ANATOMICAL STUDIES OF HYPOSPADIAS

Development of the external genitalia and their sexual dimorphic regulation in mice

The study of the external genitalia is divided into 2 developmental stages: the formation and growth of a bipotential genital tubercle (GT) and the sexual differentiation of the male and female GT. The sexually dimorphic processes, which occur during the second part of GT differentiation, are suggested to be governed by androgen signaling and more recently crosstalk with other signaling factors. The process of elucidating the regulatory mechanisms of hormone signaling towards other signaling networks in the GT is still in its early stages. Nevertheless, it is becoming a productive area of research. This review summarizes various studies on the development of the murine GT and the defining characteristics of a masculinized GT and presents the different signaling pathways possibly involved during masculinization.

Long-term outcome of male genital reconstruction in childhood

Hypospadias, epispadias with or without exstrophy, and disorders of sex development are among the most common anomalies of genitalia that occur during childhood. Considering the tremendous effect of genitourinary reconstruction on adult life, the evaluation of the long-term results of different techniques of genitoplasty in pediatrics is of the utmost importance. After reviewing the literature, the authors summarize the available long-term outcomes of genitoplasty in childhood, specifically focusing on the cosmetic, psychosocial, psychosexual and functional results, and emphasize that, contrary to the widely available data on early outcomes of genital reconstruction in the pediatric population, very few well described controlled studies have evaluated the long-term effect of genitoplasty in puberty and adulthood, in the sense that the surgeon should describe the peroperative findings in more detail and also be more structured in evaluating the postoperative result at follow-up visits. Finally, the authors conclude that more attention should be paid to the impact of these techniques on cosmetic aspects and psychosexual development in these patients after puberty, as they play a crucial role in their adult quality of life.

How much does the midline incision add to urethral diameter after tubularized incised plate urethroplasty? An experimental animal study

PURPOSE

We objectively quantified the gain in urethral diameter and the effect of stenting after tubularized incised plate urethroplasty in a rabbit hypospadias model.

MATERIALS AND METHODS

We created a hypospadias model in 12 New Zealand white male rabbits by excising the ventral urethra. A 3 cm tattoo line was made longitudinally in the dorsal urethral plate midline. Two weeks later a 2 cm relaxing incision was made in the middle part of the tattooed line. The stretched incision width between the tattooed edges was measured, followed by urethral plate tubularization. Six rabbits were stented and 6 were nonstented. Two weeks later the animals were sacrificed and the distance separating the tattoo was measured at the midpoint of the tattooed line. Transverse sections at this point were examined histologically.

RESULTS

All animals survived the procedures. Stents were removed at 7 days in 4 rabbits and fell out in 2 at 4 and 2 days, respectively. The mean ± SD incision width of 5.5 ± 1.6 mm (range 3 to 8) at tubularization became 2 ± 0.5 mm (range 1 to 3) after healing (p <0.002). Mean width of the healed incision was 1.7 ± 0.4 (range 1 to 2) vs 2.3 ± 0.5 mm (range 1.5 to 3) in the nonstented and stented groups, respectively (p <0.06). Rabbits with a stenting duration of less than 7 days were excluded from the last analysis. Histologically all incisions healed completely with an intact epithelium.

CONCLUSIONS

The initial width of the midline relaxing incision significantly decreased after complete epithelialization. The average gain in urethral width was only 2 mm. Stenting appeared to increase the width of the healed incisions but not in a statistically significant manner.

Urinary flow patterns in infants with distal hypospadias

OBJECTIVE

To investigate preoperative urinary flow patterns in hypospadic infants and compare them to those from normal infant boys.

PATIENTS AND METHODS

Twenty-one boys (median age 14.0, range 12.8-21.6 months) referred for distal hypospadias surgery were compared to 19 healthy boys (median age 12.0, 9.2-19.8 months). In both groups a 14-mm transit-time ultrasound flow probe mounted around the base of the penis continuously registered uroflow.

RESULTS

Median maximum flow rate (Q(max)) was significantly lower in hypospadics (2.4 vs 4.4 ml/s, P < 0.01) while there was no difference in the voided volume per micturition (19.0 vs 21.0 ml, P 0.33). Flow curve pattern analysis revealed plateau-shaped curves in 31% of hypospadics compared to none in normal infant boys. Interestingly, dyscoordinated flow curves (interrupted, staccato, spike-dome) were less common in the hypospadics (36% vs 64%, P < 0.01). Meatal size did not correlate to Q(max) (rho = 0.26, P = 0.26).

CONCLUSIONS

Infants with hypospadias void with a lower Q(max) and a lesser degree of dyscoordination as compared to normal infant boys. It can be speculated that decreased urethral compliance may contribute to the lower Q(max) and may act as a silencer for dyscoordination.

A biomechanical, histological and biochemical study in an experimental rabbit hypospadias repair model using scanning acoustic microscopy

OBJECTIVE

To investigate the biomechanical, histological and biochemical properties of rabbit urethra at long-term follow up after hypospadias simulation and acute repair.

MATERIALS AND METHODS

Thirty-eight white New Zealand male rabbits underwent experimental creation of a hypospadias-like defect and acute repair (mobilization and advancement, tubularized incised posterior urethral plate (TIP), modified TIP) and sham operation. After 23 weeks all groups + controls underwent biomechanical, histological and biochemical assessments.

RESULTS

The mobilization and advancement group showed a higher stiffness compared to the TIP groups (P < 0.05) in the posterior urethra, whereas the TIP group was stiffer compared to the other two operative groups (P < 0.001) in the ventral urethra. In the dorsal urethra, the mobilization and advancement group and the modified TIP group had a higher collagen content compared to shams (P < 0.05). No differences in collagen content were found between groups in the ventral urethra. A correlation between acoustic and histological layers was found, partially related to collagen content.

CONCLUSION

The urethras had different microelastic properties in different layers of the dorsal and ventral urethra, with higher stiffness in the connective tissue layers surrounding and within the urethra. The repaired urethras had partially recovered their elasticity at micrometer resolution at long-term follow up. Scanning acoustic microscopy elucidated structure-function relationships at microscopic level in normal and operated urethra.

Hypospadias in a Friesian gelding

OBJECTIVE

To report clinical signs and management of hypospadias in a horse.

STUDY DESIGN

Clinical report.

ANIMAL

A 6-year-old, Friesian gelding.

METHODS

Partial phallectomy was performed to resolve contact dermatitis of the pelvic limbs and abnormal behavior during urination. Subsequent urethral meatal stenosis was treated by revision.

RESULTS

Hypospadias and chordee caused altered direction of urine flow, contact dermatitis of the pelvic limbs, and abnormal behavior. Partial phallectomy and subsequent revision after meatal stenosis resolved urine direction, flow and abnormal behavior.

CONCLUSIONS

Abnormalities of the urinary tract associated with hypospadias can result in urine-induced, contact dermatitis and distress during urination, but these complications can be resolved by partial phallectomy.

Hypospadias

Hypospadias results from abnormal development of the penis that leaves the urethral meatus proximal to its normal glanular position anywhere along the penile shaft, scrotum, or perineum. A spectrum of abnormalities, including ventral curvature of the penis (chordee), a hooded incomplete prepuce, and an abortive corpora spongiosum, are commonly associated with hypospadias. Advances in understanding of the causes of hypospadias and current approaches to the correction of hypospadias to provide a cosmetically and functionally satisfactory repair are the focus of this article.

Is tubularization of the mobilized urethral plate a better alternative to tubularization of an incised urethral plate for hypospadias repair?

INTRODUCTION

Trial of a new procedure of hypospadias repair based on the incorporation of the entire available innate urethral tissue for the formation of neo-urethra in patients with hypospadias.

MATERIALS AND METHODS

Fifteen consecutive children, nine with distal hypospadias and six with proximal hypospadias (all with severe chordee), whose parents consented to application of a new procedure of hypospadias repair, were the study subjects. This procedure is inspired by Cantwell Ransley procedure for epispadias repair and Snodgras procedure for hypospadias repair. The entire urethral plate was mobilized (i.e., lifted off the corpora) distal to the urethral meatus and was tubularized in two layers; inner urethral skin and outer spongiosal tissue, in Duplay fashion. The repair was reinforced with dartos vascularized flap. The skin incisions on the urethral strip are guided by the disposition of the spongiosal tissue underlying the urethral plate (rather than the conventional U-shaped incision on either side of hypospadiac urethral meatus). In the patients with proximal hypospadias with severe chordee urethral advancement was combined to achieve orthoplasty and a single stage hypospadias repair. The catheter was removed on tenth postoperative day.

RESULTS

Even in patients with proximal hypospadias with severe chordee, good single staged repair was achieved without resorting to dorsal plication that would have been necessary had any other methods based on the preservation of urethral plate was performed in these subjects. Therefore, the procedure was found to have an extended applicability to even those patients where tubularized incised urethral plate urethroplsty is not advised. All patients had good results (in 1 year follow-up), except in three early subjects of the series; two of whom developed minor urethrocutaneous fistulae (probably due to frank urinary leak secondary to repeated catheter blockade) and one developed partial glanular wound dehiscence.

CONCLUSIONS

Though the authors have an initial limited experience with this procedure, the procedure is likely to have a promising future due to its versatility and utilization of the entire urethral tissue.

[Hypospadias repair with Snodgrass' technique]

Retrospective study of 124 patients (average age: 3.8 years) with midpenile hypospadias: 48.3% (60 children), distal penile: 45.9% (57) and coronal 5.6% (7), of which the 25.8% (16) presented ventral curvature and the 4.8% (6) resulting from the complication of another previous technique. All of them were operated according to Snodgrass' technique, removing the catheter between the 6th and 7th day in most of them. The global rate of complications was of 12%: 9 fistulae (7.2%) and 6 meatal stenosis (4.8%). Aesthetic result was satisfactory in all cases, getting glans covered by foreskin in 57.3%.

Nerve sparing ventral clitoroplasty preserves dorsal nerves in congenital adrenal hyperplasia

PURPOSE

Masculinization of the female genitalia observed in patients with classic congenital adrenal hyperplasia often results in clitorimegaly. Reduction clitoroplasty is the most widely practiced corrective surgery for clitorimegaly, yet reservations about surgical intervention exist based on fears of nerve destruction during surgical removal of excess erectile tissue. In this study, we modified the reduction clitoroplasty and examined excised erectile tissue for the presence of dorsal nerves.

MATERIALS AND METHODS

We describe the development of the nerve sparing ventral clitoroplasty. Nerves were examined in situ using optical coherence technology. In addition, erectile tissue removed from 27 female patients with congenital adrenal hyperplasia was examined immunohistochemically for the presence of nerves by staining for neurofilament. Nerves outside of the tunica albuginea were counted and measured. Tissue from 2 adult females was also examined by immunohistochemistry.

RESULTS

Optical coherence technology visualized dorsal nerves in 3 patients with congenital adrenal hyperplasia (size 600 to 800 microm). In 4 of 27 patients undergoing nerve sparing ventral clitoroplasty, no dorsal nerve branches were visualized in excised erectile tissue. In another 18 patients 10 or fewer nerve branches were found. In patients who underwent nerve sparing ventral clitoroplasty 92% of dorsal nerves detected were 90 microm or less. In contrast, 88% of dorsal nerves found in the 2 adult specimens were 120 microm or greater. The maximum nerve fiber size observed in patient specimens was significantly smaller than the maximum nerve fiber size observed in control specimens.

CONCLUSIONS

Scarcity of large dorsal nerves in histological specimens excised using nerve sparing ventral clitoroplasty likely reflects their preservation within the congenital adrenal hyperplasia patients. This preservation is vital to future somatosensory and motor function of the clitoris.

HOXA13 directly regulates EphA6 and EphA7 expression in the genital tubercle vascular endothelia

Hypospadias, a common defect affecting the growth and closure of the external genitalia, is often accompanied by gross enlargements of the genital tubercle (GT) vasculature. Because Hoxa13 homozygous mutant mice also exhibit hypospadias and GT vessel expansion, we examined whether genes playing a role in angiogenesis exhibit reduced expression in the GT. From this analysis, reductions in EphA6 and EphA7 were detected. Characterization of EphA6 and EphA7 expression in the GT confirmed colocalization with HOXA13 in the GT vascular endothelia. Analysis of the EphA6 and EphA7 promoter regions revealed a series of highly conserved cis-regulatory elements bound by HOXA13 with high affinity. GT chromatin immunoprecipitation confirmed that HOXA13 binds these gene-regulatory elements in vivo. In vitro, HOXA13 activates gene expression through the EphA6 and EphA7 gene-regulatory elements. Together these findings indicate that HOXA13 directly regulates EphA6 and EphA7 in the developing GT and identifies the GT vascular endothelia as a novel site for HOXA13-dependent expression of EphA6 and EphA7.

Degloving and realignment--simple repair of isolated penile torsion

OBJECTIVES

To present the results of repairing congenital or acquired penile torsion by means of a simple surgical procedure that does not involve resection of corporeal tissue.

METHODS

Forty-six circumcised patients (mean age 27 months, range 6 to 119) presented with isolated penile torsion of a greater than 30 degree rotation. The surgical technique involved degloving the penile skin to the penoscrotal junction. Residual torsion was corrected using 5-6/0 polyglactin absorbable suture applied to the desired 12-o'clock position of the penile skin adjacent to the glans and to a location counter to the direction of the torsion in the degloved penile skin sleeve. A wedge of loose ventral penile skin was usually resected. The resultant tightening of the skin allowed for proper alignment of the penis and better cosmesis. The rest of the circumferential incision was closed using the same suture material. The success of the procedure was evaluated according to physician and parental satisfaction with the final outcome.

RESULTS

Thirty-seven patients were available for follow-up (mean 31 months, range 8 to 68). Satisfactory results were achieved in 35 (95%) of the 37 patients; the other 2 had residual torsion. Complications were minor and consisted of postoperative fever and a subcutaneous hematoma in 1 patient that resolved with conservative treatment.

CONCLUSIONS

The degloving and realignment procedure is a simple technique that may be applied safely and successfully in most cases of penile torsion.

Hypospadias and associated penile anomalies: a histopathological study and a reconstruction of the pathogenesis

Hypospadias is considered to be the result of inadequate fusion of urethral folds and, possibly, of canalization of a glandar epithelial cord during the formation of the spongy urethra. This theory had to be reconsidered because a recent study in normal human embryos has exposed such fusion and invagination as misconceptions. Autopsy specimens of five penises with hypospadias from foetuses and neonates were studied histologically. The findings complemented with data from the literature were correlated to the normal developmental process to reconstruct the pathogenesis of the disorder. Histopathological analysis revealed that the hypospadic orifice was the proximal part of a mucosal delta which revealed the structure of the roof and meatus of a flattened distal urethra. Branches of the raphe bordering the delta and terminating in prominent 'dog ears' had the characteristics of the transient urethral labia (folds). Associated curvature and torsion could be related to structural abnormalities of vascular structures, notably the distal corpus spongiosum, and fasciae predominantly proximal to the hypospadic orifice. Correlation with normal development indicated that hypospadias and associated anomalies are not caused by disturbed fusion or glandar invagination but by maldevelopment of a complex of primordial fascial and vascular tissue proximal to the urethral orifice which normally form the venter side of the penis by disproportionately strong proliferation and make the urethral orifice shift distalward. Insufficient growth may disturb that shift with the degree of deficiency determining the precise position of the urethral orifice, size of the urethral delta and defect of the prepuce. Shortage and/or poor organisation of these tissues explain curvature and, if asymmetrical, torsion, both of which can occur also with minimal urethral deformity or as congenital ventral curvature and torsion without hypospadias.

Tubularized incised plate (TIP) in previously operated (redo) hypospadias

OBJECTIVE

We report our experience of using the tubularized incised plate (TIP) technique for repair of hypospadias in patients who had undergone one or more failed attempts at repair.

METHODS

A total of 30 children (age range 2-10 years; mean 4.3 years) with hypospadias presented to our unit for redo hypospadias. The number of prior repairs was as follows: one in 17 patients, two in eight patients and three in five patients. The meatus was at the distal shaft in 19 cases, mid shaft in eight cases, and proximal shaft in three cases. Preoperatively 13 patients had fistulae, and none had residual chordee. The urethral plates were judged to be surgically altered in 11 patients and unaltered in 19 patients. The neourethra was then reconstructed using the Snodgrass TIP technique. Follow-up urethral calibration was performed to assess the results. All patients were discharged same day postoperatively. All patients were followed up at 1 week, 3 weeks, 6 weeks, 3 months, 6 months and 1 year. Patients were contacted in June/July 2005 and brought back for re-evaluation of the results.

RESULTS

The cosmetic and functional results were satisfactory as judged by the parents. Overall complications were encountered in 7 patients (23%). Complications included six fistulae, five were associated with meatal stenosis and one with infection. Stand alone meatal stenosis occurred in three other cases of which only one required intervention. Fistula repair was successfully performed 6 months later in five patients with associated meatoplasty. One case had a revised repair. One case required meatotomy.

CONCLUSION

The TIP procedure is a viable option with satisfactory cosmetic and functional results for the correction of a previously failed hypospadias repair.

Hypospadias: anatomy, etiology, and technique

Hypospadias is one of the most common congenital anomalies defined by abortive development of the urethral spongiosum, the ventral prepuce and in more severe cases penile chordee. The etiology of hypospadias remains unknown with environmental exposure in the form of endocrine disruptors the most likely explanation for the worldwide increase in incidence in the last three decades. There are five sequential steps for the successful repair of hypospadias: 1) Orthoplasty or penile straightening, 2) Urethroplasty, 3) Meatoplasty and Glanuloplasty, 4) Scrotoplasty, and 5) Skin Coverage. The major technical advances in hypospadias surgery that have improved surgical outcomes are 1) Preservation of the urethral plate, 2) Incision of the urethral plate, 3) Dorsal midline plication, 4) Deepithelized urethroplasty dartos flap coverage, and 5) Two stage alternative techniques. This article reviews the pertinent embryology, anatomy and the most common hypospadias reconstructive operations to accomplish a successful repair.

A Neuroanatomical Comparison of Humans and Spotted Hyena, a Natural Animal Model for Common Urogenital Sinus: Clinical Reflections on Feminizing Genitoplasty

PURPOSE

Surgical treatment of the common urogenital sinus phallus has been one of the most challenging areas in pediatric urology. To better understand the neuroanatomy of the common urogenital sinus phallus, we evaluated an animal model naturally having this condition, the spotted hyena, Crocuta crocuta. We compared the neuroanatomy of male and female humans and spotted hyenas using anatomical, immunohistochemical and 3D reconstruction techniques. We also examined the implications of the pattern of clitoral innervation for the unique challenges faced by female spotted hyenas, the only extant species of mammal that mates and gives birth through the clitoris.

MATERIALS AND METHODS

Three adult male and 3 female spotted hyenas were studied. With the animals under anesthesia gross anatomical examination was performed before and after artificial erection. Histological analysis was performed on one 95-day fetal male and female spotted hyena specimens, and on 18 human male and female fetal external genitalia specimens using antibodies raised against the neuronal marker S-100. Three-dimensional computer reconstruction using serial sections allowed analysis of the neuroanatomy of the penis, clitoris and common urogenital sinus of the fetal spotted hyena and human.

RESULTS

Compared to other mammals, the clitoris and penis of spotted hyenas were remarkably similar in size and configuration in the flaccid and erect states. Male and female hyenas had a single opening on the tip of the glans penis/clitoris. The basic anatomical structures of the corporeal bodies in both sexes of humans and spotted hyenas were similar. As in humans, the dorsal nerve distribution was unique in being devoid of nerves at the 12 o'clock position in the penis and clitoris of the spotted hyena. Dorsal nerves of the penis/clitoris in humans and male spotted hyenas tracked along both sides of the corporeal body to the corpus spongiosum at the 5 and 7 o'clock positions. The dorsal nerves penetrated the corporeal body and distally the glans in the hyena. In female hyenas the dorsal nerves fanned out laterally on the clitoral body. Glans morphology was different in appearance in both sexes, being wide and blunt in the female and tapered in the male.

CONCLUSIONS

The neuroanatomy of the male and female external genitalia in the spotted hyena, Crocuta crocuta, although grossly similar, has distinct anatomical and functional characteristics. The clitoris of the spotted hyena is a classic example of a natural animal model of a common urogenital sinus. The neuroanatomical characteristics of the spotted hyena may be a useful model to simulate the anatomy of common urogenital sinus anomaly in humans.

The midterm success rates of tubularized incised plate urethroplasty in reoperative patients with distal or midpenile hypospadias

To review the midterm results of tubularized incised plate (TIP) urethroplasty (Snodgrass method) in reoperative patients with distal or midpenile hypospadias. The results of TIP urethroplasty in 37 patients who had previously failed hypospadias repair were reviewed. Of the patients, 21 (56.8%) had coronal, 11 (29.7%) had subcoronal, and 5 (13.5%) had midpenile hypospadias. The mean age was 4.1 (2-16) years. Twenty-three patients had one operation and 14 patients had two operations previously. Of all the patients, 14 did not have a foreskin because of circumcision. The urethral plate had been disturbed in 6 patients, but there was not apparent scarring of the plate. Postoperative follow-up was 2.3 years with a range of 1.1-3.9 years. Genital examination, urethral calibration, and uroflowmetry were performed in control. Satisfaction of the families about the function and appearance of penis was also evaluated. Successful functional and cosmetic results were achieved in 29 patients (78.4%). All the families were happy with penile aesthetic appearance. The urethral plate seemed healthy at the operation in nine patients who had undergone TIP urethroplasty before and the outcomes were successful in eight of them. The operation was successful in 19/23 (82.6%) patients who had undergone one operation before and in 10/14 (71.4%) patients with two operations as well (P < 0.05). In addition, sufficient outcomes were obtained in also 11 of the 14 patients with circumcision. The success rate was higher in patients <5 years (P < 0.05). The rate was also higher during the recent period (2001-2003) since the experience we had increased (P < 0.05). TIP urethroplasty was unsatisfied in four of the six patients who had had disturbed urethral plate before and in five of eight patients who did not have sufficient amount of dartos tissue for flap to cover neourethra. Complication was observed in eight patients (21.6%): four had a pinpoint fistula, two had wound dehiscence, one had meatal stenosis, and one had mild meatal regression and a short neourethral stricture. All of these complications were repaired successfully at a later date. The mean hospital stay was 4.6 days. TIP urethroplasty provides good functional and cosmetic midterm outcomes in most of the reoperative patients with distal or midpenile hypospadias unless contraindicated by previous resection or gross scarring of the urethral plate. This procedure seems not to disturb the urethral plate and, therefore, it can be applied on reoperative patients who had undergone TIP urethroplasty before. It can also be used in a circumcised patient when there is a lack of foreskin.

Komplizierte Harnröhrenrekonstruktionen bei Erwachsenen und Kindern

The urethral reconstruction is a challenge in the adult, but even more in infant and young male patients. Good knowledge of the anatomy of the penis (blood supply and the course of the nerve fibers) with the availability of microsurgery suturing and instruments improved the outcome significantly. The growing knowledge opened the possibility to reconstruct complicate strictures with grafts. The buccal mucosa flap is one of those improvements, which made a tremendous impact to have a successful outcome. Recently we looked into the outcome of urethral reconstruction of long urethral strictures by using a buccal mucosa only flap. We used a modified technique for hypospadias repair to reconstruct coronar or subcoronar defects by meatal mobilization (MEMO). In cases with a long urethral stricture the success rate was over 90% with a mean follow up of 16 months. In all children the outcome with the MEMO-technique was successful without any major complication with a mean follow-up of 12.5 months.

Genitourinary Functions of Hoxa13 and Hoxd13

In the United States, Japan, United Kingdom, and Sweden, birth defects affecting the growth and development of the genitourinary (GU) regions are becoming increasingly prevalent, with incidences ranging as high as 1 in 125 live births. To understand the basis for these malformations, scientists have begun to examine the function of developmental genes in GU tissues. At the forefront of these investigations are studies examining the role of the 5' HOX proteins during the formation of the GU region. In this report we discuss what is known about HOXA13 and HOXD13 function during GU development, highlighting some of the cellular and molecular mechanisms controlled by these proteins during the GU formation. Finally, the translational benefits of identifying HOX target genes are discussed; first to explain the prevalence of some GU defects as well as a mechanism to facilitate their prevention in the birth population.

Comparison of hypospadiac and normal preputial vascular anatomy

PURPOSE

Data about the differences between the vascularization of normal and hypospadiac prepuce are lacking. We investigated the course of the preputial arterial blood vessels in normal controls and children with hypospadias by using transillumination, arterial methylene blue injection and 3-dimensional (3-D) reconstruction of serial histological sections focusing on arterial vessels.

MATERIALS AND METHODS

Prepuce of 48 normal controls and 15 children with hypospadias was transilluminated by a front and back lighting technique and then photographed. All of the normal and 12 of hypospadiac prepuces not used for urethroplasty or penile body skin reconstruction were removed. The blood vessels of normal prepuce were also identified after arterial injection of methylene blue. Selected prepuce of normal controls and children with hypospadias was serially sectioned, and arterial and venous vessels were histologically distinguished. A 3-D computer reconstruction of the arterial system of normal and hypospadiac prepuces was performed.

RESULTS

We confirmed the reliability of the transillumination technique to describe the arterial vascular anatomy of the prepuce by comparing the transillumination to methylene blue injection and 3-D reconstruction of histological sections. We classified the arterial vascular anatomy of normal prepuce as 1 artery predominant (41.67%), 2 arteries predominant (25%), H-type arching artery (12.5%) and net-like arterial system (20.83%). However, hypospadiac prepuce revealed a net-like arterial system more frequently (50%). We noted that the frequency of net-like arterial system was higher in more severe hypospadiac prepuce.

CONCLUSIONS

Understanding the differences between normal and hypospadiac prepuce vascular anatomy is germane to hypospadias surgery. The arterial blood supply of the hypospadiac prepuce is different than normal. A better knowledge of the vascular anatomy of the hypospadiac prepuce may improve the surgical results of hypospadias repair.

Hypospadias

Hypospadias results from abnormal development of the penis that leaves the urethral meatus proximal to its normal glanular position anywhere along the penile shaft,scrotum, or perineum. Hypospadiology is an evolving and expanding discipline that remains at the forefront of pediatric surgical innovation. Although modern experiments have begun to yield a deeper understanding of the genetic, hormonal, and environmental basis of hypospadias, the quest for a surgical procedure that consistently results in a straight penis with a normally placed glanular meatus has challenged surgeons for over two centuries. This article focuses on the advances in the understanding of the etiology of hypospadias and the current approaches to the correction of hypospadias.

Midline dorsal plication technique for penile curvature repair

PURPOSE

Most penile curvature repair techniques involve excision of the tunica albuginea and mobilization of the neurovascular bundles. Recent neuroanatomical studies of the neurovascular bundles have demonstrated the distribution of nerve fibers and identified the 12 o'clock position as the only nerve-free position. We present the results of penile curvature repair with the midline dorsal penile plication technique.

MATERIALS AND METHODS

A total of 45 penile plication procedures were performed in 43 pediatric patients, of whom 39 had mild to moderate and 4 had severe curvature. Eight patients had previously undergone penile curvature repair. After the induction of an artificial erection test a 4 or 5-zero polypropylene plication suture was placed at the point of maximal curvature at the 12 o'clock position.

RESULTS

Of patients with mild to moderate curvature 97% underwent a successful initial procedure. Satisfactory results were achieved in only 2 of the 4 patients with severe curvature. Two of the 3 initial failures were successfully reoperated using the same technique. The procedure was successful in all 8 patients who had previously undergone operation for curvature repair.

CONCLUSIONS

Midline dorsal penile plication is a safe, simple to perform procedure that achieves excellent results in patients with mild to moderate curvature. It is a useful technique in patients in who previous repairs have failed. We suggest other repair techniques for severe curvature.

Results of dorsal midline plication in children with penile curvature and hypospadias

OBJECTIVES

To present our initial results using dorsal midline (12-o'clock position) plication in children with penile curvature and hypospadias.

METHODS

Twenty-five children with hypospadias and ventral curvature confirmed after artificial erection underwent dorsal midline plication and hypospadias repair. Ventral curvature was corrected by making a 5 to 10-mm-long vertical incision through the tunica albuginea at the dorsal midline and approximating the outer edges of the incision with a monofilament polydioxanone stitch.

RESULTS

One plication suture was needed in 15 patients. In 8 patients with mid-shaft hypospadias and 2 with proximal penile hypospadias, two and three sutures were needed, respectively. In none of the patients was division of the urethral plate needed, except for one with proximal hypospadias. No complications were encountered during a mean follow-up of 9 months (range 5 to 34).

CONCLUSIONS

We believe that most cases of penile curvature with hypospadias can be corrected using dorsal midline plication of the tunica albuginea. Although long-term follow-up is necessary after puberty to confirm any erectile or sensory advantage, this approach might be considered whenever plication is to be performed.

Sensory innervation of normal and hypospadiac prepuce: possible implications in hypospadiology

Sensory innervation of the skin influences wound healing through the release of neuropeptides from the nerve endings. The purpose of this study was to investigate the differences in the sensory innervation of the normal and the hypospadiac prepuce. The prepuce from 10 healthy children undergoing routine circumcision and 10 age-matched children undergoing hypospadias repair were submitted for immunohistochemistry, using antibodies against protein gene product (PGP) 9.5, calcitonin gene-related peptide (CGRP), and substance P (SP). The hypospadiac prepuce was found to be hypo-innervated for PGP 9.5 and CGRP positive nerves when compared with the normal prepuce ( p<0.05). The number of SP-positive nerves were increased in the hypospadiac prepuce, but not to statistical significance ( p=0.06, confidence interval >95%). There may be differences in the sensory innervation of the normal and hypospadiac prepuce. These differences in tissue environment may partly explain the postoperative edema, poor wound healing leading to urethrocutaneous fistula (UF), and increased analgesia requirements in patients undergoing hypospadias surgery.

Anatomical studies of the mouse genital tubercle

BACKGROUND

To study the etiology of hypospadias, we propose the use of a mouse model, the embryonic mouse genital tubercle. In this study, we define the development of the mouse genital tubercle with special emphasis on urethral formation demonstrating anatomical similarities to human development.

MATERIALS AND METHODS

Serial sections of genital tubercles from embryonic male and female mice ages 14 to 21 days gestation from timed pregnant animals, newborn and adult mice were immunohistochemical stained with antibodies to E-cadherin, cytokeratins 7, 10, and 14. Patency of the urethral was assessed by india ink injection via the bladder. Urethral lumen morphology was determined by the creation of plastic resin cast. Surface morphology of the genital tubercle was defined by scanning electron microscopy.

RESULTS

India Ink injection into the bladder showed that the urethral lumen was patent from 14 days gestation. Plastic resin casts revealed that the male urethra was characterized by a S shaped curve, the presence of the bulbar urethral gland and a longer length than age matched females. The ontogeny of the genital tubercle development revealed two epithelial edges that subsequently touched and fused into the completed urethra. During development cytokeratin immunohistochemical staining demonstrated that the epithelial cells of the urethral lumen are of bladder origin and the surface cells of skin origin.

CONCLUSION

The functional and developmental anatomy of the mouse genital tubercle provides a useful model to study normal and abnormal human urethral development.

Bidirectional signaling mediated by ephrin-B2 and EphB2 controls urorectal development

Incomplete urethral tubularization (hypospadias) and anorectal abnormalities are two common and poorly understood birth defects that affect the extreme caudal midline of the human embryo. We now show that cell surface molecules essential for proper axon pathfinding in the developing nervous system, namely ephrin-B2 and the ephrin receptors EphB2 and EphB3, also play major roles in cell adhesion events that tubularize the urethra and partition the urinary and alimentary tracts. Mice carrying mutations which disrupt the bidirectional signals that these molecules transduce develop with variably penetrant severe hypospadias and incomplete midline fusion of the primitive cloaca. We further show that animals completely lacking ephrin-B2 reverse signaling present a fully penetrant failure in cloacal septation. This results in severe anorectal malformations characterized by an absence of the terminal-most hindgut (rectum) and formation of a fistula that aberrantly connects the intestines to the urethra at the base of the bladder. Consistent with an apparent requisite for both forward and reverse signaling in these caudal remodeling events, EphB2 and ephrin-B2 are coexpressed at the midline in the fusing urethral/cloacal endoderm and underlying lateral mesoderm of the urorectal septum that migrates toward the caudal midline as the cloaca septates. Our data thus indicate that B-subclass Eph and ephrin molecules play an important role in these clinically significant midline cell-cell adhesion and fusion events.

Time Course and Histology of Urethrocutaneous Fistula Formation in a Porcine Model of Urethral Healing

OBJECTIVE

Urethrocutaneous fistula is a well-known complication of hypospadias surgery and is reported in 5-10% of repairs. Using a previously described juvenile pig model, we present a histological analysis of the healing of the ventral aspect of the urethral repair and describe the histological mechanism of fistula formation.

MATERIALS AND METHODS

Twelve juvenile pigs underwent ventral, longitudinal urethral incision and closure over a 5-French feeding tube. The ventral aspect was closed in running fashion using two closure techniques and three suture types in each animal. Three animals were sacrificed on postoperative day 3, three on day 5, three on day 12, one on day 14, and two on day 21. Closure was one-layered incorporating urethral mucosa in the animals sacrificed on days 3, 5, and 21. An extra-mucosal suture technique was used in the group sacrificed on day 12. Sections of the penis were cut, paraffin embedded, and treated with Hematoxylin and Eosin staining.

RESULTS

Fistulae were seen in 12 specimens and in association with each suture type. Fewer sections of the extra-mucosal technique showed fistulization. Fistulae lined with immature epithelium were seen by day 5. Mature fistulae were observed by day 12. Skin epithelium and urethral mucosa migrated along suture tracts. By days 12 and 21, in addition to mature fistulae, several sections showed well-healed ventral repairs with clearly extramucosal suture tracts.

CONCLUSIONS

Fistula formation begins early in the healing process after ventral urethral repair. Incorporation of urethral mucosa in the ventral repair is a substrate for fistula formation with rapid migration of urethral mucosa and skin epithelium into suture tracts. The importance of a multi-layered repair and extra-mucosal suture technique are thus emphasized with respect to urethral repair. Whether the mucosal or dermal migration along suture tracts can be attenuated or prevented by changing the biochemical environment awaits further investigation.

Anatomical studies of the female genitalia: surgical reconstructive implications

Surgery for patients with genital ambiguity must be based on an accurate diagnosis, thorough understanding of the genital anatomy and realistic expectations for the patient, family and treating multi-specialty team. The goal is to create a functional and cosmetic outcome consonant with the gender assignment with the least amount of morbidity to the patient and family. An understanding of the normal genital neuroanatomy is essential for a successful surgical approach and outcome. Based on fetal human specimens, we have refined the three-dimensional relationship of the dorsal nerve of the clitoris, the female cavernosal nerve and the vaginal plexus. The surgical approach to patients with severe clitoral virilization should preserve erectile function and the neural innervation of the clitoris. When indicated, surgery should be performed in infancy to minimize psychological trauma and surgical complications from scarring. Herein, we review the neuroanatomy of the female genitalia and the implications for the rare patient who needs surgical reconstruction.

The development of the male genitourinary system: III. The formation of the spongiose and glandar urethra

It is generally agreed that the urethral plate disintegrates, resulting in the urethral groove. This is subsequently transformed into the urethra by fusion of the urethral folds, which flank its sides. Recently, the existence of such a groove and folds has been denied and this challenge to the long accepted existence of such folds is significant since hypospadias is considered to result from failure of their fusion. The present studies indicate that mesodermal fold formation and its subsequent subepithelial fusion across the midline plays an essential role in urethral tube formation. Disruption of this process readily explains common congenital abnormalities of the urethra.

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.

Anatomical Studies of the Fibroblast Growth Factor-10 Mutant, Sonic Hedge Hog Mutant and Androgen Receptor Mutant Mouse Genital Tubercle

OBJECTIVES

Congenital genital abnormalities have a diverse spectrum from hypospadias to cloacal anomalies. The molecular events in the normal and abnormal development of the genital tubercle (GT) are still obscure. Genetically engineered mice with specific gene deletions that affect genital anatomy are a useful tool to better understand the etiology of genital abnormalities. In this study, we compared the genital tubercle anatomy of the androgen receptor (AR) deficient, fibroblastic growth factor (FGF)-10 deficient and Sonic HedgeHog (Shh) deficient mutant male mice to that of the wild type male and female mouse.

MATERIALS AND METHODS

The lower pelvis of the androgen receptor deficient, FGF-10 deficient, Shh deficient mutant male and wild type male and female mouse at different gestational days (E13-21) and post natal ages (1 day-1 week) were studied. GTs were imaged, serially sectioned and stained immunohistochemically with antibodies raised against E-Cadherin, Cytokeratin 7, 10 and 14. Serial sections of the GTs were selected and three-dimensional computerized images were created to better elucidate the anatomy.

RESULTS

AR deficient mutant male mouse revealed a distinctive GT anatomy, different from both sexes. The corporal bodies and glans remained hypoplastic whereas the urethral spongiosa was more developed than the wild type female counterpart. This finding is consistent with the AR mutant mouse being a unique morphologic phenotype distinct from the normal male and female. FGF-10 deficient mutant male mouse revealed normal corporal bodies with failure of the urethral plate to fuse ventrally consistent with hypospadias. The Shh deficient mutant mouse demonstrated complete agenesis of GT outgrowth and a persistent cloaca.

CONCLUSION

Animal models bred by gene knockout technology or natural occurring mutants contribute to the basic understanding of normal and abnormal GT development. The anatomy of the these three mutant mice confirms the importance of the androgen receptor, FGF-10 and Shh in genital development.

Endocrine disruption and hypospadias

The complexity of human biology makes it impossible to know for certain if endocrine disruption accounts for human penile deformities. Toxicologists point out that an overall assessment of risk must include other factors in addition to exposure including absorption, metabolism, excretion, bioaccumulation and other chemical interactions (Harrison et al., 1997). Many skeptics observe lack of analytic ability to document contaminant levels during critical windows of exposure (Safe, 2000). Further, the environmental estrogens studied (DDT, PCB and bis-phenol A) are quite weak compared to the well studied potent estrogen DES which did not cause penile deformities (Joffe, 2001). While environmental estrogens may be unlikely in contributing to penile deformities, the antiandrogens (phthalates, vinclozolin and DDE) are more plausible is this regard, as maleness is critically dependent upon androgen action. Observers note that, in general, the environmental concentrations of persistent organochlorine compounds have been decreasing over the past two decades. Some feel that our current levels of exposure are too low and the potency of the anti-androgens too weak to account for any significant developmental genital effect (Williams et al., 2001). Caution and restraint are always reasonable in matters of data intrepretation. Past researchers were reassured that pthtalate esters were quite safe when they first were assessed for possible harmful effects on male fertility. Unfortunately it took different models, analyzing transgenerational effects, before it became crystal clear that these compounds can dramatically affect male genital development following experimental maternal exposure at dosages and concentrations currently present in most women. We can not now be so reassured that our male development is unaffected by any of the over 65,000 manmade organochlorine compounds on the planet. Multiple observations from diverse disciplines provide credible evidence that proliferation of xenobiotic chemicals can cause potentially disastrous unintended consequences for the male gender, and upon reflection, our species.