Androgen imprinting of the brain in animal models and humans with intersex disorders: review and recommendations

PURPOSE

Psychosexual development, gender assignment and surgical treatment in patients with intersex are controversial issues in the medical literature. Some groups are of the opinion that gender identity and sexual orientation are determined prenatally secondary to the fetal hormonal environment causing irreversible development of the nervous system. We reviewed the evidence in animal and human studies to determine the possible role of early postnatal androgen production in gender development.

MATERIALS AND METHODS

An extensive literature review was performed of data from animal experiments and human studies. RESULTS Many animal studies show that adding or removing hormonal stimulus in early postnatal life can profoundly alter gender behavior of the adult animal. Human case studies show that late intervention is unable to reverse gender orientation from male to female. Most studies have not permitted testing of whether early gender assignment and treatment as female with suppression/ablation of postnatal androgen production leads to improved concordance of the gender identity and sex of rearing.

CONCLUSIONS

Animal studies support a role for postnatal androgens in brain/behavior development with human studies neither completely supportive nor antagonistic. Therefore, gender assignment in infants with intersex should be made with the possibility in mind that postnatal testicular hormones at ages 1 to 6 months may affect gender identity. A case-control study is required to test the hypothesis that postnatal androgen exposure may convert ambisexual brain functions to committed male behavior patterns.

Androgen imprinting of the brain in animal models and humans with intersex disorders: review and recommendations

PURPOSE

Psychosexual development, gender assignment and surgical treatment in patients with intersex are controversial issues in the medical literature. Some groups are of the opinion that gender identity and sexual orientation are determined prenatally secondary to the fetal hormonal environment causing irreversible development of the nervous system. We reviewed the evidence in animal and human studies to determine the possible role of early postnatal androgen production in gender development.

MATERIALS AND METHODS

An extensive literature review was performed of data from animal experiments and human studies. RESULTS Many animal studies show that adding or removing hormonal stimulus in early postnatal life can profoundly alter gender behavior of the adult animal. Human case studies show that late intervention is unable to reverse gender orientation from male to female. Most studies have not permitted testing of whether early gender assignment and treatment as female with suppression/ablation of postnatal androgen production leads to improved concordance of the gender identity and sex of rearing.

CONCLUSIONS

Animal studies support a role for postnatal androgens in brain/behavior development with human studies neither completely supportive nor antagonistic. Therefore, gender assignment in infants with intersex should be made with the possibility in mind that postnatal testicular hormones at ages 1 to 6 months may affect gender identity. A case-control study is required to test the hypothesis that postnatal androgen exposure may convert ambisexual brain functions to committed male behavior patterns.

The role of insulin 3, testosterone, Müllerian inhibiting substance and relaxin in rat gubernacular growth

Transabdominal testicular descent is influenced by various anatomical and hormonal factors and is mediated by gubernacular enlargement and regression of the cranial suspensory ligament, but its mechanism remains controversial. The aim of this study was to determine which hormones have a direct effect on the proliferation of cells in the day 17 fetal rat gubernaculum in vitro, using an organ culture system. The effects of synthetic rat insulin 3 (INSL3), inactive INSL3, dihydrotestosterone (DHT), DHT+INSL3, human Müllerian inhibiting substance (hMIS), hMIS+INSL3 and human gene 2 relaxin were tested, together with co-culture with fetal rat testis. Cell proliferation was assessed using a bromodeoxyuridine labelling index. The results showed that MIS and relaxin have a mild effect on gubernacular growth, whilst INSL3 and DHT have a more marked effect. The combination of MIS+INSL3 showed an effect close to that of co-culture with testis. However, the most pronounced effect was caused by DHT+INSL3. RT-PCR analysis indicated that the fetal rat gubernaculum strongly expresses putative INSL3 receptors, weakly expresses MIS type II receptors and does not express relaxin receptors. In conclusion, a number of different hormones directly influence growth of the gubernaculum in vitro, including the recently reported hormone INSL3. INSL3 shows a direct stimulatory effect on the swelling reaction, while DHT and MIS may have roles in augmenting this growth.

Embryogenesis of tracheo esophageal anomalies: a review

The embryology of the normal esophagus and trachea is controversial. There are two main opinions regarding the role played by the tracheoesophageal (TE) septum. Similar controversy exists in explaining the embryology of anomalous TE development, mainly due to a lack of embryos demonstrating these anomalies at critical stages during development. Proposed theories can be divided into four main groups: intraembryonic pressure; epithelial occlusion; differential growth; and vascular occlusion. More recently, a new theory has been described based on analysis of anomalous TE development in adriamycin (doxorubicin)-exposed rat embryos. Impaired tracheal development, with the foregut developing into the trachea rather than the esophagus and associated with development of a dorsal pouch from the upper part of the foregut, gave rise to esophageal atresia with distal TE fistula. On the other hand, development of a ventral upper foregut pouch led to tracheal atresia. A laryngotracheo-esophageal cleft may result if no upper foregut pouches develop, with differentiation of the ventral half of the foregut into trachea and the dorsal half into esophagus. This review describes the basic theories of normal and abnormal TE development in mammalian embryos and presents new data related to this abnormality.

The development of the gubernaculum and inguinal closure in the marsupial Macropus eugenii

This study reports the developmental anatomy of testicular descent and inguinal closure of the tammar wallaby (Macropus eugenii) from birth to maturity. In females the ovary migrated caudally between days 10 and 20 after birth. The gubernaculum differentiates into the round ligament in the abdomen and extra-abdominally as the ilio-marsupialis muscle of the mammary glands. In males the testes migrated to the internal inguinal ring by day 20 post partum (pp), coinciding with the enlargement of the gubernaculum, and from the internal inguinal ring to the scrotum between days 20 and 65 pp. During descent there was an increase in the hyaluronic acid concentration in cells of the gubernaculum and scrotum. Development of the cremaster muscle began by day 10 pp on the periphery of the gubernaculum and its basic structure was completed by day 60 pp. After descent the inguinal canal closed between days 50 and 60 pp, but a small irregular lumen persisted, somewhat similar to that seen in the congenital scrotal hydrocoele of humans. Tammars have a hopping mode of locomotion and, like humans, are essentially bipedal. We suggest that inguinal closure evolved in these two species because their upright posture may otherwise lead to a high incidence of inguinal hernias.

Role of the gubernacular bulb in cremaster muscle development of the rat

The role of the gubernaculum during the inguino-scrotal phase of testicular descent remains controversial. Some authors propose involution and eversion while others suggest active migration, although the site of growth is unknown. We aimed to determine whether the gubernacular bulb is actively proliferating or regressing during inguino-scrotal testicular descent in the rat. Gubernacula were removed from Sprague-Dawley rats and congenitally-cryptorchid TS mutant rats. Animals (0, 3, 7, 10, and 11 days of age) were treated with bromodeoxyuridine (BUdR) 2 hr before they were killed. BUdR incorporation into newly synthesized DNA served as a marker of cell division. The gubernacula were histologically processed for hematoxylin-eosin (H&E) and immunoperoxidase staining. Four different areas within the gubernaculum were examined for BUdR-positive cells: area 1: plica gubernaculi (cord); area 2: pars infravaginalis gubernaculi (bulb); area 3: distal part of the cremaster muscle; and area 4: proximal part of the cremaster muscle. The rate of cell division for each of these areas was determined by counting the number of BUdR-positive cells per 100 cells. The highest rate of BUdR labeling in both types of rats was in area 2, which is the tip of the gubernacular bulb, and this was significantly greater (P < 0.0001) than in the gubernacular cord or developing cremaster muscle. The mitotic activity was also noted to be significantly greater (P < 0.0001) at the distal end of the cremaster muscle than at the proximal end. The amount of mitosis decreased significantly (P < 0.01) in areas 2 and 4 of the gubernaculum in Sprague-Dawley rats across the period studied. This trend was not observed in TS rats. Our results suggest that the bulb actively proliferates after birth, with possible differentiation into new cremaster muscle cells. We propose that the bulb is the growing end of the elongating gubernaculum, analogous to the growth of a limb bud.

The urethral plate--does it grow into the genital tubercle or within it?

OBJECTIVE

To determine whether the urethral plate grows into the genital tubercle or develops within it.

MATERIALS AND METHODS

Sprague-Dawley rat embryos were examined at 11-21 days of gestation and compared with available human embryo sections. Rat embryos were examined by a combination of light microscopy, dissection, serial histological section and immunohistochemistry.

RESULTS

In rat embryos the urethral plate extended to the tip of the genital tubercle from the earliest stages of genital tubercle development. The plate formed from adherence in the sagittal plane of the inner walls of the primitive cloacal cavity. The urethral plate continued to extend to the tip of the genital tubercle throughout penile development in the male and developed a lumen ahead of the advancing perineal mesenchyme. In the female the perineal side of the urethral plate disintegrated by massive apoptosis. This loss of perineal substance allowed the genital tubercle to collapse on itself and left the urogenital opening at the base of the genital tubercle. Human embryos also showed the presence of the urethral plate at the tip of the genital tubercle throughout genital tubercle development.

CONCLUSION

The urethral plate forms ab initio within the genital tubercle and extends to the tip; it does not grow into the genital tubercle as is often described. The contribution of ectodermal ingrowth to urethral development at the tip of the penis is minimal.

The cloacal plate: the missing link in anorectal and urogenital development

OBJECTIVE

To determine whether differences in the embryology of the anorectal and urogenital area, previously examined in sheep, pigs, rats, rabbits and guinea pigs, producing varying conclusions, may be secondary to differences in species development.

MATERIALS AND METHODS

Rat and human embryos were studied at the time of genital tubercle development and cloacal partition by standard serial-section histology, and by immunohistochemistry, dissection and scanning electron microscopy. The images obtained were compared with those previously reported for pig and sheep embryos.

RESULTS

The cloacal plate, a vertically orientated midline plate of epithelial cells in the caudal half of the genital tubercle, was the key structure that varied between the different species. In rats the plate maintained a vertical height along its length, while in humans and pigs it reverted to a two-layer membrane dorsally, shortly before it degenerated to expose both the anorectal and urogenital tracts. In sheep the plate was taller ventrally than in the other species but also reverted to a short membrane dorsally that exposed the hindgut when it degenerated. The anterior part of the cloacal plate persisted in all embryos as the urethral plate, which then participated in the formation of the urethra in the male and the vestibule in the female. The animal that most closely resembled humans in anogenital development was the pig.

CONCLUSIONS

The cloacal plate is the key to understanding early anorectal and urogenital development and yet it is barely recognized in published reports. An appreciation of its relevance helps to explain the variations in the described embryology of the region, and is mandatory when interpreting embryological findings in animal models of human anomalies. Given the similarities between porcine and human development, the pig may be the most legitimate animal model for the study of anorectal and urogenital anomalies in humans.

In vitro analysis of esophageal atresia using a whole-embryo culture system

BACKGROUND/PURPOSE

Administration of Adriamycin to pregnant rats leads to the development of esophageal atresia with tracheo-esophageal fistula. This defect arises from failure of the trachea to develop normally from the primitive foregut; instead,the upper foregut differentiates into trachea, then continues to the lower esophageal segment as a tracheo-esophageal fistula. Our aim was to explore the possibility of growing Adriamycin-exposed embryos using a whole-embryo culture technique and to determine whether or not esophageal atresia with tracheo-esophageal fistula could be prevented in an Adriamycin-treated rat model.

METHODS

Rat embryos were exposed to Adriamycin in utero on days 6 - 9 of gestation, removed on day 10 and grown in vitro as described by New (11) for 48 hours using 100% serum from animals not exposed to Adriamycin.

RESULTS

Thirty Adriamycin-exposed embryos were grown in vitro using normal serum. Histologic assessment of tracheo-esophageal development showed that 14 embryos had normal development, while 16 developed esophageal atresia.

CONCLUSIONS

Growth of Adriamycin-exposed embryos was successful using "whole-embryo culture technique"; abnormal tracheo-esophageal development could in some cases be altered by removing the embryos at day 10 and exposing them to normal serum for 48 hours.

Gubernacular development in Müllerian inhibiting substance receptor-deficient mice

OBJECTIVE

To determine, in mice with disrupted Müllerian inhibiting substance (MIS) receptor genes, whether MIS affects gubernacular development; MIS causes Müllerian duct regression and is proposed to be involved in the first stage of testicular descent, because gubernacular development is abnormal in humans with persistent Müllerian duct syndrome.

MATERIALS AND METHODS

Ten wild-type, 11 heterozygotic and 12 homozygotic mice for MIS receptor mutations were killed at 17.5 or 18.5 days after conception or at birth, to provide serial sagittal sections of the pelvis. The amount of cremaster muscle, mitotic bodies in the gubernacular bulb, and gubernacular size were quantified by computer analysis (four mice/group).

RESULTS

Müllerian ducts were present in the homozygous mutants, partially present in the heterozygotes and absent in the wild-type controls. All mice had descended testes. The cremaster muscle was significantly less developed in homozygous mutants than in wild-type controls (P < 0.001) and heterozygotes (P < 0.01) at birth. The mitotic index between the gubernacula of all groups was indistinguishable. There was no statistical difference in gubernacular area amongst the groups. Poor cremaster muscle development in homozygous mutants gave the muscle a loose mesenchymal appearance.

CONCLUSIONS

Although there was an observable effect on cremaster muscle development in these mutant mice, gubernacular development and testicular descent were otherwise normal, and thus there must be other reasons for the observed differences in humans with persistent Müllerian duct syndrome.

Clusters containing open-shell molecules: minimum-energy structures and low-lying isomers of ArnCH (X 2 pi), n = 1 to 15

The size evolution of the equilibrium structures of open-shell ArnCH (X 2 pi) Van der Waals clusters is investigated for n = 1 to 15. We describe a method for combining pair potentials for Ar-CH and Ar-Ar interactions to obtain potential energy surfaces for ArnCH clusters. For each cluster size considered, the global and a few energetically close local minima are calculated using simulated annealing followed by a direct minimization scheme. Ar2CH is found to have an unusually stable planar structure, which persists as a motif in larger ArnCH clusters and has a strong effect on their optimal geometries. The lowest-energy isomers of ArnCH with n = 3 to 11 have all Ar atoms in a shell around CH. The only exception is Ar4CH, where the fully solvated isomer is 3 cm-1 higher in energy than the optimal isomer with CH bound to the surface of the Ar4 tetrahedron. For n = 7 to 11, the minimum-energy structure of ArnCH derives from the global minimum of the Arn + 1 cluster, by replacing the Ar atom at the bottom of the pentagonal bipyramid with CH. The lowest-energy structure of Ar12CH is that of the optimal icosahedral Ar13 cluster, with CH replacing one of the Ar atoms on the cluster surface. This structure supports the proposition based on the spectroscopic data, that for ArnCH clusters with about 10 to 50 Ar atoms CH resides on the surface of Arn.

Slow transit constipation in children

Patients with chronic constipation that fails to respond to treatment remain a challenge for paediatricians and surgeons. Ongoing work in our institution suggests that a number of children with intractable symptoms have slow transit constipation, which has only been described recently in paediatrics. Common features of slow transit are: delayed passage of the first meconium stool beyond 24 h of age, symptoms of severe constipation within a year, or treatment-resistant 'encopresis' at 2-3 years, soft stools despite infrequent bowel actions, and delay in colonic transit on a transit study. A proportion of children with slow transit constipation have an abnormality of intestinal innervation associated with the dysfunctional colonic motility, recognized as intestinal neuronal dysplasia (IND). Intestinal neuronal dysplasia type B, the most common variant of IND, is defined on rectal biopsy by hyperplasia of the submucosal plexus. On laparoscopic colon muscle biopsy, many specimens show reduced numbers of excitatory substance P-immunoreactive nerve fibres in the circular muscle. Functional markers of the nerves allow new diagnostic criteria to be developed which may also allow a more rational approach to treatment. The aetiology remains obscure and the optimal management poorly defined, although subtotal colectomy, proximal colostomy or appendicostomy (for antegrade enemas) have been tried. Once the anatomy and physiology of the colon in children with slow colonic transit is better understood, we will have defined not only a new form of constipation, but also will be able to consider new therapies.

Chemical synthesis and biological activity of rat INSL3

The recently identified protein, insulin 3 (INSL3), has structural features that make it a bona fide member of the insulin superfamily. Its predicted amino acid sequence contains the classic two-peptide chain (A- and B-) structure with conserved cysteine residues that results in a disulphide bond disposition identical to that of insulin. Recently, the generation of insl3 knockout mice has demonstrated that testicular descent is blocked due to the failure of a specific ligament, the gubernaculum, to develop. The mechanism by which INSL3 exerts its action on the gubernaculum is currently unknown. The purpose of this study was to, for the first time, synthesize rat INSL3 and test its action on organ cultures of foetal rat gubernaculum. INSL3 also contains a cassette of residues Arg-X-X-X-Arg within the B-chain, a motif that is essential for characteristic activity of another related member of the superfamily, relaxin. Hence, the relaxin activity of rat INSL3 was also tested in two different relaxin bioassays. The primary structure of rat INSL3 was determined by deduction from its cDNA sequence and successfully prepared by solid phase peptide synthesis of the two constituent chains followed by their combination in solution. Following confirmation of its chemical integrity by a variety of analytical techniques, circular dichroism spectroscopy confirmed the presence of high beta-turn and alpha-helical content, with a remarkable spectral similarity to the synthetic ovine INSL3 peptide and to synthetic rat relaxin. The synthetic rat INSL3 bound with very low affinity to rat relaxin receptors and had no activity in a relaxin bioassay. Furthermore, it did not augment or antagonize relaxin activity. The rat INSL3 did however induce growth of foetal rat gubernaculum in whole organ cultures demonstrating that INSL3 has a direct action on this structure.

Antegrade continence enemas in the treatment of slow-transit constipation

BACKGROUND/PURPOSE

Children with anorectal dysfunction can now be treated by antegrade continence enema (ACE), as described Malone et al. Those with idiopathic constipation, however, are not thought to be suitable for this treatment. Over 150 children attend the authors' department with proven slow transit constipation (mostly proven on nuclear transit/X-ray study), and the authors reviewed the outcome in the 40 of these who have had the ACE procedure. Families completed a questionnaire and attended interview with an independent assessor.

METHODS

Of the 40 patients, 32 patients were assessed. Follow-up ranged from 3 to 54 months (median, 18 months) and age ranged from 5 to 17 years (median age, 10 years). Three of 32 stomas were no longer in use. Frequency of soiling was reduced significantly in 20 patients, and a further 6 patients were clean (P <.01). Abdominal pains were relieved significantly (P <.05), and appetite and mood improved.

RESULTS

Stomal complications were frequent, (stenosis in 16 of 29, mucus leak in 20 of 29, fecal leak 3 of 29, catheter-related pain in 20 of 29). Slow evacuation (12 of 29) and pain with enema (17 of 20) also were common.

CONCLUSION

Malone appendicostomy does improve the well being of patients with slow transit constipation, but the advantages are less dramatic than in children with normal motility.

The suspensory ligament of the clitoris: connective tissue supports of the erectile tissues of the female urogenital region

We aimed to define the gross anatomy of the supporting structures of the clitoris. We performed a dissection of the perineum of a series of 22 female and four male cadavers. Specific dissection of the clitoral and penile suspensory ligament complex was performed in four female and two male cadavers. Serial written observations and photography were used to document the findings. Our findings were then compared with the anatomical description of these structures in the historical and current anatomical literature. The suspensory ligament of clitoris consistently displayed two components: a superficial fibro-fatty structure extending from a broad base within the mons pubis to converge on the body of the clitoris and extending into the labia majora: in addition there is a deep component with a narrow origin on the symphysis pubis extending to the body and the bulbs of the clitoris. The supporting structures of the clitoris are more substantial and complex than previously described. Their shape, extent, and orientation are different from analogous structures of the penis, the suspensory ligament of which was found as described in the literature.

Early development of the gubernaculum and cremaster sac in estrogen receptor knockout mice

AIM exogenous estrogen causes gubernacular atrophy and cryptorchidism in fetal rodents. Mice with an estrogen receptor-alpha (ERalpha) disrupted gene mutation (alphaERKO) were studied to determine whether ablation of endogenous estrogen action, through ERalpha, had an effect on gubernacular development. Serial sagittal sections were made of the pelvis in fetal and day 7 postnatal wild-type and alphaERKO mice with the estrogen receptor-alpha "knockout" gene mutation. Wild-type (n = 24), heterozygote (n = 13) and alphaERKO mice (n = 12) were sacrificed at 16, 17 and 18 days fetal life and at 7 days postnatally. The size of the gubernaculum, cremaster muscle, cremaster sac, and the width of the sac at both ends in day 7 mice were quantitated by computer analysis. Visually and statistically the ERKO mice could not be separated from the wild-type mice during fetal life. At day 7 postnatally, a thicker cremaster sac was noted morphologically, and also a statistically significant difference was seen in the width of the cremaster sac at the sac's tip. Sac area, cremaster muscle area and the width of the sac at the sac's end did not differ significantly. Overall there is minimal phenotypic change observed in the alphaERKO mouse compared to wild-type at the early developmental stages investigated. However, at postnatal day 7, there is a difference in the width of the cremasteric sac tip. This suggests that the effect of ERalpha, and thus signaling on the developing gubernaculum, occurs late in development. Alternatively, an action from the recently discovered ERbeta may be involved. Exploration of a betaERKO and the double knock-out alphaERKO/betaERKO mouse should be informative in evaluating the effect of endogenous estrogens in gubernacular development.

Gastrointestinal transit and anorectal manometry in children with colonic substance P deficiency

BACKGROUND AND AIMS

Severe intractable constipation in children may be associated with a reduction of substance P (SP)- containing fibers in colonic circular muscle. The aim of this study was to characterize gastrointestinal transit (GIT), anorectal manometry (ARM) and electromyographic (EMG) changes in these children.

METHODS

Seromuscular laparoscopic biopsies of the colon were obtained from 35 children with severe constipation. Immunofluorescent staining for SP and vasoactive intestinal peptide (VIP) were then performed on these specimens. The cohort of patients studied included a SP-deficient group (SPD, n = 25) who had reduced numbers of SP-immunoreactive nerve fibers. The other group consisted of patients with normal staining for both SP and VIP (SPN, n = 10). Gastrointestinal transit studies (gastric emptying, orocecal and colonic transit) suitable for analysis were available for 17 patients (SPD, n = 9 and SPN, n = 8). The colon was divided into segments and radioactivity counts in each segment were expressed as a percentage of the total colonic count at each time point (6, 24, 32 and 48 h). The geometric center (GC), ARM, EMG, clinical and demographic data characteristics of both groups of patients were compared.

RESULTS

There were no differences in demographic data, gastric emptying, orocecal transit or geometric center of transit in the colon between the two patient groups. The ARM and EMG studies suggested that the SPN group have a higher mean threshold volume of balloon distension required to initiate a rectoanal inhibitory reflex, and a higher incidence of anismus; however, this did not reach statistical significance.

CONCLUSIONS

These data suggest a trend that the SPN patients have a greater problem with obstructive defecation and abnormal rectal sensation than those with SPD. We were unable to confirm any defect in colonic transit in the SPD patients compared with the SPN group.

Enlargement of the processus vaginalis during testicular descent in rats

The role of the processus vaginalis (PV) during inguinoscrotal testicular descent remains controversial. Some authors propose passive dragging of the PV by the migrating testis, while others suggest active elongation. In addition, the exact site of growth is unknown. Our aim was to determine whether the PV actively proliferates at its tip or stretches passively during the inguinoscrotal phase of descent in the rat. Gubernacula were removed from Sprague-Dawley (SD) rats and congenitally-cryptorchid TS mutants. Animals (at days 3, 7, 10, and 11) were treated with bromo-uridine deoxyribose (BUdR) 2 h before death. BUdR incorporation into newly-synthesised DNA served as a marker for cell division. The gubernacula were processed for haematoxylin and eosin and immunoperoxidase staining. Three sites were examined: (1) the tip of the PV on either side of the gubernacular bulb; (2) the proximal gubernacular cord; and (3) the proximal parietal PV. At each site, 50 adjacent cells were counted and the number of positive cells recorded. The highest BUdR labelling in SD rats was at the tip (site 1) on day 3 (17/50) compared with sites 2 (11/50) and 3 (9/50) (P < 0.05). Labelling decreased by 7 and 11 days to similar levels in all three sites. In TS rats, labelling rates were lower at day 3 and were highest at the tip at day 11. These results suggest active growth of the caudal tip of the PV during testicular descent. In normal rats, the growth rate slows as the testis approaches the scrotum. By contrast, in TS rats growth continued longer. We propose that the PV elongates actively from the tip to allow the intraperitoneal testis to leave the abdomen in a special peritoneal diverticulum.

Leydig insulin-like hormone, gubernacular development and testicular descent

PURPOSE

Testicular descent is controlled by 2 morphological and hormonal steps. Transabdominal testicular descent is mediated by gubernacular swelling and regression of the cranial suspensory ligament. Müllerian inhibiting substance (MIS) has been proposed to stimulate the swelling but this remains controversial. Recently, a mouse mutant for Leydig insulin-like hormone (Insl3) was found to have undescended testis and deficient gubernaculum. We examine the testicular position of Insl3 mutant mice and the development of gubernacula.

MATERIALS AND METHODS

Mice with Insl3 homozygotes (-/-), heterozygotes (+/-) and wild-types (+/+) were examined at embryonic day 16.5 and birth. Macroscopic dissections and measurements of the testicular position, as well as microscopic analysis (hematoxylin and eosin, and Masson's trichrome) were performed.

RESULTS

Of the mice 11 Insl3 homozygote males had significantly impaired testicular descent at embryonic day 16.5 and birth (p <0.01), and the cord was thin and elongated, while 14 heterozygotes and 7 wild-types had normal testicular descent. Microscopically, the gubernaculum of Insl3 homozygotes was small with some muscle development but no central core of mesenchyme at embryonic day 16.5. On the other hand, heterozygotes and wild-types had normal gubernacular development with a swelling reaction.

CONCLUSIONS

Insl3 mutants show feminized gubernaculum with deficient mesenchymal core. Insl3 appears to have some role in the gubernacular swelling reaction in mice.

Ontogeny of bladder agenesis in rats induced by adriamycin

OBJECTIVES

To determine the anatomical steps leading to bladder agenesis in rats prenatally exposed as fetuses on gestational days (GD) 6-9 to adriamycin.

MATERIALS AND METHODS

Timed-pregnant Sprague-Dawley rats were injected intraperitoneally with adriamycin at 2 mg/kg (n = 28) on GD 6-9 (vaginal plug = day 0). The control group (n = 21) received saline. Fetuses were harvested on GD 10, 11, 12, 13, 14, 15 and 16. Serial paraffin sections were prepared from a minimum of 10 experimental and five control fetuses at each gestational age, and stained with either trichrome or haematoxylin and eosin, and examined by light microscopy.

RESULTS

In the control group the urorectal septum first became visible and the mesonephric ducts apparently abutting the anterior cloaca on GD 12. The presumptive urinary bladder was clearly defined on GD 14. On GD 15, the common excretory ducts became incorporated into the newly formed urogenital sinus and the ureters opened into the bladder. In the treated animals, beginning on GD 11, the undivided cloaca was noticeably smaller and by GD 13-14, the vesical extension of the urogenital sinus was conspicuously absent. Instead, opposite ureters joined to drain directly into the proximal blind-ending urethra or the persistent distal urogenital sinus.

CONCLUSIONS

Prenatal exposure of rat fetuses to adriamycin resulted in primary agenesis rather than secondary resorption of the bladder. The ontogeny showed that the mechanism underpinning bladder development is unique and is under the influence of factors that can be targeted by adriamycin. Further work will elucidate the unique nature of bladder organogenesis and should have important applications in future research into artificial bladders.

Investigation of the intra-abdominal oesophagus and hiatus in fetal rats with oesophageal atresia and tracheo-oesophageal fistula

After surgical management of their oesophageal atresia (OA) and tracheo-oesophageal fistula (TOF), most patients exhibit evidence of gastro-oesophageal reflux (GOR) and many have oesophagitis. However, the aetiology of the GOR is still controversial. This study was undertaken to document whether there are congenital abnormalities in the intra-abdominal oesophagus and the hiatus in the fetal rat with OA and TOF following exposure to adriamycin (ADR). Time-pregnant rats were injected daily with either saline or 2 mg/kg ADR intraperitoneally on gestational days (GD) 6-9. The fetuses (n = 56) from 8 litters were harvested on GD 21 for examination. The length of the oesophagus between the diaphragmatic crura and the gastro-oesophageal junction (GOJ) and the sizes of the stomach and the oesophageal hiatus were measured under a dissecting microscope. The length of the oesophagus between the diaphragmatic crura and the GOJ in the ADR-treated fetuses (0.85 +/- 0.37 mm) was significantly shorter than in control fetuses (2.41 +/- 0.32 mm) (P < 0.0001). The size of the stomach in ADR-treated fetuses (5.30 +/- 1.01 mm) was significantly smaller than in the controls (8.07 +/- 0.49 mm) (P < 0.001). Moreover, the size of the oesophageal hiatus in ADR-treated fetuses (1.16 +/- 0.43 mm) was markedly larger than in the controls (0.32 +/- 0.1 mm) (P < 0.0001). These results showed that the congenital abnormalities in ADR-treated rat fetuses may account for the oesophageal functional disorders seen after surgical correction in patients who have OA and TOF.

Undescended testis is accompanied by calcitonin gene related peptide accumulation within the sensory nucleus of the genitofemoral nerve in trans-scrotal rats

PURPOSE

Recent data suggest that calcitonin gene related peptide (CGRP) released from the sensory branch of the genitofemoral nerve may regulate testicular descent. We studied the number of CGRP immunoreactive cells in the sensory nucleus of the genitofemoral nerve (L1 to L2 dorsal root ganglia) in cryptorchid trans-scrotal rats. Four-week-old trans-scrotal rats with unilateral undescended testis underwent bilateral genitofemoral nerve dissection and retrograde nerve labeling with the fluorescent dye 4,6-diamidino-2-phenylindole (DAPI). Animals were sacrificed 48 hours later and the L1 to L2 dorsal root ganglia were removed. Serial sections were obtained and double fluorescent labeled with antibody to CGRP. Retrograde labeled and CGRP immunoreactive cells were counted using an epi-fluorescent microscope. In the 6 male trans-scrotal rats evaluated we noted a mean plus or minus standard deviation of 1,272 +/- 98 retrograde labeled dorsal root ganglion cells ipsilateral to a fully descended testicle, including 98 +/- 34 that were also CGRP immunoreactive. On the side of the undescended testis there was a mean of 1,600 +/- 304 DAPI positive cells and 160 +/- 51 CGRP immunoreactive, DAPI labeled cells. The difference was significant (p <0.02). This study shows that in trans-scrotal rats the sensory nucleus of the genitofemoral nerve contains more CGRP immunoreactive cells ipsilateral to an undescended testis than on the contralateral side, highlighting the significance of CGRP supply through the sensory branch of the genitofemoral nerve for testicular descent.

Rectal mucosal biopsy compared with laparoscopic seromuscular biopsy in the diagnosis of intestinal neuronal dysplasia in children with slow-transit constipation

BACKGROUND/PURPOSE

Intestinal neuronal dysplasia (IND) as a cause for severe chronic constipation remains controversial. The aim of this study is to examine the correlation between a deficiency of substance P (SP) immunoreactive nerve fibers in the colon and enzyme histochemistry of rectal biopsies in children with slow-transit constipation.

METHODS

Fifty children with intractable constipation have been assessed by rectal biopsies examined with histochemical staining for lactate dehydrogenase, and 32 children among those 50 have been studied by laparoscopic seromuscular biopsy of the colon labelled with antibodies to SP using immunofluorescence methods.

RESULTS

Four children have evidence of IND. Fifteen children, including all 4 IND cases, showed a deficiency of SP immunoreactivity. There is a significant correlation between giant ganglia and SP deficiency (P <.01).

CONCLUSION

This study is attempting to propose that a deficiency of SP immunoreactivity in colonic circular muscle nerves may be used as a histologic marker for slow-transit constipation and that IND may be a small subset of patients with SP deficiency.

Patterns of radial dysmorphology with the VACTERL association in the adriamycin-exposed prenatal rat

The VACTERL association is an acronym for a constellation of abnormalities affecting the spinal column, anus, heart, trachea, esophagus, kidneys, and limbs that are seen in newborns. It has been shown that prenatal rats exposed to Adriamycin demonstrate a similar series of anomalies. It is the aim of this study to characterize the spectrum of limb anomalies in this model. Female Sprague-Dawley rats (N = 18; 14 experimental and 4 control) were used. After mating, pregnant animals received intraperitoneal injections of Adriamycin (2 mg per kilogram) on days 6, 7, 8, and 9 of gestation. Fetuses were recovered on day 21 of gestation. Ten experimental litters (42 fetuses) and two control litters (18 fetuses) underwent skeletal staining with Alizarin Red S stain. Four experimental litters (N = 18) and two control litters (N = 17) underwent histological study including staining for vascular and neural structures. Upper limb anomalies were found in 45% of the experimental animals, all including either hypoplasia or bending of the radius. The ulna was involved in 37% of the affected limbs. There were no isolated ulnar deformities. There were no histological differences noted. The spectrum of upper limb anomalies seen in the Adriamycin-exposed prenatal rat closely approximates, in incidence and morphology, the upper limb deformities seen with the VACTERL association in children. It is a reliable model for use in additional studies of the embryological mechanism by which these defects arise.