ANATOMICAL STUDIES OF HYPOSPADIAS

Neurovascular anatomy of the developing human fetal penis and clitoris

The human penile and clitoral development begins from a morphologically indifferent genital tubercle. Under the influence of androgen, the genital tubercle forms the penis by forming a tubular urethra within the penile shaft. Without the effect of the androgen, the genital tubercle differentiates into the clitoris, and a lack of formation of the urethra within the clitoris is observed. Even though there are similarities during the development of the glans penis and glans clitoris, the complex canalization occurring along the penile shaft eventually leads to a morphological difference between the penis and clitoris. Based on the morphological differences, the main goal of this study was to define the vascular and neuronal anatomy of the developing penis and clitoris between 8 and 12 weeks of gestation using laser scanning confocal microscopy. Our results demonstrated there is a co-expression of CD31, which is an endothelial cell marker, and PGP9.5, which is a neuronal marker in the penis where the fusion is actively occurring at the ventral shaft. We also identified a unique anatomical structure for the first time, the clitoral ridge, which is a fetal structure running along the clitoral shaft in the vestibular groove. Contrary to previous anatomical findings which indicate that the neurovascular distribution in the developing penis and clitoris is similar, in this study, laser scanning confocal microscopy enabled us to demonstrate finer differences in the neurovascular anatomy between the penis and clitoris.

What should be next in lifelong posterior hypospadias: Conclusions from the 2023 ERN eUROGEN and EJP-RD networking meeting

BACKGROUND

A congenital disease is for life. Posterior hypospadias, the severe form of hypospadias with a penoscrotal, scrotal, or perineal meatus, is a challenging condition with a major impact on lifelong quality of life.

AIM

Our network meeting is aimed to identify what is currently missing in the lifelong treatment of posterior hypospadias, to improve care, quality of life, and awareness for these patients.

METHODS

The network meeting "Lifelong Posterior Hypospadias" in Utrecht, The Netherlands was granted by the European Joint Programme on Rare Diseases-Networking Support Scheme. There was a combination of interactive sessions (hackathons) and lectures. This paper can be regarded as the last phase of the hackathon.

RESULTS

Surgery for hypospadias remains challenging and complications may occur until adulthood. Posterior hypospadias affects sexual function, fertility, and hormonal status. Transitional care from childhood into adulthood is currently insufficiently established. Patients should be more involved in defining desired treatment approach and outcome measures. For optimal outcome evaluation standardization of data collection and registration at European level is necessary. Tissue engineering may provide a solution to the shortage of healthy tissue in posterior hypospadias. For optimal results, cooperation between basic researchers from different centers, as well as involving clinicians and patients is necessary.

CONCLUSIONS

To improve outcomes for patients with posterior hypospadias, patient voices should be included and lifelong care by dedicated healthcare professionals guaranteed. Other requirements are joining forces at European level in uniform registration of outcome data and cooperation in basic research.

Tubularized incised plate urethroplasty and grafted tubularized incised plate urethroplasty: systematic review, meta-analysis and trial sequential analysis

Background

Hypospadias is one of the most common genital birth defects. There are around 300 various techniques available for the repair of hypospadias. This study aims to compare the reported outcomes of Tubularized incised plate urethroplasty (TIP) and Grafted TIP (GTIP) repair in children undergoing primary hypospadias repair.

Methods

This meta-analysisadhered to Preferred Reporting Items for Systematic Reviews and Meta-Analyses guidelines, and we framed our research question using the population, intervention, control and outcomes format. We conducted comprehensive electronic searches across various databases, employing a Boolean search strategy with predefined search terms. Only randomized controlled trials (RCTs) were included for quantitative analysis.

Results

Totally, 10 RCTs met our inclusion criteria for quantitative analysis. The results indicated that urethrocutaneous fistula, glans dehiscence, and stricture rates were comparable between the two groups. The incidence of meatal stenosis was found to be significantly lower in the GTIP group with a relative risk (RR) of 0.32 (95% confidence interval (CI) 0.15 to 0.67).

Conclusion

The coucomes UCF, glans dehiscence, and stricture rates were comparable between the two groups. Notably, the incidence of meatal stenosis was found to be significantly lower in the grafted TIP group. In terms of operative time, our quantitative synthesis demonstrated that the TIP group had a shorter operative time than the GTIP group with significant heterogeneity.

Spongioplasty with Buck's fascia covering dorsal inlay graft urethroplasty for primary hypospadias repair

INTRODUCTION

Neourethral covering is an essential technique for preventing complications such as fistula and glans dehiscence in hypospadias repairs. The spongioplasty has been reported for neourethral coverage about 20 years ago. However, reports of the outcome are limited.

OBJECTIVE

This study aimed to retrospectively evaluate the short-term outcome of spongioplasty with Buck's fascia covering dorsal inlay graft urethroplasty (DIGU).

METHODS

From December 2019 to December 2020, 50 patients with primary hypospadias (median age at surgery, 37 months; range, 10 months-12 years) were treated by a single pediatric urologist. The patients underwent spongioplasty with Buck's fascia covering dorsal inlay graft urethroplasty in single stage. The penile length, glans width, urethral plate width and length, and the location of the meatus of the patients were recorded preoperatively. The patients were followed up,complications noted, and postoperative uroflowmetries at the one-year follow-up time were evaluated.

RESULTS

The average width of glans was 12.92 ± 1.86 mm. A minor penile curvature was observed in all patients (≤30°). The patients were followed up for 12-24 months, and 47 patients (94%) were free from complications. A neourethra formed with a slit-like meatus at the tip of the glans, and the urinary stream was straight. Three patients had coronal fistulae (3/50) and no glans dehiscence, and the mean ± SD Q_max of postoperative uroflowmetry was 8.13 ± 3.8 ml/s.

DISCUSSION

This study estimated the short-term outcome of the DIGU covered using spongioplasty with Buck's fascia as the second layer in patients diagnosed with primary hypospadias with a relatively small glans (average width <14 mm). However, only a few reports emphasize spongioplasty with Buck's fascia as the second layer and the DIGU procedure performed on a relatively small glans. The major limitations of this study were its short follow-up time and the retrospective data collection.

CONCLUSIONS

Dorsal inlay graft urethroplasty combined with spongioplasty with Buck's fascia as coverage is an effective procedure. In our study, this combination had good short-term outcomes for primary hypospadias repair.

An objective hypospadias classification system

OBJECTIVE

Current approaches to classifying hypospadias severity are based on meatus position. These classification tools lack precise reflection on the degree of urethral hypoplasia and extent of urethral underdevelopment hence are not good representative of hypospadias severity. Here, an alternative classification system is introduced that objectively reflects the developmental pathology underlying this condition. The study goal was to appraise location of bifurcation in the corpus spongiosum (BCS) relative to the penile shaft as an indicator of hypospadias severity.

PATIENTS AND METHODS

Patients aged <18 years with primary hypospadias were included in the study. Urethral defect ratio (UDR) was calculated by dividing the extent of urethral defect (distance between the glandular knobs and BCS) relative to stretched penile length (SPL). Hypospadias severity was then categorized into three distinct grades (UDR <0.5, 0.5-0.99, ≥1.0). The Inter-Class Correlation (ICC) was evaluated to assess the intra- and inter-rater agreement between the reviewers of UDC ratio. Linear regression analysis was performed to estimate the correlation between UDC ratios and either plate objective scoring tool (POST) and Curvature degrees.

RESULTS

A total of 67 patients aged 12.3 ± 3.7 months with primary hypospadias were enrolled. UDR ranged between 0.2 and 1.3. A significant difference in hypospadias level was observed between UDR grades, which further correlated degree of curvature (P < 0.0001), urethral plate quality (P < 0.0001), and associated anomalies (P < 0.05). The Inter-Class Correlation (ICC) value to examine the intra- and inter-rater agreement between the two reviewers in UDC ratio was 0.998 (95% CI 0.998, 0.999). Regression analysis revealed that UDR and both POST and Curvature degree were significantly associated (P < 0.001).

CONCLUSIONS

A hypospadias severity scoring system based on embryological etiology and urethral hypoplasia and assessed relative to the penile shaft represents an objective, feasible, and consistent tool. These results clearly indicate that the reviewers have had excellent consistency/reliability across their consecutive readings. This new system can facilitate objective description of hypospadias-spectrum anomalies and thus support precise communication between individual surgeons and centers.

Phenotypic modulation of vascular smooth muscle cells in the corpus spongiosum surrounding the urethral plate in hypospadias

Hypospadias is an abnormal ventral development of the penis caused by incomplete virilization of the male genital tubercle. This study investigated the phenotypic modulation of vascular smooth muscle cells (VSMCs) in the corpus spongiosum surrounding the urethral plate in hypospadias. The urethral corpus spongiosum tissue was collected for HE, Masson and α-SMA immunohistochemical staining. Spongiosum VSMCs were cultured and identified by α-SMA fluorescence. qRT-PCR and Western blotting and fluorescence were performed. The results showed that the vascular lumen of the corpus spongiosum around the urethral plate was larger and that the vascular smooth muscle layer was thicker in hypospadias. The expression of the contractile markers α-SMA and Calponin 1 in VSMCs was decreased, the expression of the synthetic marker OPN was increased, and the transcription of the phenotypic switching factors SRF and MYOCD was decreased. The expression of Ki67, PCNA and BAX was increased, and the expression of Bcl-2 was decreased. The phenotype of corpus spongiosum VSMCs in hypospadias changed from the contractional type to the synthetic type. This phenotypic modulation was associated with increased proliferation and apoptosis rates. SRF and MYOCD may be the main factors mediating the phenotypic modulation of urethral corpus spongiosum VSMCs.

Experience with modified two stage inner preputial flap for repair of proximal hypospadias with chordee: A single institution study with intermediate follow up

PURPOSE

We present our modified technique of using the inner preputial flap to cover the penile shaft, while removing the subcutaneous tissue of the distal part of the flap to act similar to graft. Herein, we present our experience with modified two stage inner preputial flap for repair of proximal hypospadias with chordee.

PATIENTS AND METHODS

The current study was a single-institution retrospective study between January 2016 and December 2020. Thirty-one patients with proximal hypospadias with chordee were included and underwent our modified technique. We excluded re-operative hypospadias and incomplete follow-up cases (<6 month of follow up). Patient demographics, outcomes and complications in the form of fistula formation, diverticulum, metal stenosis, stricture formation and glans dehiscence were reviewed.

RESULTS

A total of 31 patients were included in the study and underwent our modified technique. The median age was 18 months (9-60) & IQR 15-25). The median follow up was 40 months. Overall, success was achieved in 24 cases (77.4%). Complications occurred in seven cases (22.6%) and included urethrocutanous fistula in three patients (9.7%), diverticulum in two patients (6.5.%), metal stenosis in one patient (3.2%) and glans dehiscence in one patient (3.2%).

CONCLUSION

Our technique provides a favourable outcome with a low complication rate for repair of proximal severe hypospadias.

LEVEL OF EVIDENCE

Case Series Study (Level IV).

Ultrasonographic Diagnosis of Fetal Hypospadias

Fetal hypospadias should be consider in a male fetus with a shortened penis, blunt bulbous tips, ventrally curved shaft with or without chordee and a typical fan shape stream of urinary jet under color Doppler under prenatal ultrasound examination. The more severe form is usually accompanied by other congenital abnormalities.

Anatomical study of hypospadias penis using magnetic resonance imaging in children

INTRODUCTION

To assess the various anatomical patterns of the hypospadias penis, anatomical and histological study of the penile tissues, planes, and vascular patterns, and imagings such as ultrasound of penis, elastography, and Magnetic resonance imaging (MRI) of penis have been described in the literature. All these have been done to attempt the identification of anatomical variations that may influence surgical outcomes. There are very limited MRI studies of hypospadias penis to look for the pristine anatomy.

OBJECTIVE

The objective was to identify anatomical variations in hypospadias penis such as the penile tissues and planes and the vascularity using MRI.

MATERIAL AND METHODS

The total number of patients enrolled was 24 from January 2019 to July 2020. This included all the cases of hypospadias at any location aged ≥5 years. MRI penis was done using 3T (3 Tesla) MRI scanner (GE Healthcare signa 3T Scanner machine) with 3 mm body coil slice thickness and the surface coil of 3 inches. Non-contrast images were taken using fast spin-echo sequences in sagittal, coronal, and transverse planes. The findings analyzed were: presence and distribution of penile tissue and fascial structures, urethral plate thickness, and penile vasculature.

RESULTS

The mean age was 7.62 ± 2.14 years. The types of hypospadias included were Coronal 1/24 (4.2%), Subcoronal 14/24 (58.3%), Distal penile 3/24 (12.5%), Midpenile 5/24 (20.8%) and Penoscrotal 1/24 (4.2%) (Summary Table 1). The mean urethral plate thickness was 1.33 ± 0.38 mm. The penile soft tissues were well visualized along with their fascial planes. The majority of patients (91.7%, 22/24) had Superficial Dartos vessels with both branches. Bulbourethral vessel was present in 18 (75.0%) cases but could not be visualized in the rest. Ventral and Lateral Dartos vessels were seen in 20 (83.3%) cases. Perforators distal to meatus were visualized in 21 (87.5%) cases and not visualized in 3 (1 each in Penoscrotal, Midpenile, and Coronal hypospadias). Collaterals at corona sulcus were visualized in 23 (95.8%) cases, at paraurethral spongiosum in 15 (62.5%) cases, and at dorsum in 22 (91.7%) cases.

CONCLUSION

3T MRI gives precise images in hypospadias with relation to the tissue and fascial planes of the penis. The vascular pattern visualization in these patients may be confirmed by the availability of a dedicated penile coil which will help to improve the resolution of the penile structures. Analyzing the penile vascular pattern and correlating it with surgical outcomes may aid the surgeon's knowledge of hypospadias, develop new surgical techniques and hence reduce complications.

DORSAL Plication Technique for the Treatment of Congenital Ventral Penile Curvature: Long-Term Outcomes of 72 Cases

BACKGROUND

A total of 78 patients aged 11 to 17 years were diagnosed with congenital ventral penile curvature and underwent surgery with the dorsal plication technique between 2005 and 2014.

AIM

To investigate the long-term outcomes of 72 patients who underwent dorsal penile plication for the treatment of congenital ventral penile curvature without hypospadias.

METHODS

In all cases, the intervascular space between the deep dorsal vein and dorsal artery was dissected, and tunical plication was carried out with non-absorbable 3-0 polyamide sutures and the complication and satisfaction rates of the patients were determined in the postoperative seventh year.

OUTCOMES

At the final postoperative follow-up, the patients' satisfaction with the operation was found to be 95.8%.

RESULTS

Shortening of the penis (0.5-1 cm) in five cases, recurrence with less than a 20-degree curvature in two cases, palpable sutures in two cases was observed and no patients reported erectile dysfunction.

STRENGTHS & LIMITATIONS

The limitations of our study can be considered as the absence of pharmacological erection in the preoperative evaluation, failure to evaluate penile length at the last postoperative follow-up due to the continued development of the penis, inability to evaluate erectile function at the beginning, postoperative erectile capacity being assessed in only some of the operated cases, all operations being performed by a single surgeon in the same center, and the absence of standardized questionnaires for postoperative satisfaction or adverse events.

CONCLUSION

According to the results of this study, dorsal plication is a relatively simple method with a low risk and high success rate for the treatment of congenital ventral penile curvatures. Akdemir F, Kayıgil Ö, Okulu E. DORSAL Plication Technique for the Treatment of Congenital Ventral Penile Curvature: Long-Term Outcomes of 72 Cases. J Sex Med 2021;18:1715-1720.

The effects of NONRATT008453.2 on autophagy in genital tubercle fibroblasts of rats with hypospadias induced by dibutyl phthalate

BACKGROUND

Hypospadias is a common birth defect that might be caused by inadequate fusion of the urethral folds in the process of male external genital development. We intended to discover the crucial long noncoding RNAs (lncRNAs) regulating autophagy from the gene expression profile of the genital tubercle (GT) of dibutyl phthalate (DBP) induced hypospadiac rats.

METHODS

Whole transcriptome resequencing was used to determine the expression of the total RNA in GTs and cultured fibroblasts obtained from GTs of DBP-induced hypospadiac male rat fetuses. Autophagosomes and autolysosomes were examined under a transmission electron microscope after overexpression of lncRNA NONRATT008453.2 in the fibroblasts by adenovirus transfection. Finally, the protein expression levels of Atg5, Beclin-1, Atg7, and the LC3A/B-II:LC3A/B-I ratio were detected in the fibroblasts by western blotting.

RESULTS

NONRATT008453.2 suppressed autophagy by promoting the expression of Atg7, but inhibited the expressions of Atg5, Beclin-1, and the LC3A/B-II:LC3A/B-I ratio in the GT fibroblasts.

CONCLUSIONS

NONRATT008453.2 may have an influence on autophagy in the fibroblasts of the GT in DBP-induced hypospadiac rats.

Ontogeny of estrogen receptors in human male and female fetal reproductive tracts

This paper reviews and provides new observations on the ontogeny of estrogen receptor alpha (ESR1) and estrogen receptor beta (ESR2) in developing human male and female internal and external genitalia. Included in this study are observations on the human fetal uterine tube, the uterotubal junction, uterus, cervix, vagina, penis and clitoris. We also summarize and report on the ontogeny of estrogen receptors in the human fetal prostate, prostatic urethra and epididymis. The ontogeny of ESR1 and ESR2, which spans from 8 to 21 weeks correlates well with the known "window of susceptibility" (7-15 weeks) for diethylstilbestrol (DES)-induced malformations of the human female reproductive tract as determined through examination of DES daughters exposed in utero to this potent estrogen. Our fairly complete mapping of the ontogeny of ESR1 and ESR2 in developing human male and female internal and external genitalia provides a mechanistic framework for further investigation of the role of estrogen in normal development and of abnormalities elicited by exogenous estrogens.

Estrogens and development of the mouse and human external genitalia

The Jost hypothesis states that androgens are necessary for normal development of the male external genitalia. In this review, we explore the complementary hypothesis that estrogens can elicit abnormal development of male external genitalia. Herein, we review available data in both humans and mice on the deleterious effects of estrogen on external genitalia development, especially during the "window of susceptibility" to exogenous estrogens. The male and female developing external genitalia in both the human and mouse express ESR1 and ESR2, along with the androgen receptor (AR). Human clinical data suggests that exogenous estrogens can adversely affect normal penile and urethral development, resulting in hypospadias. Experimental mouse data also strongly supports the idea that exogenous estrogens cause penile and urethral defects. Despite key differences, estrogen-induced hypospadias in the mouse displays certain morphogenetic homologies to human hypospadias, including disruption of urethral fusion and preputial abnormalities. Timing of estrogenic exposure, or the "window of susceptibility," is an important consideration when examining malformations of the external genitalia in both humans and mice. In addition to a review of normal human and mouse external genital development, this article aims to review the present data on the role of estrogens in normal and abnormal development of the mouse and human internal and external genitalia. Based on the current literature for both species, we conclude that estrogen-dependent processes may play a role in abnormal genital development.

The feasibility of urethral plate preservation in proximal and mid-penile hypospadias: sequential and anatomical approach to the repair

Background

The assessment of a child having hypospadias with chordee/ventral curvature (VC) and meatal position that appears to be proximal/mid-penile can be challenging with regard to the choice of chordee correction and type of urethroplasty. The feasibility of preservation of native urethral plate is dependent on these choices. Classically, urethral plate resection of the corpora is performed to correct severe VC, whenever VC is presumed to be due to short urethral plate. But VC is seen to persist in many such cases, in spite of this maneuver that commits the patient to a more complex reconstruction. The aim of the study was to analyze the variation in preoperative and intraoperative assessment of proximal and mid-penile hypospadias, with respect to severity and possible surgical options, in patients treated by a standard protocol of sequential and anatomical approach to repair. The other objective was to ascertain if “extensive ventral urethral detethering” (in all cases) and “urethral plate augmentation” (in select cases) could facilitate more anatomical repair in these cases, with urethral plate preservation and utilization for repair wherever feasible.

Results

Fifty-two children who underwent the specific protocol of repair during the 5-year period from January 2014 to December 2018 at a tertiary teaching institution were included in the study. The essential principles adopted for the surgery were as follows: (i) urethral plate preservation in all possible situations; (ii) “extensive ventral urethral detethering” up to the bulb, as a preliminary step, (iii) sequential correction of VC with urethral plate augmentation (in select cases); and (iv) selecting the optimal repair based on the following principles: (a) urethral plate tubularization, (b) urethral plate augmentation, and (c) urethral plate substitution. There was considerable difference in the preoperative and intraoperative assessment of meatal position, with 12 of the apparently mid-penile hypospadias being reclassified as distal penile after preliminary dissection. Three of the penoscrotal variants were regrouped as proximal penile and 6 of the proximal penile were regrouped as mid-penile type. Majority of cases which were deemed to require complex reconstruction on preoperative assessment could be treated by a single-stage procedure.

Conclusion

The meatal position is seen to shift distally in select cases of proximal or mid-penile hypospadias after thorough degloving, dartos release, and detethering of Buck’s fascia over ventral urethra. Urethral plate can be preserved for utilization in repair in many of these cases by augmenting the urethral plate, enabling a more anatomical neourethral reconstruction. Resection of urethral plate can be thus restricted to the most severe cases of VC.

Macro/microscopic distribution of the dorsal nerve of penis in human glans penis

This study aimed to elucidate the macroscopic and microscopic distributions of the dorsal nerve of penis (DNP) that provides the greatest sensitivity over the glans penis. The glandes of 23 penises of formalin-embalmed cadavers were investigated to confirm the macroscopic and microscopic distributions of the DNP within the glans penis by whole-mount Sihler's staining and histological sectioning. Superficial regions of the mid-glans were reconstructed in three dimensions to define the microstructure of terminal branches of the DNP that project towards the skin surface. A mean of 6.7 bundles of the DNP consisting of several nerve fibres converged linearly towards the distal end of the penis, rather than diverging laterally as they travelled. Lateral branches of the DNP extended linearly to the distal end with ramifications, while dorsomedial branches of the DNP gave off nerve fibres to the dorsum of the mid-glans and the corona. The intrastromal ramifications of the DNP were more developed in the distal half of the glans penis than the proximal glans containing the corpus cavernosum. These ramifications gave rise to radial nerve fibres that project towards the skin surface to form a plexiform network of terminal branches in the dermis. Linear projections of the main branches of the DNP throughout the glans and fine networks of terminal branches in the dermis were distinctly visualized in the human penis.

Development of the human prepuce and its innervation

Development of the human prepuce was studied over the course of 9-17 weeks of gestation in 30 specimens. Scanning electron microscopy revealed subtle surface features that were associated with preputial development, namely the appearance of epidermal aggregates that appeared to be associated with formation of the preputial fold. Transverse and sagittal sections revealed that the epidermis of the glans is considerably thicker than that of the penile shaft. We described a novel morphogenetic mechanism of formation of the preputial lamina, namely the splitting of the thick epidermis of the glans into the preputial lamina and the epidermis via the intrusion of mesenchyme containing red blood cells and CD31-positive blood vessels. This process begins at 10-11 weeks of gestation in the proximal aspect of the glans and extends distally. The process is likely to be androgen-dependent and mediated via androgen receptors strategically localized to the morphogenetic process, but signaling through estrogen receptor may play a role. Estrogen receptor alpha (ESR1) has a very limited expression in the developing human glans and prepuce, while estrogen receptor beta (ESR2) is expressed more broadly in the developing preputial lamina, epidermis and urethra. Examination of the ontogeny of innervation of the glans penis and prepuce reveals the presence of the dorsal nerve of the penis as early as 9 weeks of gestation. Nerve fibers enter the glans penis proximally and extend distally over several weeks to eventually reach the distal aspect of the glans and prepuce by 14-16 weeks of gestation.

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.

Reproductive tract biology: Of mice and men

The study of male and female reproductive tract development requires expertise in two separate disciplines, developmental biology and endocrinology. For ease of experimentation and economy, the mouse has been used extensively as a model for human development and pathogenesis, and for the most part similarities in developmental processes and hormone action provide ample justification for the relevance of mouse models for human reproductive tract development. Indeed, there are many examples describing the phenotype of human genetic disorders that have a reasonably comparable phenotype in mice, attesting to the congruence between mouse and human development. However, anatomic, developmental and endocrinologic differences exist between mice and humans that (1) must be appreciated and (2) considered with caution when extrapolating information between all animal models and humans. It is critical that the investigator be aware of both the similarities and differences in organogenesis and hormone action within male and female reproductive tracts so as to focus on those features of mouse models with clear relevance to human development/pathology. This review, written by a team with extensive expertise in the anatomy, developmental biology and endocrinology of both mouse and human urogenital tracts, focusses upon the significant human/mouse differences, and when appropriate voices a cautionary note regarding extrapolation of mouse models for understanding development of human male and female reproductive tracts.

Developmental mutant mouse models for external genitalia formation

Development of external genitalia and perineum is the subject of developmental biology as well as toxicology and teratology researches. Cloaca forms in the lower (caudal) end of endoderm. Such endodermal epithelia and surrounding mesenchyme interact with various signals to form the external genitalia. External genitalia (the anlage termed as genital tubercle: GT) formation shows prominent sexually dimorphic morphogenesis in late embryonic stages, which is an unexplored developmental research field because of many reasons. External genitalia develop adjacent to the cloaca which develops urethra and corporal bodies. Developmental regulators including growth factor signals are necessary for epithelia-mesenchyme interaction (EMI) in posterior embryos including the cloaca and urethra in the genitalia. In the case of male type urethra, formation of tubular urethra proceeds from the lower (ventral) side of external genitalia as a masculinization process in contrast to the case of female urethra. Mechanisms for its development are not elucidated yet due to the lack of suitable mutant mouse models. Because of the recent progresses of Cre (recombinase)-mediated conditional target gene modification analyses, many developmental regulatory genes become increasingly analyzed. Conditional gene knockout mouse approaches and tissue lineage approaches are expected to offer vital information for such sexually dimorphic developmental processes. This review aims to offer recent updates on the progresses of these emerging developmental processes for the research field of congenital anomalies.

The biomechanical properties of the urethra in boys with hypospadias: a preliminary study

PURPOSE

The ventral aspect of the penis in boys with hypospadias is composed of dysplastic tissue of the skin and the urethra. The aim of this study was to assess the pre-operative size and biomechanical properties of urethrae in boys with and without hypospadias using a more objective catheter-based system.

MATERIALS & METHODS

In this non-blinded clinical observation study, the study population consisted of 19 boys with hypospadias-the case group (median age 13.9 months [range: 12.2-21.3])-and seven boys without hypospadias-the control group (median age 8.5 months [range: 3.8-18.1]). Modified measurements of impedance were used to assess the size, compliance and viscoelasticity of the urethrae under stepwise increased pressures (between 0, 40 and 60 cmH₂O) using a customised Endolumenal Functional Lumen Imaging probe (EndoFLIP®).

RESULTS

The sizes of the urethrae in boys with hypospadias are variable but tend towards being narrower and less compliant than those of the control subjects i.e. median diameter for meatus urethra was 3.2 mm (range: 2.98-3.92) in the hypospadias group compared with 3.64 (range: 3.22-4.44) in the control group at 40 cmH₂O, and the median change in diameter at meatus urethra was 0.08 mm (range: -0.02 to 0.52) in the hypospadias group compared with 0.23 mm (range: -0.02 to 0.34) when the pressure was increased from 40 to 60 cmH₂O. This biomechanical analysis found that there was no significant viscoelasticity of the urethral meatus in both the groups, whereas the remainder of the urethral structure generally had viscoelastic properties in the control group, seen as a creep on the time/diameter curves (Figure). In the group of boys with hypospadias, evaluations of the urethrae revealed varying viscoelastic abilities, ranging from abilities that were comparable with those of the control subjects to no sign of viscoelasticity at all.

CONCLUSIONS

This study is the first to measure the biomechanical properties of the urethra in children, which might help to provide an understanding as to the structural and functional changes associated with hypospadias. The urethrae in the subjects with hypospadias were variable in diameter but tended to be narrower overall, especially in the distal portion of the urethra. Furthermore, the urethrae in boys with hypospadias were frequently less viscoelastic than those of controls.

CLINICAL RELEVANCE

The EndoFLIP® system may be a future way of objectively estimating the severity of a urethral obstruction and could potentially be included in the postoperative assessment of patients with signs of hampered voiding.

Immunohistochemical expression analysis of the human fetal lower urogenital tract

We have studied the ontogeny of the developing human male and female urogenital tracts from 9 weeks (indifferent stage) to 16 weeks (advanced sex differentiation) of gestation by immunohistochemistry on mid-sagittal sections. Sixteen human fetal pelvises were serial sectioned in the sagittal plane and stained with antibodies to epithelial, muscle, nerve, proliferation and hormone receptor markers. Key findings are: (1) The corpus cavernosum in males and females extends into the glans penis and clitoris, respectively, during the ambisexual stage (9 weeks) and thus appears to be an androgen-independent event. (2) The entire human male (and female) urethra is endodermal in origin based on the presence of FOXA1, KRT 7, uroplakin, and the absence of KRT10 staining. The endoderm of the urethra interfaces with ectodermal epidermis at the site of the urethral meatus. (3) The surface epithelium of the verumontanum is endodermal in origin (FOXA1-positive) with a possible contribution of Pax2-positive epithelial cells implying additional input from the Wolffian duct epithelium. (4) Prostatic ducts arise from the endodermal (FOXA1-positive) urogenital sinus epithelium near the verumontanum. (5) Immunohistochemical staining of mid-sagittal and para-sagittal sections revealed the external anal sphincter, levator ani, bulbospongiosus muscle and the anatomic relationships between these developing skeletal muscles and organs of the male and female reproductive tracts. Future studies of normal human developmental anatomy will lay the foundation for understanding congenital anomalies of the lower urogenital tract.

Development of the human penis and clitoris

The human penis and clitoris develop from the ambisexual genital tubercle. To compare and contrast the development of human penis and clitoris, we used macroscopic photography, optical projection tomography, light sheet microscopy, scanning electron microscopy, histology and immunohistochemistry. The human genital tubercle differentiates into a penis under the influence of androgens forming a tubular urethra that develops by canalization of the urethral plate to form a wide diamond-shaped urethral groove (opening zipper) whose edges (urethral folds) fuse in the midline (closing zipper). In contrast, in females, without the influence of androgens, the vestibular plate (homologue of the urethral plate) undergoes canalization to form a wide vestibular groove whose edges (vestibular folds) remain unfused, ultimately forming the labia minora defining the vaginal vestibule. The neurovascular anatomy is similar in both the developing human penis and clitoris and is the key to successful surgical reconstructions.

Distal urethral plate adhesions: New anatomical perspective in hypospadias

INTRODUCTION

We found midline epithelial adhesions in the glandar urethral plate in patients with hypospadias. After dissolution, a blind epithelized channel becomes visualized inside of the plate pointing to immature embryonic luminization. In addition it reveals that the epithelized surface of the distal urethral plate is larger than previously considered.

OBJECTIVE

To determine the incidence and extent of these new anatomical details of urethral plate in hypospadias patients.

METHODS

We prospectively assessed the detailed anatomy of the urethral plate in 72 consecutive patients with hypospadias. We recorded the presence of adhesions in the middle of the glandar urethral groove that can be easily dissoluted (dissolution line - D-line). We recorded the plate width before and after D-line dissolution, the presence of the hidden blind channel at continuation of D-line (channel type-A) and of the visible blind channel between D-line and urethral hypospadiac meatus (type-B) (Figure). In 62 patients, where the urethral plate tubularization was considered (Duplay, TIP), septs between channels were opened in the midline and a final width of the plate was measured by rolling the plate around a tube.

RESULTS

Midline adhesions (D-line) were found in all 72 patients. Mean length of D-line was 5.13 ± O.17 mm. Mean plate width before dissolution was 5.9 ± 0.15 mm, and after dissolution 7.8 ± 0.16 mm. A blind channel of type A was detected in 22 patients (31%), type B in 24 (33%), type A and B in 16 (22%), and none in 10 patients (14%). Mean final plate width after D-line dissolution and opening of septs between channels in 62 patients with urethral plate tubularization was 8.7 ± 0.15 mm.

DISCUSSION

The main contribution of our study is a new perspective of distal urethral plate anatomy that enables enlargement of the epithelized surface of the distal urethral plate by dissolution of the preexisting epithelized groove and opening of epithelized channels within the plate. To the best of our knowledge, this anatomical anomaly has not been described previously.

CONCLUSIONS

The distal urethral plate of all hypospadias patients is partially "folded" in the midline by epithelial adhesions of different depth and extent that may be easily dissoluted. In half of the patients (53%) the "folded" part of the plate continues proximally as a blind channel inside the urethral plate (type A channel). Opening of these structures together with the well-known urethral plate pits (type B channel) helps augment the width and the overall epithelized surface of the distal urethral plate.

An unanswered question in pediatric urology: the post pubertal persistence of prepubertal congenital penile curvature correction by tunical plication

OBJECTIVE

The aim of this study is to analyze post pubertal results of pre pubertal tunica albuginea plication with non-absorbable sutures in the correction of CPC.

MATERIALS AND METHODS

The files of patients who underwent tunica albuginea plication without incision (dorsal/lateral) were retrospectively reviewed. Patients younger than 13 years of age at the time of operation and older than 14 years of age in November 2015 were included. Patients with a penile curvature of less than 30 degrees & more than 45 degrees and penile/urethral anomalies were excluded. All of the patients underwent surgery followed by circumcision.

RESULTS

The mean age of patients at the time of the operation was 9.7 years (range, 6-13 years). The mean degree of ventral penile curvature measured during the operation was 39 degrees while it was 41 degrees in the lateral curvatures. All of the patients were curvature-free at the end of the operation. At the time of the follow-up examination, the mean age was 16.7 years (range, 14-25 years). Six patients had a straight (0-10 degrees) penis during erection and seven patients had recurrent penile curvatures ranging from 30 to 50 degrees.

CONCLUSION

Pre pubertal tunica albuginea plication of congenital penile curvature (30-45 degrees) with non-absorbable sutures performed without incision is a minimal invasive method especially when performed during circumcision. However, recurrence might be observed in half of the patients after puberty.

Altered SOX9 genital tubercle enhancer region in hypospadias

Human mutations in the SOX9 gene or its regulatory region can disrupt testicular development, leading to disorders of sex development (DSDs). Our previous work involving the genomic analysis of isolated DSD patients revealed a 78kb minimal sex determining region (RevSex) far upstream of SOX9 that was duplicated in 46,XX and deleted in 46,XY DSDs. It was postulated that RevSex contains a gonadal enhancer. However, the most highly conserved sub-region within RevSex, called SR4, was neither responsive to sex determining factors in vitro nor active in the gonads of transgenic mice, suggesting that SR4 may not be functioning as a testicular enhancer. Interestingly, SR4 transgenic mice showed reporter activity in the genital tubercle, the primordium of the penis and clitoris, a previously unreported domain of Sox9 expression. SOX9 protein was detected in the genital tubercle, notably in the urethral plate epithelium, preputial glands, ventral surface ectoderm and corpus cavernosa. SR4 may therefore function as a Sox9 genital tubercle enhancer, mutations of which could possibly lead to hypospadias, a birth defect seen in the DSD patients in the RevSex study. SR4 activity and the observed SOX9 expression pattern suggest that SR4 may function as a Sox9 genital tubercle enhancer. However, conditional ablation of Sox9 in the genital tubercle using Shh-Cre/+;Sox9^flox/flox mice revealed no genital tubercle abnormalities, possibly due to compensation by similar Sox factors. To conclude, we have identified a novel regulatory enhancer driving Sox9 expression during external genitalia development.

Correction of Residual Ventral Penile Curvature After Division of the Urethral Plate in the First Stage of a 2-Stage Proximal Hypospadias Repair

PURPOSE OF REVIEW

The first stage of a 2-stage proximal hypospadias repair involves division of the urethral plate and correction of any residual ventral penile curvature (VPC). Options to correct residual VPC include dorsal corporal shortening or ventral corporal lengthening techniques. This review discusses these options and suggests an approach to management.

RECENT FINDINGS

Recent reports of 2-stage proximal hypospadias repairs indicate low rates of recurrent VPC with either dorsal corporal shortening or ventral corporal lengthening. Dorsal corporal shortening with dorsal plication may be preferentially used for mild to moderate residual VPC after division of urethral plate and ventral corporal lengthening reserved for severe residual VPC. Ventral corporal lengthening with grafts has been associated with urethroplasty complications after the second stage hypospadias surgery. Ventral corporal lengthening with relaxing incisions of corpora has been reported, but concerns about adverse effects require longer term studies. Little guidance exists to choose the best technique for VPC correction during first stage hypospadias repair after division of urethral plate. Reported literature suggests good results with dorsal plication techniques and ventral corporal lengthening. A practical approach is to use dorsal plication techniques for mild to moderate residual VPC after division of urethral plate (<45°) and reserve ventral corporal lengthening for severe residual VPC (>45°).

Management of High-Grade Penile Curvature Associated With Hypospadias in Children

Penile curvature is a frequent feature associated with hypospadias with also a great variability of severity among each patient. While the low-grade curvature (<30°) can be relatively easily corrected by simple techniques like penile degloving and dorsal plication, severe cases often demand more complex maneuvers to manage it. A great number of surgical techniques have been developed to adequately correct curvatures greater than 30°; however, each one of them should be individualized to different patients and local conditions encountered. In this article, we will review the evaluation of the pediatric patient with penile curvature associated with hypospadias with a special attention to high-grade cases, their management, indications for surgical treatment, and several surgical options for their definitive treatment.

Management of 220 adolescents and adults with complications of hypospadias repair during childhood

Objective

The goal of hypospadias repair is to achieve normal voiding and good penile cosmesis with minimal complications. Some urethroplasties deteriorate from childhood to adolescence and late stage failures have been reported. We report our experience with adult patients who have had a previous repair during childhood and present with a late complication.

Methods

We reviewed the records of 220 patients aged 15–39 years old with a history of hypospadias repair who presented to our clinic. Forty-five patients with chordee, 39 with urethral strictures, 11 urethral fistulae, five with hairy urethras, three with urethral diverticula, and 117 patients with an abnormal glans or subterminal meatus were repaired.

Results

Median follow-up was 14 months. Two patients had persistent chordee. Island skin flap urethroplasty afforded one patient with a urethral fistula and another with a recurrent urethral stricture, while the buccal mucosa group had one fistula which healed spontaneously and two recurrent strictures. For the patients undergoing glanular repairs, seven had dehiscence or breakdown of the repair. All other operations were successful.

Conclusion

Complications of childhood hypospadias repair may present later in life as some urethroplasties deteriorate with time. We now recommend to parents of children with repaired proximal hypospadias to come for follow-up as their child transitions to adolescence.

Hypospadias anatomy: Elastosonographic evaluation of the normal and hypospadic penis

BACKGROUND

Hypospadias is one of the most common congenital anomalies in childhood. The aim of this study is to apply elastosonography on normal and hypospadic penis to verify the structural differences in tissues composition and stiffness.

MATERIALS AND METHODS

We analyzed medical chart of patients treated at our Institution for hypospadias during the period December 2005 and December 2014 (group 1). Other two groups were enrolled for this study: group 2- patients with hypospadias waiting for surgery and group 3-patients without hypospadias. Inclusion and exclusion criteria were created; all patients underwent penile ultrasound and elastosonography. Elastographic index of elasticity was defined as soft, medium-hard or hard. We assigned the value 1 to soft tissue, 2 and 3 to medium-hard and hard respectively.

RESULTS

During the study period 294 patients were treated for hypospadias. After reviewing medical chart 115 patients were considered for analysis (group 1). 22 patients were enrolled in group 2 and 38 patients were enrolled in group 3. Group 1: 7 proximal hypospadias, 29 penile hypospadias, 79 distal hypospadias. Patients with hypospadias had malformation also at corpus spongiosum and cavernosum respect to controls. Elastography showed a corpus spongiosum stiffness defined as medium-hard or hard in all cases of the pathologic group and soft in all the subjects of the control group (p < 0.05).

CONCLUSIONS

Elastosonography showed how the hypospadia anatomy is deeply altered, even in an anatomical area far from meatal abnormality: corpus spongiosum in hypospadic penis seems to be globally stiffer and less elastic and cavernous corpora are less developed.

Mouse hypospadias: A critical examination and definition

Hypospadias is a common malformation whose etiology is based upon perturbation of normal penile development. The mouse has been previously used as a model of hypospadias, despite an unacceptably wide range of definitions for this malformation. The current paper presents objective criteria and a definition of mouse hypospadias. Accordingly, diethylstilbestrol (DES) induced penile malformations were examined at 60 days postnatal (P60) in mice treated with DES over the age range of 12 days embryonic to 20 days postnatal (E12-P20). DES-induced hypospadias involves malformation of the urethral meatus, which is most severe in DES E12-P10, DES P0-P10 and DES P5-P15 groups, and less so or absent in the other treatment groups. A frenulum-like ventral tether between the penis and the prepuce was seen in the most severely affected DES-treated mice. Internal penile morphology was also altered in the DES E12-P10, DES P0-P10 and DES P5-P15 groups (with little effect in the other DES treatment groups). Thus, adverse effects of DES are a function of the period of DES treatment and most severe in the P0-P10 period. In "estrogen mutant mice" (NERKI, βERKO, αERKO and AROM+) hypospadias was only seen in AROM+ male mice having genetically-engineered elevation is serum estrogen. Significantly, mouse hypospadias was only seen distally at and near the urethral meatus where epithelial fusion events are known to take place and never in the penile midshaft, where urethral formation occurs via an entirely different morphogenetic process.

Proximal hypospadias: A persistent challenge. Single institution outcome analysis of three surgical techniques over a 10-year period

INTRODUCTION

The optimal treatment of proximal hypospadias remains controversial. Several techniques have been described, but the best approach remains unsettled.

OBJECTIVE

To evaluate and compare the complication rates of proximal hypospadias with and without ventral curvature (VC), according to three different surgical techniques: tubularized incised plate (TIP) uretroplasty, dorsal inlay graft TIP (DIG), and staged preputial repair (SR). It was hypothesized that SR performs better than TIP and DIG for proximal hypospadias.

METHODS

Single-center, retrospective chart review of all patients with primary proximal hypospadias reconstructed between 2003 and 2013. The DIG was selectively employed in cases with narrow urethral plate (UP) and deficient spongiosum. Extensive urethral plate (UP) mobilization (UPM), dorsal plication (DP) and/or deep transverse incisions of tunica albuginea (DTITA) were selectively performed when attempting to spare transecting the UP. Division of UP and SR was favored in cases with severe VC (>50°), which was often concurrently managed with DTITA if intrinsic curvature was present. For SR, tubularization of the graft was performed 6 months later.

RESULTS

A total of 140 patients were included. Tubularized incised plate (TIP), DIG, and SR techniques were performed in 57, 23, and 60 patients, respectively. The TIP and DIG techniques achieved similar success rates, although DIG was performed in cases of narrow and spongiosum-deficient plates. Reoperation rates with TIP and DIG techniques was 52.6% and 52.1% (NS). Urethro-cutaneous fistulas were seen in 31.5% and 13% of TIP and DIG techniques, respectively. Staged repair accomplished better results than both TIP and DIG techniques, despite being performed in the most unfavorable cases (reoperation rate 28%). After technical modifications, the DIG technique achieved similar outcomes of SR.

CONCLUSIONS

Proximal hypospadias remains challenging, regardless of the technique utilized for its repair. Urethro-cutaneous fistulas were more commonly seen after long TIP repairs. Approximately half of the patients undergoing long TIP and DIG procedures needed re-intervention, although the percentage decreased significantly with late modifications in the DIG group. Recurrence of VC after TIP and DIG techniques seemed to be a significant and under-reported complication. Staged repairs, despite being performed for the most severe cases, resulted in overall better outcomes.

Diethylstilbestrol-induced mouse hypospadias: "window of susceptibility"

This review presents published and novel results that define the programming window for diethylstilbestrol (DES)-induced abnormal development of the mouse penis. These data indicate that DES has its greatest effect during the period of most intense penile morphogenesis, namely postnatal days 0-15 (P0-P15). Pregnant mice and their neonatal pups were injected subcutaneously with 200 ng/gbw DES every other day from embryonic day 12-18 (DES E12-E18), postnatal day 0-10 (DES P0-P10), embryonic day 12 to postnatal day 10 (DES E12-P10), postnatal day 5-15 (DES P5-P15), and postnatal day 10-20 (DES P10-P20). Aged-matched controls received sesame oil vehicle. After euthanasia at 10, 15, 20 and 60 days, penises were analyzed by gross morphology, histology and morphometry. Penises of all 5 groups of DES-treated mice were reduced in size, which was confirmed by morphometric analysis of internal penile structures. The most profound effects were seen in the DES E12-P10, DES P0-P10, and DES P5-P15 groups, thus defining a DES "programming window". For all parameters, DES treatment from P10 to P20 showed the most mild of effects. Adverse effects of DES on the MUMP cartilage and erectile bodies observed shortly after the last DES injection reverted to normality in the DES P5-P15, but not in the E12-P10 and P0-P10 groups, in which MUMP cartilage and erectile body malformations persisted into adulthood, again emphasizing a "window of susceptibility" in the early neonatal period.

Clinical Study of 23 Male Patients with Congenital Ventral Penile Angulation without Hypospadias

Congenital ventral penile angulation without hypospadias is a rare disease and causes great anxiety to the parents. The aim of our study is the presentation of this disease, especially the indications of surgical treatment and the protocol applied in our clinic. We retrospectively studied 23 male patients aged 2.5 to 7 years old (av 5.2 y) with important penile angulation (over 45°) without hypospadias, treated during the past 15 years in our department. In 9 patients the cause was the skin chordee (fibrosis of the ventral part of the prepuce), in 4 the fibrotic fascia (incomplete development of dartos and Buck's fascia) and in 10 the disproportion of the corpora cavernosa. No case of congenital short urethra was reported. In our opinion, the appliance of the algorithm suggested by Donnahoo KK et al. in uncomplicated cases, along with the experience of the surgical team, results in satisfactory treatment and avoidance of complications.

Onlay foreskin flap anastomosed directly to the tunica albuginea: a short-term experimental study in rabbits

INTRODUCTION

In severe hypospadias, urethral plate division is necessary for curvature correction. To configure the new urethra, an approach has been described using a foreskin flap directly anastomosed in an 'onlay' fashion to the tunica albuginea of the corpora cavernosa. Results suggest that it is possible to use the corpus cavernosum albuginea as the posterior wall of the neourethra without the need of a dorsal graft.

OBJECTIVE

The present experimental study aimed to evaluate the histological characteristics and healing pattern of this procedure.

STUDY DESIGN

Sixteen New Zealand male rabbits were divided into two groups of eight animals. Eight animals underwent 1-cm longitudinal dorsal incision of the penile urethra and the edges were anastomosed to the tunica albuginea (Group 1). Eight other animals underwent complete excision of 1.0 cm of penile urethra. Urethroplasty was performed using a foreskin flap directly anastomosed as an onlay to the albuginea, as shown in the figure (Group 2). Sacrifice and histological assessment was performed 2, 4, 8 and 12 weeks postoperatively.

RESULTS

In Group 1, a mild inflammatory process was noted that became almost imperceptible at 12 weeks. Fibrosis was mild at all stages in this group. Over time, a regenerative epithelium covered the corpus cavernosum. Immunohistochemistry using specific CK-7 and CK-20 confirmed the presence of urothelium. No complications were microscopically detected in this group. Group 2 presented with a more intense inflammatory infiltrate, which also resolved over time. Fibrosis was slightly more intense in this group, especially in animals that had urethral strictures. Group 2 presented with three fistulas, two were associated with urethral stricture. Histological evaluation showed the presence of epithelization over the albuginea, which turned out to be similar to the normal urothelium over time and was confirmed by immunohistochemistry. Non-keratinized stratified squamous epithelium of the foreskin flap showed good integration to the urethra.

DISCUSSION

Microscopic analysis showed that inflammation, fibrosis and complications were similar to previous studies. At 12 weeks there was a well-developed epithelium similar to normal urethra, which was confirmed by immunohistochemistry; this was similar to what occurs in the TIP technique, as previously demonstrated. It was hypothesized that the epithelium regeneration developed from the urethral edges, as demonstrated in other experimental studies.

CONCLUSION

The albuginea was covered by mature urothelium after 12 weeks, which presumably grew from the urethral edges. The foreskin flap onlay that was directly anastomosed to the albuginea completely integrated and constituted the roof of the neourethra.

Canalization of the urethral plate precedes fusion of the urethral folds during male penile urethral development: the double zipper hypothesis

PURPOSE

We describe the "double zipper" mechanism of human male urethral formation, where the distal zipper opens the urethral groove through canalization of the urethral plate, and a second closing zipper follows behind and closes the urethral groove to form the tubular urethra.

MATERIALS AND METHODS

Anonymous human fetal genital specimens were acquired and gender was determined by polymerase chain reaction of the Y chromosome. Specimens were processed for optical projection tomography, stained with E-cadherin, Ki67 and caspase 3, and imaged.

RESULTS

Eight developing male fetal specimens from 6.5 to 16.5 weeks of gestation were analyzed by optical projection tomography, and an additional 5 specimens by serial sections. Phallus length ranged from 1.3 to 3.7 mm. The urethral plate canalized into a groove with 2 epithelial edges that subsequently fused. Ki67 staining was localized to the dorsal aspect of the urethral plate. In contrast, caspase 3 staining was not observed. The entire process was completed during a 10-week period.

CONCLUSIONS

The human male urethra appears to form by 2 mechanisms, an initial "opening zipper" that facilitates distal canalization of the solid urethral plate to form the urethral groove, which involves a high rate of epithelial proliferation (apoptosis not observed), and a "closing zipper" facilitating fusion of the 2 epithelial surfaces of the urethral groove, and thus extending the penile urethra distally. Improved knowledge of the molecular mechanisms of these processes is critical to understanding mechanisms of abnormal urethral development, such as hypospadias.

Anatomy of the clitoris and its impact on neophalloplasty (metoidioplasty) in female transgenders

The current management of female to male transgender surgery is based on the advances in neophalloplasty, perioperative care and the knowledge of the female genital anatomy, as well as the changes that occur to this anatomy with preoperative hormonal changes in transgender population. Since the clitoris plays the main role in female sexual satisfaction, its impact on the outcome in female to male transgender surgery is predictable. Although female genital anatomy was poorly described in majority of anatomical textbooks, recent studies have provided a better insight in important details such as neurovascular supply, ligaments, body configuration, and relationship with urethral/vaginal complex. This article aims to review current state of knowledge of the clitoral anatomy as well its impact on clitoral reconstruction in female to male sex reassignment surgery.