosterone concentration was much higher in the ERalphaKO mice. Hence, the resistance of ERalphaKO mice to developing penile abnormalities provides unequivocal evidence of an obligatory role for ERalpha in mediating the harmful effects of neonatal DES exposure in the developing penis.

Essential role for Co-chaperone Fkbp52 but not Fkbp51 in androgen receptor-mediated signaling and physiology

Fkbp52 and Fkbp51 are tetratricopeptide repeat proteins found in steroid receptor complexes, and Fkbp51 is an androgen receptor (AR) target gene. Although in vitro studies suggest that Fkbp52 and Fkbp51 regulate hormone binding and/or subcellular trafficking of receptors, the roles of Fkbp52 and Fkbp51 in vivo have not been extensively investigated. Here, we evaluate their physiological roles in Fkbp52-deficient and Fkbp51-deficient mice. Fkbp52-deficient males developed defects in select reproductive organs (e.g. penile hypospadias and prostate dysgenesis but normal testis), pointing to a role for Fkbp52 in AR-mediated signaling and function. Surprisingly, ablation of Fkbp52 did not affect AR hormone binding or nuclear translocation in vivo and in vitro. Molecular studies in mouse embryonic fibroblast cells uncovered that Fkbp52 is critical to AR transcriptional activity. Interestingly, Fkbp51 expression was down-regulated in Fkbp52-deficient males but only in affected tissues, providing further evidence of tissue-specific loss of AR activity and suggesting that Fkbp51 is an AR target gene essential to penile and prostate development. However, Fkbp51-deficient mice were normal, showing no defects in AR-mediated reproductive function. Our work demonstrates that Fkbp52 but not Fkbp51 is essential to AR-mediated signaling and provides evidence for an unprecedented Fkbp52 function, direct control of steroid receptor transcriptional activity.

Molecular genetic cascades for external genitalia formation: an emerging organogenesis program

External genitalia are anatomical structures located at the posterior embryonic region as part of several urogenital/reproductive organs. The embryonic anlage of the external genitalia, the genital tubercle (GT) develops as a bud-shaped structure with an initial urethral plate and later urethra. Embryonic external genitalia are considered to be one of the appendages. Recent experiments suggest that essential regulatory genes possess similar functions for the outgrowth regulation of the GT and limb appendages. The transient embryonic epithelia located in the distal GT are called the distal urethral epithelium (DUE) regulating, at least in part, the (distal) GT development. This review covers the available data about early patterning of GT and discusses the molecular developmental similarities and points of divergence between the different appendages. Development of the male and female external genitalia is also reviewed.

A case of congenital megalourethra

Congenital megalourethra is a rare anomaly of the penile urethra caused by a mesenchymal defect. We describe a baby boy with scaphoid type megalourethra and review the embryology and management of this condition.

Prenatal Sonographic Features of Hypospadia: Two- and Three-Dimensional Findings

OBJECTIVE

To present our experience of applying three-dimensional ultrasonography in prenatal diagnosis of hypospadia.

CASE REPORT

A 28-year-old woman, gravida 1, para 0, visited our hospital at 17 weeks' gestation. No gross anomaly was found on the scan at 21 weeks' gestation. Fetal growth was appropriate for gestational age on two-dimensional (2D) ultrasonography at 27 weeks' gestation, but an abnormally curved and shortened fetal penis was found incidentally. Three-dimensional (3D) imaging in surface-rendered mode was used to reconstruct the fetal penis. Multiplanar and surface-rendered images were obtained in the midsagittal, axial, and coronal planes to precisely delineate the ventral curvature of the penis. At 39 weeks' gestation, a term newborn was delivered by vacuum extraction. On examination, the fetus was confirmed to have hypospadia. Karyotyping revealed 46,XY.

CONCLUSION

2D ultrasonography could only give indirect clues of hypospadia that was later more precisely delineated by 3D ultrasonography in surface-rendered mode.

COMPOSITIONAL CHANGES OF COLLAGEN AND GLYCOSAMINOGLYCANS IN THE TUNICA ALBUGINEA AND CORPUS CAVERNOSUM FROM THE HUMAN PENIS DURING THE FETAL AND POSTNATAL PERIODS

PURPOSE

We investigated the composition of collagen and glycosaminoglycans (GAGs) in the corpus cavernosum (CC) and tunica albuginea (TA) of normal human penises.

MATERIALS AND METHODS

Penises were obtained from a 6-month-old child (group 1), a 2-year-old child (group 2), 18 to 34-year-old adults (group 3), 37 to 53-year-old adults (group 4) and 22 fetuses at 17.2 to 33.3 menstrual weeks (group 5). Total GAG and collagen concentrations were expressed per mg dry tissue and proportions of GAG species were determined by agarose electrophoresis and ion exchange chromatography.

RESULTS

The GAG concentration in group 1 CC and TA was 1.32 and 0.52 microg/mg, respectively, and thereafter it increased noticeably. TA collagen concentration followed a similar pattern. TA had more collagen than CC in groups 3 (mean +/- SD 93.41 +/- 6.17 vs 53.77 +/- 11.18 microg/mg, p <0.001) and 4 (89.94 +/- 5.53 vs 55.39 +/- 5.89 microg/mg, p <0.01). In these groups TA and CC differed markedly in the proportion of hyaluronan, heparan sulfate and dermatan sulfate. In TA group 4 had slightly less hyaluronan and more chondroitin sulfate than group 3 but in CC the GAG proportions were similar. Collagen content in the whole fetal penis correlated with gestational age (r = 0.78, p <0.001).

CONCLUSIONS

Collagen and the GAG concentration in the human penis undergo extensive modifications during development and shortly after birth but from ages 2 to approximately 46 years changes are limited to the proportion of GAG species in TA from older individuals. Reflecting diverse biomechanical roles, the extracellular matrix of CC and TA are markedly different.

Identification, characterization and biological activity of oxytocin receptor in the developing human penis

Although abnormalities of the male external genitalia (MEG) are a relatively common problem, little is known concerning the molecular mechanisms that finely regulate penile development. We report here the expression of the oxytocin receptor (OTR) gene by real-time RT-PCR in human fetal tissues (11th-12th week of gestation), including the MEG. The developing penis expressed a very high level of OTR mRNA, only a half log(10) unit lower than fetal central nervous system, used as a positive control. The OTR protein is also highly expressed (western, immunohistochemistry and binding studies) and immunolocalized both in the mesenchymal body and in the surrounding blood capillaries, which will later constitute penile trabeculae and sinusoids. Binding studies using [125I]oxytocin antagonist ([125I]OTA) in cultured human fetal penile smooth muscle cells (hfPSMC) revealed the presence of specific OTR with a high capacity and affinity for oxytocin (OT) and for OTA. Increasing concentrations of OT dose-dependently induced intracellular Ca2+ mobilization. Furthermore, OTR mediated an increase in the proliferation and the migration of hfPSMC. In conclusion, we demonstrate that in the developing human MEG, OTR is highly expressed and might be involved in coordinating timely and appropriate proliferation and migration of the penile cells. Thus, OTR might represent an additional target for investigating human fetal MEG organogenesis.

Sexual differentiation of the copulatory neuromuscular system in green anoles (Anolis carolinensis): Normal ontogeny and manipulation of steroid hormones

The copulatory neuromuscular system of green anoles is sexually dimorphic and differentiates during embryonic development, although details of the process were unknown. In Experiment 1, we determined the time course of normal ontogeny. Both male and female embryos possessed bilateral copulatory organs (hemipenes) and associated muscles until incubation day 13; the structures completely regressed in female embryos by incubation day 19 (total incubation 34 days). In Experiment 2, we treated eggs with testosterone, dihydrotestosterone, estradiol, or vehicle on both incubation days 10 and 13 to determine whether these steroid hormones mediate sexual differentiation. These time points fall between gonadal differentiation, which was determined in Experiment 1 to complete before day 10, and regression of the peripheral copulatory system in females. Tissue was collected on the day of hatching. Gonads were classified as testes or ovaries; presence versus absence of hemipenes and muscles, and the number and size of copulatory motoneurons were determined. Copulatory system morphology of vehicle-treated animals matched their gonadal sex. Hemipenes and muscles were absent in estradiol-treated animals, and androgens rescued the hemipenes and muscles in most females. Both testosterone and dihydrotestosterone treatment also caused hypertrophy of the hemipenes, which were everted in animals treated with these steroids. Copulatory motoneurons, assessed on the day of hatching in both experiments, were not dimorphic in size or number. Steroid treatment significantly increased motoneuron size and number overall, but no significant differences were detected in pairwise comparisons. These data demonstrate that differentiation of peripheral copulatory neuromuscular structures occurs during embryonic development and is influenced by gonadal steroids (regression by estradiol and enhancement by androgens), but associated motoneurons do not differentiate until later in life.

Immunohistochemical localization of androgen receptors in the urogenital tracts of human embryos

The aim of this study was to investigate androgen receptor (AR) expression in the developing human urogenital tract. The distribution of AR was examined in paraffin-embedded tissue sections of the lower urogenital tract using 55 human embryos of 8-12 weeks of gestation. Immunohistochemistry was performed for AR detection and gender was determined by polymerized chain reaction. There were no differences in the distribution of AR in male and female embryos at any stage of gestation. AR was present only in the mesenchymal tissues of the urogenital sinus at 8 weeks whilst the epithelium was negative, but after 9 weeks the epithelium also showed progressively more positive staining. In the phallus, AR staining was prominent. There was far less staining in the epithelium of the urethral groove from 8 to 10 weeks, whilst the mesenchyme of the urethral folds showed positive staining. At 11 and 12 weeks, both the urethral groove and folds showed uniform staining. The genital tubercle, genital swelling and bulbourethral gland precusors were also positively stained, although paramesonephric ducts were negative. Staining was observed in the mesonephric duct from 9 weeks. There was an absence of staining in the rectum at all stages of gestation. The expression of AR in an epithelium may be dependent upon the mesenchyme. Mesenchymal-epithelial interactions played an important role in development, as has been described in experimental animals. AR expression could play a part in the growth of the genital organs.

Penile development is initiated in the tammar wallaby pouch young during the period when 5alpha-androstane-3alpha,17beta-diol is secreted by the testes

Virilization of the urogenital tract is under the control of testicular androgens in all mammals. In tammar young, prostate differentiation begins between d 20 and d 40 under the control of the testicular androgen 5alpha-androstane-3alpha,17beta-diol (5alpha-adiol), but uncertainties exist about the control of penile development. We performed longitudinal studies up to d 150 of pouch life to define normal penile development and the effects of androgen administration and castration. In control animals the male phallus was longer than the female phallus by d 48. Closure of the urethra in males begins around d 60 and continues to at least d 150. Administration of supraphysiological doses of testosterone to females caused penile development equivalent to that of the male and also induced partial closure of the urethral groove by d 150. Castration of male pouch young at d 25 prevented penile development, whereas the penis in males castrated at d 40, 80, or 120 had partial closure of the urethral groove. Administration of 5alpha-adiol to females from d 20-40 also caused partial closure of the urethral groove and some growth of the phallus at d 150, whereas 5alpha-adiol treatment from d 40-80 or 80-120 caused some penile growth but had little effect on urethral development. These findings, together with the fact that we found no sex differences in plasma levels of testosterone, dihydrotestosterone, 5alpha-adiol, dehydroepiandrosterone, or androstenedione from d 51-227, clearly indicate that the action of 5alpha-adiol between d 20 and 40 imprints later differentiation of the male penis.

Morphological features of external genitalia in hypospadiac rat model: 3-dimensional analysis

PURPOSE

We examined 3-dimensionally the process of external genitalia formation in the experimental hypospadiac rat model.

MATERIALS AND METHODS

We administered 7.5 mg flutamide daily, a blocker of androgen receptor, into the abdomen of naturally pregnant female Sprague-Dawley rats from gestational days 14 to 20 to produce a hypospadiac rat model. The control group consisted of male offspring not exposed to flutamide. The fetal phallus was obtained at gestational days 17.5, 19.5 and 21.5. We observed them by scanning electron microscopy.

RESULTS

In the 17.5-day-old embryo the projection on the ventral side of the phallus was observed from the base of the phallus to the coronary sulcus in the control rat. This finding demonstrated that the urethra develops from the base of the phallus to the coronary sulcus. On the other hand, this projection was not observed in the hypospadiac rat and the urethra was not seen on the ventral side of the phallus. In the 19.5-day-old embryo the ventral preputial closure appeared in the proximal phallus of the control rat but not of the hypospadiac rat. In the control rat the scrotum was discerned in the perineum and divided by a median fold (the raphe). The raphe reached the base of the phallus, where it was concurrent with the preputial fold that covers the urethra. On the other hand, the hypospadiac rat did not have a raphe and the hollow at the base of the phallus appeared to give rise to the future orifice of the urethra. In the 21.5-day-old embryo the control rat prepuce completely surrounded the distal phallus, whereas that of the hypospadiac rat was dorsally hooded with a ventral cleft and the external appearance resembled the morphology of human penoscrotal hypospadias.

CONCLUSIONS

This hypospadiac rat model is considered valuable for further studying penile growth and differentiation, and the molecular mechanisms in external genitalia formation in hypospadias.

Identification of communicating branches among the dorsal, perineal and cavernous nerves of the penis

PURPOSE

The mechanism of human erection requires the coordination of an intact neuronal system that includes the cavernous, perineal, and dorsal nerves of the penis. We defined the communication of these 3 nerves that travel under the pubic arch using specific neuronal immunohistochemical staining and 3-dimensional reconstruction imaging technique.

MATERIALS AND METHODS

A total of 18 normal human fetal penile specimens at 17.5 to 32 weeks of gestation were studied by immunohistochemical techniques. Serial sections were stained with antibodies raised against the neuronal markers S-100, and neuronal nitric oxide synthase (nNOS), vesicular acetylcholine transporter (VAChT), calcitonin gene-related peptide and substance P.

RESULTS

The continuation of the dorsal neurovascular bundle of the prostate was documented under the pubic arch. Two distinct nerve bundles were identified superior to the urethra and medial to the origin of the crural bodies. Nerve bundles were observed to join the corporeal bodies at the penile hilum. Proximal to the penile hilum the dorsal nerves stained only for S-100 and VAChT. From the junction of the crural bodies at the hilum to the glans penis dorsal nerve fibers stained positive for S-100, VAChT and nNOS. Calcitonin gene-related peptide and substance P demonstrated positive staining at the distal nerves, particularly at the glans. In contrast, the whole course of the cavernous nerve stained for S-100 and nNOS. Under the pubic arch at the penile hilum the cavernous nerves were found to convey nNOS positive branches to the dorsal nerve to transform its immunoreactivity to nNOS positive. Proximal nNOS negative perineal nerves were shown to stain positive for nNOS distal on the penis. Interaction between nNOS positive dorsal nerve branches and perineal nerves was at the cavernous-spongiosal junction, where the bulbospongiosus muscle terminates.

CONCLUSIONS

At penile hilum, where the corporeal bodies start to separate, the cavernous nerve sends nNOS positive fibers to join the dorsal nerve of the penis, thereby, changing the functional characteristics of the distal penile dorsal nerve. Similarly the nNOS negative, ventrally located perineal nerve originating from the pudendal nerve becomes nNOS reactive at the cavernous-spongiosal junction. These 2 examples of redundant neuronal wiring in the penis may impact erectile function, especially during reconstructive surgery.

Loss of Bmp7 and Fgf8 signaling in Hoxa13-mutant mice causes hypospadia

In humans and mice, mutations in Hoxa13 cause malformation of limb and genitourinary (GU) regions. In males, one of the most common GU malformations associated with loss of Hoxa13 function is hypospadia, a condition defined by the poor growth and closure of the urethra and glans penis. By examining early signaling in the developing mouse genital tubercle, we show that Hoxa13 is essential for normal expression of Fgf8 and Bmp7 in the urethral plate epithelium. In Hoxa13(GFP)-mutant mice, hypospadias occur as a result of the combined loss of Fgf8 and Bmp7 expression in the urethral plate epithelium, as well as the ectopic expression of noggin (Nog) in the flanking mesenchyme. In vitro supplementation with Fgf8 restored proliferation in homozygous mutants to wild-type levels, suggesting that Fgf8 is sufficient to direct early proliferation of the developing genital tubercle. However, the closure defects of the distal urethra and glans can be attributed to a loss of apoptosis in the urethra, which is consistent with reduced Bmp7 expression in this region. Mice mutant for Hoxa13 also exhibit changes in androgen receptor expression, providing a developmental link between Hoxa13-associated hypospadias and those produced by antagonists to androgen signaling. Finally, a novel role for Hoxa13 in the vascularization of the glans penis is also identified.

Expression of functional estrogen receptors in human fetal male external genitalia

It is generally assumed that male genital development is determined by androgens on a default program leading to female genitalia. Female genitalia virilization is due to high levels of androgens, whereas feminization is linked to reduction or lack of fetal androgen. Excess androgen determines sex reversion in female, whereas excess estrogen does not cause male feminization. In the present study, we investigate the presence of androgen receptors (AR) and estrogen receptors (ER) in human fetal penile tissue and in a cellular model of human fetal penile smooth muscle cells (hfPSMC). By immunohistochemistry, we showed the presence of ER and AR in the developing penile tissue of male fetuses. Besides the presence of AR, hfPSMC showed ERalpha/beta as demonstrated by RT-PCR, Western blot, and binding techniques. These receptors are functionally active because cell stimulation with 17beta-estradiol increased progesterone receptor B expression and inhibited hfPSMC growth, both effects being reversed by tamoxifen. Conversely, cell proliferation was stimulated by R1881 and testosterone, an effect enhanced by letrozole. These findings are the first demonstration of the presence of functional ER in differentiating male external genitalia and indicate a possible novel inhibitory role of estrogens in the regulation of the development of these sex structures.

The neuroanatomy of the human scrotum: surgical ramifications

OBJECTIVE

To define the scrotal nerve origin and distribution with respect to surrounding structures in male human fetuses, by using neuronal-specific markers and three-dimensional (3D) imaging techniques, as the developmental neuroanatomy of the human scrotum has not been studied in detail and an explicit description of nerve derivation and distribution in the human scrotum is germane to genital reconstructive surgery.

MATERIALS AND METHODS

Sixteen normal human fetal penile specimens at 17.5-38 weeks of gestation were studied. Specimens were fixed in formalin, embedded in paraffin wax, serially sectioned at 6 micro m and stained with the neuronal marker S-100. All of the specimens contained the whole penis and scrotum from glans to anal verge. The gestational age of the fetuses was determined by fetal heel-to-toe length. 3D-computer reconstruction of serial sections allowed a detailed analysis of the neuroanatomy of the fetal penis and scrotum.

RESULTS

The nerves innervating the ventral side of the proximal penis and scrotum originated mainly from the perineal nerves arising from pudendal nerves. The nerves travelling along the ventral side of penis coalesced at the penoscrotal area to be directed into the interscrotal septum. At the penoscrotal junction, nerves on both sides of the ventral penis shifted to the interscrotal septum in a triangular fashion. The interscrotal septum was densely occupied by nerve fibres. Nerves were distributed horizontally to both hemiscrotal walls through this interscrotal septum. Both hemiscrota seem primarily to be innervated separately.

CONCLUSION

The interscrotal septum has a dense innervation. Both hemiscrota were innervated mainly by horizontally distributed nerve fibres arising from the interscrotal septum. Any procedure violating the penoscrotal and interscrotal septal area may jeopardize scrotal innervation.

Prenatal diagnosis of sex differentiation disorders: the role of fetal ultrasound

We describe our experience with prenatal diagnosis of sex differentiation disorders, with focus on the role of ultrasound scans for coherent assessment of prenatal diagnosis. Over a 5-yr period all cases suspected of sexual ambiguity based on abnormal ultrasonographic scans (US) or US/genotype US discrepancy were evaluated prenatally by three modalities: 1) repeated fetal US; 2) genetic studies, primarily karyotype and fluorescence in situ hybridization analysis of sex-determining region on the Y gene (SRY); and 3) hormonal assays of amniotic fluid. Of approximately 10,000 gestations, 16 fetuses underwent prenatal evaluation. Twelve were referred because of an abnormal US and 4 because of genotype-phenotype discrepancy. Five fetuses were diagnosed with female pseudohermaphroditism (21-hydroxylase deficiency in 3 and urorectal septum malformation sequence in 2). Four fetuses were diagnosed with male pseudohermaphroditism (1 with steroid sulfatase deficiency, 1 with presumed camptomelic dysplasia, and 2 undetermined). Five cases had chromosomal abnormalities, and 2 had 46,XX+SRY sex reversal. In all genetic females the uterus was observed on US. In 11 cases initial US scan was performed at 13-15 wk; in 7 of 11, although the initial scan was normal, a repeated scan later in gestation revealed an abnormality. Repeated US scans performed at 13-15 and 22-24 wk gestation are a helpful tool in prenatal diagnosis of sex differentiation disorders. Our data suggest that both size and structure anomalies of the reproductive structures may evolve throughout pregnancy, and that they represent a developmental biological process rather than a single nonprogressive pathological event. US scan after approximately 19 wk enables detection of the uterus and provides pivotal information in cases of ambiguity. If the uterus appears normal, the most likely diagnosis is a virilized karyotypic female. Prenatal diagnosis allows for early parental counseling and anticipation of medical management postnatally.

Clinical and embryologic aspects of penile duplication and associated anomalies

OBJECTIVES

To report 2 cases of penile duplication and review the literature in an attempt to categorize the associated anomalies in relation to the degree of penile duplication. Embryologic considerations of this rare anomaly are also reviewed.

METHODS

We report 2 distinct cases of diphallia. In the first case, true complete penile duplication was associated with multiple malformations, including a cloacal anomaly, colon and bladder duplication, a horseshoe kidney, a bifid scrotum with undescended testes, a hypoplastic right leg, and a ventricular septum defect. The second patient presented with true, complete diphallia and bladder and urethral duplication but an absence of other anomalies. The patients were individually treated according to the concomitant malformations. A review of published reports allowed a classification of associated anomalies in 77 cases of diphallia, according to the degree of penile duplication.

RESULTS

The first patient underwent a series of staged surgical repairs, including correction of the congenital heart anomaly, separation of the urogenital and gastrointestinal tract and resection of the duplicate terminal colon, excision of the smaller bladder and underdeveloped duplicate penis, bilateral orchiopexy, and hypospadias correction. The second patient underwent bladder fusion and excision of a urethrorectal fistula. Penile reconstruction was left for a later stage. An analysis of the cases available in published studies suggests that diphallia is often associated with a wide spectrum of anomalies that vary from severe malformations to less significant variations of human anatomy.

CONCLUSIONS

Penile duplication is a rare anomaly. Thorough investigations are mandatory in all cases to reveal underlying congenital malformations that are potentially life threatening and require immediate surgical correction. Treatment should always be individualized according to the degree of penile duplication and the extent of the concomitant anomalies.

Complete bladder exstrophy with a normal phallus: A variant of superior vesical fissure

Variations in the anatomic defects of the bladder exstrophy are well recognized, but their incidence is extremely low. Here the authors describe a rare case of superior vesical fissure in which a relatively large defect caused the whole bladder to prolapse outside. A review of literature found only 2 other cases that resembled our case. This particular variation of exstrophy is not only important owing to its extreme rarity but also raises a question for an embryologic explanation.

Management of chordee in children and young adults

Penile curvature is a spectrum of disease affecting boys with and without hypospadias. The etiology of chordee includes skin tethering, fibrotic bucks or dartos fascia, corporeal body disproportion and rarely a fibrotic urethra. Several surgical techniques (plication, excision, and graft insertion) are currently employed to repair penile curvature. Recent neuroanatomical studies of the developing fetal penis have shown that the dorsal nerve branches from the 11 and 1 o'clock positions to the 5 and 7 o'clock positions, being absent in the midline. Since the neuroanatomy is similar in both the hypospadiac and normal penis, we now recommend performing penile straightening in both hypospadiac and non hypospadiac patients with significant curvature by the placement of plication sutures at the 12 o'clock position. Placement of dorsal midline plication sutures corrects curvature without risk to the underlying nerve structures.

Ontogenetic reaction norm for binary traits: the timing of phallus development in the snail Bulinus truncatus

The ontogenetic trajectory of plastic binary traits may provide valuable insights into their evolutionary rate of change. In this paper, the timing of the plastic response of a temperature-dependent sexual polymorphism, aphally, is investigated in the freshwater snail Bulinus truncatus. Aphally is defined as the loss of the male copulatory organ in otherwise hermaphroditic animals. Individuals from two inbred lines were switched at various times during their early development between 25 and 30 degrees C, and their phally status ascertained, in order to evaluate the parameters characterising the ontogenetic reaction norm of aphally to temperature. A series of nested models including parameters for the onset, offset, and the intensity of the response to temperature were fitted to the data, allowing for a wide range of reaction norms. One genotype did not show any variation in aphally ratio with switching temperature, while a switch-point model (onset and offset corresponding to the same developmental point in time) best fitted the second genotype. The results suggest that the plasticity of aphally is expressed before eggs hatch. Their consequences on the evolution of aphally are discussed. More generally, the methodology proposed here can be used to analyse variation in ontogenetic parameters of discrete traits.

Expression of the androgen receptor and 5 alpha-reductase type 2 in the developing human fetal penis and urethra

Normal penile development is dependent on testosterone, its conversion via steroid 5 alpha-reductase type 2 to dihydrotestosterone, and a functional androgen receptor (AR). The goal of this study was to investigate the distribution of AR and 5 alpha-reductase type 2 in the developing human fetal external genitalia with special emphasis on urethra formation. Twenty fetal genital specimens from normal human males (12-20 weeks gestation) were sectioned serially and stained by avidin-biotinylated peroxidase complex method with antigen retrieval. Stained sections throughout male genital development documented the expression of AR and 5 alpha-reductase type 2 in the phallus. Between 12 and 14 weeks of gestation, AR was localized to epithelial cells of the urethral plate in the glans, the tubular urethra of the penile shaft, and stromal tissue surrounding the urethral epithelium. In the fetal penis between 16 and 20 weeks gestation, the density of AR expression was greatest in urethral epithelial cells versus the surrounding stromal tissues. There was a characteristic pattern of AR expression in the glandular urethral epithelium between 16 and 20 weeks gestation. AR expression was greater along the ventral aspect of the glandular urethra than along the dorsal aspect of the urethral epithelium. The expression of 5 alpha-reductase type 2 was localized to the stroma surrounding the urethra, especially along the urethral seam area in the ventral portion of the remodeling urethra. These anatomical studies support the hypothesis that androgens are essential for the formation of the ventral portion of the urethra and that abnormalities in either the AR or 5 alpha-reductase type 2 can explain the occurrence of hypospadias.

Urethral seam formation and hypospadias

Knowledge of the formation of the normal male urethra may elucidate the etiology of hypospadias. We describe urethral formation in the mouse, show the similarities and relevance to human urethral development, and introduce the concept of the epithelial seam formation and remodeling during urethral formation. Three mechanisms may account for epithelial seam formation: (1) epithelial-mesenchymal transformation similar to that described in the fusion of the palatal shelves, (2) apoptosis, and/or (3) tissue remodeling via cellular migration. Urethral development in the embryonic mouse (14-21 days of gestation) was compared with urethral formation in embryonic human specimens (8-16 weeks of gestation) by using histology, immunohistochemistry, and three-dimensional reconstruction. The urethra forms by fusion of the epithelial edges of the urethral folds, giving a midline epithelial seam. The epithelial seam is remodeled via cellular migration into a centrally located urethra and ventrally displaced remnant of epithelial cells. The epithelial seam is remodeled by narrowing approximately at its midpoint, with subsequent epithelial migration into the urethra or penile skin. The epithelial cells are replaced by mesenchymal cells. This remodeling seam displays a narrow band (approximately 30 microns wide) of apoptotic activity corresponding to the mesenchymal cells and not to epithelial cells. No evidence was seen of the co-expression of cytokeratin and mesenchymal markers (actin or vimentin). Urethral seam formation occurs in both the mouse and the human. Our data in the mouse support the hypothesis that seam transformation occurs via cellular migration and not by epithelial mesenchymal transformation or epithelial apoptosis. We postulate that disruption of epithelial fusion remodeling, and cellular migration leads to hypospadias.

Complete diphallia associated with features of covered exstrophy

This report describes a 1-day-old boy with complete true diphallia associated with features of covered or pseudo-exstrophy and an anorectal malformation. The urinary bladder and rectum were single. A divided sigmoid colostomy was constructed at birth for the anorectal anomaly. Complete diphallia and its likely embryogenesis are discussed.

Penile anatomy under the pubic arch: reconstructive implications

PURPOSE

We have previously defined the anatomy of the neurovascular bundle in the normal and hypospadiac penis. These studies were based on analysis of the fetal penis distal to the pubic arch without total inclusion of the crural bodies. To our knowledge the neuroanatomy beneath the pubic arch has not been well described. We defined the nerve distribution under the pubic arch and the relationship of the nerves to the crural bodies, corporeal bodies and urethra of the penis.

MATERIALS AND METHODS

Eight normal human fetal penile specimens (at 17.5 to 29 weeks of gestation and 1 hypospadiac specimen at 32 weeks were serially sectioned and stained with Masson's trichrome, and the neuronal markers protein gene product 9.5 and S-100. These specimens were unique in that they contained the whole penis from the glans to the crural bodies beneath the pubic arch. Older specimens were decalcified before fixation. Computer reconstruction with commercially available graphics software allowed 3-dimensional analysis of the nerves and crural bodies in relation to the pubic arch and surrounding structures.

RESULTS

The nerves of the penile shaft and glans surrounded the corporeal bodies, extending from the junction of the urethral spongiosum to the classic 11 and 1 o'clock positions with a paucity of nerves at the 12 o'clock position in the dorsal midline. Beneath the pubic arch the nerves to the penis were an extension of the dorsal neurovascular bundle of the prostate. The nerves formed 2 bundles following a path just under the pubic arch in close proximity to the bone, superior to the urethra and medial to the origin of the crural bodies. The nerve bundles joined the corporeal bodies at the proximal origin, where the 2 crural bodies fused together. At this point perforating branches into the corporeal bodies from the cavernous nerves were documented. As the dorsal nerves joined the dorsal aspect of the corporeal bodies, they immediately began to fan out along the surface of the corporeal tissue to the junction of the urethral spongiosum. Three-dimensional reconstruction showed the relationship of the nerves to the pubic arch and urethra in multiple views.

CONCLUSIONS

A precise understanding of penile anatomy beneath the pubic arch and at the origin of the crural bodies is important for preserving neuronal structures. This anatomy is especially germane in children undergoing posterior urethral reconstruction secondary to trauma, intersex requiring feminizing genitoplasty and severe hypospadias.

The development of the fetal penis--an in utero sonographic evaluation

OBJECTIVE

To establish a nomogram for fetal penile length during gestation.

DESIGN

A prospective, cross-sectional study of normal singleton pregnancies.

SUBJECTS

Four hundred and nineteen male fetuses between 14 and 38 weeks were studied.

METHODS

Measurements of fetal penis length were performed by high resolution transvaginal ultrasonography between 14 and 17 weeks of gestation, and by transabdominal ultrasonography beyond 18 weeks of gestation.

RESULTS

Adequate penile length measurements were obtained in all 419 fetuses. Penile length as a function of gestational age was expressed by the regression equation: (square root) penile length (mm) = 0.277 + 0.121 x gestational age (weeks). The correlation coefficient, r = 0.967 was found to be highly statistically significant (P < 0.0001). The normal mean and the 90% prediction limits were defined. During the study period, we identified three fetuses with abnormalities involving penile development. Using the above reference data range, it has been shown that their penile length was below the lower limit.

CONCLUSIONS

The present data provide a normal range of fetal penile length from early stages of gestation that may allow intrauterine assessment of the development of the male external genitalia.

Urethral development in the fetal rabbit and induction of hypospadias: a model for human development

PURPOSE

To determine whether the development of the rabbit phallus would be an appropriate model of human phallic development, we evaluated the formation of the fetal rabbit phallus and attempted to induce hypospadias pharmacologically.

MATERIALS AND METHODS

New Zealand rabbit fetuses were obtained on gestational days 20 to 24, 26, 28 and 31. Sex was determined by gonadal morphology, and 6 fetuses were obtained at each age. The perineum was dissected, fixed, sectioned and stained with hematoxylin and eosin, and monoclonal antibodies against neuronal specific enolase. Two pregnant rabbits were treated with 10 mg./kg. finasteride orally daily between gestational days 19 and 28. The development of the external genitalia was compared in treated and untreated control rabbits.

RESULTS

The rabbit phallus contains 2 corpora cavernosa and dorsolateral nerves similar to the human. In male and female fetuses fusion of the urethral folds progressed in a proximal to distal sequence forming a seam at the point of ventromedial fusion. In male fetuses urethral fold and ventral preputial fusion continued more distally toward the glans compared to females. Thus, in mature males the urethral meatus and ventral prepuce extended to the tip of the phallus, whereas in females the urethral meatus opened on the proximal phallus and the prepuce was deficient ventrally forming a dorsal hood. Male offspring had a significantly larger anogenital distance postnatally than female offspring. In male fetuses exposed to finasteride urethral fusion did not extend distally and the prepuce was deficient ventrally. Also, male offspring exposed to finasteride in utero had a significantly shorter anogenital distance than females and untreated control males at all ages (p <0.05).

CONCLUSIONS

Fetal development of the rabbit phallus and urethra is homologous to the human. Although the gestational period is significantly shorter, the temporospatial pattern of external genitalia development is analogous in these species. Feminization of the rabbit urethra, hypospadias, can be induced by inhibiting 5alpha-reductase. Use of this animal model will allow further study of molecular mechanisms involved in urethral fusion and the evaluation of the pathophysiological processes of hypospadias.

Anatomy of the neurovascular bundle: is safe mobilization possible?

PURPOSE

We have previously defined the anatomy of the neurovascular bundle in the normal and hypospadiac penis. Historical experience suggests that mobilization of the neurovascular bundle is anatomically possible. We attempt to prove whether mobilization of the neurovascular bundle is safe and theoretically sound. Specific questions that will be addressed are does the neurovascular bundle send perforating branches into the corporal bodies; how far lateral does the dissection need to be before nerves are injured and exactly how deep into Buck's fascia must one go.

MATERIALS AND METHODS

A total of 35 normal human fetal penile specimens, gestational age 8 to 35 weeks, and 3 hypospadiac specimens, 33 to 41 weeks of gestation, were serially sectioned and stained with Mason's trichrome and the neuronal markers PGP 9.5 or S100. Computer reconstruction using commercial software and National Institutes of Health imaging allowed 3-dimensional analysis of the nerves, corporal bodies and glans.

RESULTS

Perforating nerves into the erectile bodies were not documented along the dorsal or lateral aspect of the tunica in any of the specimens studied. Only in the area of the crural bodies on the ventral lateral surface were nerves noted to pierce into erectile tissue. The neural network was extensive from the 11 and 1 to the 5 and 7 o'clock positions corresponding to the erectile tissue and urethral spongiosum junction. At this junction minor nerve branches were noted to perforate into the urethral spongiosum. A microscopic plane exists between the neurovascular bundle and tunica of the corporal bodies measuring 20 to 30 micro. in specimens greater than 30 weeks in gestation.

CONCLUSIONS

Perforating branches from the dorsal lateral neurovascular bundle do not exist based on serial step sectioning and microscopic examination of male genital specimens. Surgically it is possible to elevate the neurovascular bundle but the dissection needs to remain directly on top of the tunica albuginea to prevent neuronal injury. Small perforating branches into the urethral spongiosum may be injured with unknown significance. We continue to advocate plication in the nerve-free zone at the 12 o'clock position for correction of penile curvature.

Molecular analysis of external genitalia formation: the role of fibroblast growth factor (Fgf) genes during genital tubercle formation

The molecular mechanisms underlying the development of the external genitalia in mammals have been very little examined. Recent gene knockout studies have suggested that the developmental processes of its anlage, the genital tubercle (GT), have much in common with those of limb buds. The Fgf genes have been postulated as regulating several downstream genes during organogenesis. Fgf8 was expressed in the distal urethral plate epithelium of the genital tubercle (GT) together with other markers such as the Msx1, Fgf10, Hoxd13 and Bmp4 expressed in the mesenchyme. To analyze the role of the FGF system during GT formation, an in vitro organ culture system was utilized. It is suggested that the distal urethral plate epithelium of GT, the Fgf8-expressing region, regulates the outgrowth of GT. Ectopic application of FGF8 beads to the murine GT induced mesenchymal gene expression, and also promoted the outgrowth of the GT. Experiments utilizing anti-FGF neutralizing antibody suggested a growth-promoting role for FGF protein(s) in GT outgrowth. In contrast, despite its vital role during limb-bud formation, Fgf10 appears not to be primarily essential for initial outgrowth of GT, as extrapolated from Fgf10(−/−) GTs. However, the abnormal external genitalia development of Fgf10(−/−) perinatal mice suggested the importance of Fgf10 in the development of the glans penis and the glans clitoridis. These results suggest that the FGF system is a key element in orchestrating GT development.

Anatomical studies of the urethral plate: why preservation of the urethral plate is important in hypospadias repair

OBJECTIVE

To describe the detailed anatomy of the urethral plate in relation to its controversial role in hypospadias surgery.

MATERIALS AND METHODS

A newborn penis with proximal penile hypospadias and two fetal penises with distal shaft hypospadias were included in the study; 30 normal fetal penises served as the control. Specimens were embedded in paraffin and serially sectioned (6 microm) after formalin fixation. Every 10th section was stained with haematoxylin and eosin. Immunohistochemical staining for nerves (S100), smooth muscles (alpha-actin), blood vessels (factor VIII) and epithelium (cytokeratins 7, 14 and 18) were used on selected sections, with particular attention to the urethral plate. Masson's trichrome and Sirius Red stains were used to localize collagen.

RESULTS

There were extensive blood vessels, glands and smooth muscle under the urethral plate in the hypospadias specimens. These relatively well organized tissues corresponded to an abnormally formed corpus spongiosum. The glands underneath the urethral plate and adjacent to the normal urethra showed positive staining for cytokeratins 7 and 18, respectively (markers of endodermal origin) but were negative for cytokeratin 14 (a marker of ectodermal origin). Penile skin and urethral plate epithelium stained positively for cytokeratin 14 but not for cytokeratin 7 and 18. The urethral plate has a rich nerve supply, as determined by S100 staining. Collagen intensity under the urethral plate was no different from that in normal areas. Tunica albuginea stained intensely for type I and III collagen.

CONCLUSION

These results show that the urethral plate is well vascularized, has a rich nerve supply and an extensive muscular and connective tissue backing. These features may explain the lower complication rate with onlay flaps than with tube flaps. Therefore, from these anatomical findings, we continue to advocate preservation of the urethral plate and the onlay island flap for hypospadias reconstruction.

Fetal penile length

OBJECTIVE

To construct a reference range for fetal penile length.

METHODS

The length of the penis was measured during ultrasound assessment of 95 structurally normal male fetuses of gestational ages 16-38 weeks. Two fetuses with bladder outflow obstruction were also examined.

RESULTS

Fetal penile length increases significantly with gestational age, from a mean value of 6.0 mm at 16 weeks to 26.4 mm at 38 weeks. One fetus with urethral agenesis had a penile length on the 0.3rd centile.

CONCLUSIONS

Measurement of the fetal penis is easy and not time-consuming. In cases of bladder outflow obstruction, assessment of penile length assists in the differentiation between urethral agenesis and posterior urethral valves.

Prenatal karyotype and ultrasound discordance in intersex conditions

An infant born at 38 weeks' gestation with ambiguous genitalia had a prenatal 45X karyotype but an enlarged phallus on an ultrasound scan at 31 weeks' gestation. The newborn examination demonstrated penoscrotal hypospadias with chordee and two gonads palpable in the scrotum with a right hydrocele. Ultrasound showed a saccular structure containing debris behind the bladder. The postnatal karyotype was revealed to be 45X/46XY, with a pseudodicentric Y chromosome. Cystoscopy/genitography identified a uterus and a right fallopian tube, which were removed along with a dysgenetic right gonad. Biopsy of the descended left gonad revealed rare germ cells. The final diagnosis was 45X/46XY male pseudohermaphroditism with testicular dysgenesis. One should be aware of possible chromosomal mosaicism and combine the prenatal karyotype with the ultrasound genital findings to formulate an intersex differential diagnosis.