Hormonal regulation of testicular descent: experimental and clinical observations

Male animal sterilization: history, current practices, and potential methods for replacing castration

Sterilization and castration have been synonyms for thousands of years. Making an animal sterile meant to render them incapable of producing offspring. Castration or the physical removal of the testes was discovered to be the most simple but reliable method for managing reproduction and sexual behavior in the male. Today, there continues to be global utilization of castration in domestic animals. More than six hundred million pigs are castrated every year, and surgical removal of testes in dogs and cats is a routine practice in veterinary medicine. However, modern biological research has extended the meaning of sterilization to include methods that spare testis removal and involve a variety of options, from chemical castration and immunocastration to various methods of vasectomy. This review begins with the history of sterilization, showing a direct link between its practice in man and animals. Then, it traces the evolution of concepts for inducing sterility, where research has overlapped with basic studies of reproductive hormones and the discovery of testicular toxicants, some of which serve as sterilizing agents in rodent pests. Finally, the most recent efforts to use the immune system and gene editing to block hormonal stimulation of testis function are discussed. As we respond to the crisis of animal overpopulation and strive for better animal welfare, these novel methods provide optimism for replacing surgical castration in some species.

Concepts and Updates in the Evaluation and Diagnosis of Common Disorders of Sexual Development

Our understanding of disorders of sexual differentiation (DSD) has evolved from aberrations of human genital development to a broad group of complex disorders of etiological and functional significance. The unique challenge of DSD conditions is that they create a cause for significant angst and concern for both parents and physician, as they frequently lead to questions with regards to gender assignment, surgically corrective options, long-term outlook regarding gender identity, and reproductive potential. To further add to the burden, many patients who present with genital abnormalities do not have a clear explanation as to the underlying basis of their disorder. This review looks at DSD from a pediatric urology point of view with emphasis on evaluation, diagnosis, and algorithm for work-up. We also discuss novel genetic analysis techniques and their value in diagnosis. Overall, this is an all-encompassing review on a diagnostic approach to DSD, with inclusion of recent developments and controversies, which will benefit urologists and other physicians alike.

Endocrine and morphological perspectives in testicular descent

Before sexual differentiation occurs at seven weeks, the urological ridges develop in the embryo. These contain the primitive gonads, the mesonephros (embryonic kidneys) and the paired Wolffian (mesonephric) ducts, along with the Müllerian (paramesonephric) ducts. The fundamental mechanism of fetal sexual development was elucidated by Alfred Jost and is determined by the development of the gonad: where testes form in response to the testis-determining gene, and the male testicular hormones cause development of the male phenotype. If ovaries develop or the gonads are absent, female secondary sex characteristics are produced. Recently, the cloning of the putative human testis-determining gene on the Y-chromosome was reported. Assuming this is the true controller of testicular development, an understanding of the initiation of sexual differentiation at the genetic level should emerge in the near future. Of great importance will be the isolation of the testis-determining gene product and identification of other genes that it regulates.

Influence for testicular development and histological peculiarity in the testes of flutamide-induced cryptorchid rat model

OBJECTIVES

To investigate influence for the testicular development and to assess the usefulness as an animal model, cryptorchid rats were induced by exposure to flutamide during the fetal period and their testes examined histologically.

METHODS

Flutamide was injected into the abdomen of pregnant rats for 7 days from the 14th to 20th day of gestation. The male offspring in which cryptorchidism was observed at 28 days after birth were defined as the model rats. They were divided into four groups by dosage of flutamide (2.5 mg, 5 mg, 7.5 mg, 15 mg per day), and their testicular weight, spermatogenesis (modified Johnsen score), and germ cell apoptosis were examined histochemically at 10 weeks after birth.

RESULTS

The incidence of cryptorchidism including both unilateral and bilateral in the 2.5, 5, 7.5 and 15-mg flutamide groups was 58.3%, 81.9%, 93.6% and 91.0%, respectively. In the model rats, the undescended testes were located at the caudal end of the abdominal cavity, and these testes weighed less than the contra-descended testes in each group. Histologically, apoptotic cells were markedly increased, the seminiferous tubules were degenerated and disturbance of spermatid differentiation was observed in the undescended testes compared with the normal or contra-lateral descended testes.

CONCLUSIONS

We found out that the incidence of undescended testes increased in a flutamide dose-dependent manner. The findings of histological examination were independent of the administrated dose of flutamide and it is suggested that exposure of the testes to abdominal temperature causes spermatogenic arrest with germ cell apoptosis. The present animal model indicates high incidence of above 90%, has no surgical stress and dose not require special techniques. We believe that the present model is a useful tool for the understanding of pathogenesis and treatment of cryptorchidism and further biological research into spermatogenesis.

Management of neonates with large abdominal wall defects and undescended testis

OBJECTIVES

To assess, in a retrospective study, the outcome of different treatment modalities in newborns with undescended testes secondary to large abdominal wall or diaphragmatic defects. Large abdominal and diaphragmatic defects are known to be associated with cryptorchidism, yet the reported incidence varies widely.

METHODS

A total of 112 neonates with large abdominal wall or diaphragmatic defects were treated from 1981 to 2005. Of the 55 male patients in this series, 9 (16.4%) presented with abdominal testes and 4 had an extra-abdominal testis (7.3%).

RESULTS

The 2 patients undergoing primary orchiopexy had testes of normal size and in the normal position at last follow-up. In one of these patients in whom the testis was brought down to the internal inguinal ring, spontaneous descent occurred and the testis on the affected side was normal. The other patient required additional surgery and had an atrophic testis at last follow-up. In 1 patient with severe concomitant malformations, primary orchiectomy was performed. The 4 patients who did not receive initial treatment all lost their testes owing to atrophy.

CONCLUSIONS

The results of the present study have indicated that primary orchiopexy should be attempted in all cases of abdominal wall defects associated with abdominal cryptorchid testes because it yields better testicular salvage rates. In cases in which the spermatic cord is not long enough to place the testis into the scrotum, mobilization and fixation at the lowest site possible resulted in better outcomes than leaving the testis in the abdomen.

New facets of androgen replacement therapy during childhood and adolescence

The goals of androgen therapy for adolescents are to promote linear growth and secondary sexual characteristics, at the same time as permitting the normal accrual of muscle mass and bone mineral content. Secondary goals are mainly in the psychosocial sphere, in which pubertally delayed boys feel that they look too young, are not considered a 'peer' in their age group and have difficulty competing in athletic endeavours. These goals are irrespective of the causes of delayed pubertal development: constitutional delay of growth and puberty (CDGP), a transient but very common form of pubertal delay and, much less commonly, primary or secondary permanent hypogonadism. Not all boys with CDGP require testosterone therapy, but those that come to a referral practice are likely candidates, as the watchful waiting period has finished. Although a range of androgen preparations is available for adults (injectable, oral, implantable and cutaneous patches and gels), most are drug delivery devices that are appropriate for full adult androgen replacement. These doses are too large for the induction of puberty. Therefore, at present, the injectable form is the only one that is easily adaptable for the increasing amounts of androgen necessary for the various stages of pubertal development. All preparations deliver testosterone that is readily converted to dihydrotestosterone by 5-alpha reductase. The author's practice is to begin with injecting 50-75 mg of one of the long-acting esters (enanthate or cypionate) per month, and gradually escalate to 100-150 mg/month, before changing to twice monthly dosage. As most adolescents have delayed puberty, the therapy is needed for 6-18 months before the hypothalamic-pituitary-gonadal axis functions at the late adolescent/adult level in those with CDGP. Those with permanent hypogonadism will require lifelong therapy. Once adequate virilisation is induced, and virtually full adult height is reached, any of the therapies noted above can be used in those permanently hypogonadal, whether primarily or secondarily.

New insights into the regulation of mammalian sex determination and male sex differentiation

In mammals, sex development is a genetically and hormonally controlled process that begins with the establishment of chromosomal or genetic sex (XY or XX) at conception. At approximately 6 to 7 weeks of human gestation or embryonic day e11.5 in the mouse, expression of the Y chromosome-linked sex determining gene called SRY (described in detail in this chapter) then initiates gonadal differentiation, which is the formation of either a testis (male) or an ovary (female). Male sex differentiation (development of internal and external reproductive organs and acquisition of male secondary sex characteristics) is then controlled by three principal hormones produced by the testis: Mullerian inhibiting substance (MIS) or anti-Mullerian hormone (AMH), testosterone, and insulin-like factor 3 (INSL3). In the absence of these critical testicular hormones, female sex differentiation ensues. This sequential, three-step process of mammalian sex development is also known as the Jost paradigm. With the advent of modern biotechnologies over the past decade, such as transgenics, array-based gene profiling, and proteomics, the field of mammalian sex determination has witnessed a remarkable boost in the understanding of the genetics and complex molecular mechanisms that regulate this fundamental biological event. Consequently, a number of excellent reviews have been devoted to this topic. The purpose of the present chapter is to provide an overview of selected aspects of mammalian sex determination and differentiation with an emphasis on studies that have marked this field of study.

Expression of estrogen receptor ESR1 and its 46-kDa variant in the gubernaculum testis

Testicular descent corresponds to migration of the testis from the abdominal cavity to the scrotum and is essential for proper functioning of the testis. Recent advances in the characterization of estrogen receptor (ESR) subtypes and isoforms in various tissues prompted us to study ESRs within the gubernaculum testis, a structure involved in testicular descent. In the rat gubernaculum, we searched for ESR alpha (Esr1) and beta (Esr2) and for the androgen receptor (Ar), androgens being known to regulate testicular descent. Reverse transcription-polymerase chain reaction (RT-PCR) revealed that Esr1, Esr2, and Ar mRNAs were all expressed in the gubernaculum. Using PEETA (Primer extension, Electrophoresis, Elution, Tailing, and Amplification), we established that all Esr1 leader exons, previously identified in other organs, such as the uterus and pituitary, were transcribed in the gubernaculum, with the major form being O/B. The RNA protection assays, RT-PCR, and Western blot experiments revealed that isoform-specific mRNA transcripts generated by alternative splicing of the C-leader sequence on coding exons 1 and 2 of the Esr1 gene gave the 46- and 66-kDa ESR1 proteins. The ESR1 and AR proteins were found to colocalize in the parenchymal cells of the gubernaculum early in development, whereas AR also was strongly expressed in the muscular cells, both during fetal and postnatal life. The ESR2 protein was weakly expressed, principally in the muscular cells, but only once testicular descent had occurred. The levels of the 46-kDa ESR1 variant (ER46) exceeded those of the 66-kDa ESR1 form (ER66) at periods when the gubernaculum developed. Conversely, the 66-kDa form appears to predominate clearly when the gubernaculum growth was low or completed. The possible role of estrogens on the modulation of the androgen-dependent growth of the gubernaculum and, more widely, on testicular descent is discussed.

Testicular descent and cryptorchidism: the state of the art in 2004

The understanding of testicular descent has changed much in the 20 years since the authors' laboratory began studying the mechanism. The process is now known to occur in 2 steps with different anatomy and hormonal regulation but with many still unresolved controversies. Recent advances include the recognition of acquired cryptorchidism of critical early postnatal germ cell development and the recommendation for surgery at 6 months of age. The authors still await long-term outcome studies.

Neonatal exposure to di(n-butyl) phthalate (DBP) alters male reproductive-tract development

The purpose of this study was to evaluate male reproductive-organ development in early postnatal male rats following neonatal exposure to di(n-butyl) phthalate (DBP) and identify a mechanism of action. Neonatal male rats were injected subcutaneously from d 5 to 14 after birth with corn oil (control) and DBP (5, 10, or 20 mg/animal). Animals were killed at postnatal day (PND) 31 and PND 42, respectively, and testes, epididymis, seminal vesicles, ventral prostate, levator ani plus bulbocavernosus muscles (LABC), and Cowper's glands were weighed. In addition, the expressions of androgen receptor (AR), estrogen receptors (ERs), and steroidogenic factor-1 (SF-1) were also examined in the testes. Total body weights gains were significantly reduced at PND 29-31, but gradually recovered on PND 42. However, DBP (20 mg/animal) significantly reduced the weights of testes and accessory sex organs (seminal vesicles, LABC, and Cowper's glands), but not of the epididymis. These adverse effects persisted through puberty at PND 42. Serum testosterone levels did not show any significant changes in the control and DBP treatment groups. Histomorphological examination showed mild diffuse Leydig-cell hyperplasia in the interstitium of severely affected tubules on PND 31. Only a few multinuclear germ cells were observed. DBP (20 mg/animal) significantly decreased the expression of AR, whereas ER expression and SF-1 expression were increased in a dose-dependent manner on PND 31 in the rat testes. On PND 42, DBP (20 mg/animal) significantly inhibited ER expression in the testes, but not AR, ER, and SF-1. These results demonstrate that neonatal exposure to DBP produces permanent changes in the endocrine system and leads to abnormal male reproductive-tract development until puberty. Thus our data suggest that DBP is likely to exert its antiandrogenic actions through disruption of AR or ER expression during the early neonatal stage.

Congenital absence of the testis in human fetuses and in cryptorchid patients

BACKGROUND

The aim of the present study is to make a comparative study in human fetuses and in patients with cryptorchidism, analyzing the incidence of a number anomalies of the testes for both populations.

METHODS

We studied 326 testes from 163 human fetuses ranging in age from 10 to 35 weeks postconception (WPC) and 133 testes from 101 cryptorchid patients aged from 1 to 15 years old (mean, 6.4 years). The Fisher's exact test was used for comparison.

RESULTS

Among 326 fetal testes, 224 (68.7%) were abdominal, 45 (13.8%) were inguinal and 55 (16.8%) were scrotal. In one fetus at 23 WPC, both testes (0.6%) were absent. Of the 133 cryptorchid testes, 17 (12.78%) were abdominal, 92 (69.1%) were inguinal and 24 (18%) were high scrotal. Of the 17 abdominal testes, three (17.6%) were atrophic and two were vanished (11.7%). Of the 92 inguinal testes, one (1.08%) was vanished. Twenty-eight (21%) of the cryptorchid testes were impalpable and among these, 17 were located in the abdomen (60.7%) and 11 (38.2%) in the inguinal region (internal ring).

CONCLUSIONS

Testicular agenesis is a very rare anomaly, both in fetuses and patients with cryptorchidism.

Molecular and genetic regulation of testis descent and external genitalia development

Testicular descent as a prerequisite for the production of mature spermatozoa and normal external genitalia morphogenesis, and therefore facilitating copulation and internal fertilization, are essential developmental steps in reproduction of vertebrate species. Cryptorchidism, the failure of testis descent, and feminization of external genitalia in the male, usually in the form of hypospadias, in which the opening of the urethra occurs along the ventral aspect of the penis, are the most frequent pediatric complications. Thus, elucidating the molecular mechanisms involved in the regulation of testis descent and the formation of external genitalia merits a special focus. Natural and transgenic rodent models have demonstrated both morphogenic processes to be under the control of a plethora of genetic factors with complex time-, space-, and dose-restricted expression pattern. The review elucidates the molecular mechanisms involved in the regulation of testis descent and the formation of external genitalia and, wherever possible, assesses the differences between these rodent animal models and other mammalian species, including human.

Androgen receptor and calcitonin gene-related peptide in neurons of the genitofemoral nerve during testicular descent induced with human chorionic gonadotropin

BACKGROUND

Low levels of circulating testosterone during testis descent cause cryptorchidism in humans and rats. Treatment with human chorionic gonadotrophin (hCG) induces testis descent by stimulating production of testosterone (T). Neurons of genitofemoral nerve (GFN), which innervate testicular gubernaculum, may play a role in testis descent.

METHODS

In the current study, putative correlations were made between T and GFN motor and sensory neuron activity during inguinoscrotal testis descent. Cryptorchidism was provoked in prepuberal rats with estradiol. Rats with testicular descent induced with hCG and cryptorchid controls were used. Cells of spinal cord and dorsal root ganglia were labeled by retrograde staining with fast-blue. Expression of androgen receptor (AR) and calcitonin gene-related peptide (CGRP) were detected with indirect immunofluorescence.

RESULTS

Neurons labeled with fast-blue were found in the center of motor horn and dorsal root ganglia at levels L1 and L2. While number of motor neurons expressing AR was significantly higher in the group treated with hCG, number expressing CGRP was higher in controls. In dorsal root ganglion, number of cells immunostained with CGRP antibody was similar in both groups but AR was not detected.

CONCLUSIONS

Present results support the hypothesis that motor nucleus of the GFN is a direct target of testosterone and that regulation of CGRP in sensory nucleus may be involved in testicular descent.

Disturbed pituitary-testicular axis inhibits testicular descent in the prenatal rat

OBJECTIVE

To investigate whether prenatal stress affects the pituitary-testicular axis in relation to testicular descent in rat fetuses, as maternal stress can alter the plasma testosterone concentration and inhibit testicular descent in male rat fetuses.

MATERIALS AND METHODS

Pregnant rats were divided into two groups and kept in reverse light-dark cycles, with lights-off at 08.00 hours and on at 20.00 hours. In group 1, 15 pregnant females were placed three times daily for 60 min each session in plastic rat-holders (13 x 6 x 8 cm) illuminated by two 150-W flood lights during the dark phase, from day 14 to 18 of gestation. In group 2, 10 pregnant females were not handled and thus were used as controls. At 19 days of gestation, five pregnant rats had a Caesarean section in each group, and both testes and the pituitary gland were removed from male fetuses at 10.00-11.00 hours. The tissue homogenates were analysed for testicular testosterone and pituitary luteinizing hormone (LH) by a radioimmunoassay. Thereafter, at 21 and 30 days of age, testicular descent was assessed in the remaining male offspring. Student's t- and the chi-square test were used to assess the results.

RESULTS

The mean (sd) concentration of fetal testicular testosterone was significantly lower in group 1, at 312.9 (26.2) pg/mg, than in group 2, at 532.5 (18.2) pg/mg (P < 0.05); that of pituitary LH was also significantly lower in group 1, at 130.6 (22.7) and 295.6 (35.2) pg/mg, respectively (P < 0.05). The completion rate of testicular descent was 14% in group 1 (36 male rats) and 64% in group 2 (28 male rats) at 21 days old, and thereafter they were 81% and 100%, respectively, at 30 days old (P < 0.05).

CONCLUSION

Maternal stress might inhibit the pituitary-testicular axis, thereby resulting in abnormal testicular descent in male fetuses.

Comparison of five different hormonal treatment protocols for children with cryptorchidism

OBJECTIVE

To compare the effects of medical therapy on boys with cryptorchidism, a prospective study was carried out in five groups of patients over a 30-month period.

MATERIAL AND METHODS

A total of 439 boys with undescended testicles were enrolled; their ages ranged between 6 months and 13 years (median 4.2 years). Of these, 327 had true unilateral and 112 bilateral undescended testicles. In 115 patients surgery was performed directly either because the condition was associated with inguinal hernia or because the child had undergone previous inguinal surgery; hormonal treatment was attempted in the remaining 324 patients. Human chorionic gonadotrophin (hCG) was administered to 113 patients (34.8%), luteinizing hormone-releasing hormone (LH-RH) to 85 (26.2%), a combination of LH-RH and hCG to 64 (19.7%), human menopausal gonadotrophin (hMG) to 35 (10.8%) and a combination of hMG and hCG to 27 (8.3%).

RESULTS

Overall, testicular descent was achieved in 27.7% (90/324) of patients: specifically, in 38.2% (36/94) of boys with bilateral undescended testicles (both testes in 22/36, one testis only in 14/36) but in only 23.4% (54/230) of those with unilateral undescended testicles (p = 0.007). The correlation between the type of therapy and testicular descent can be summarized as follows: hCG, 39/113 (34.5%); LH-RH, 25/85 (29.4%); hCG+LH-RH, 19/64 (29.6%); hCG+hMG, 7/27 (25.9%); hMG alone, 0/35 (0%).

CONCLUSIONS

In our experience, pharmacological treatment seems to yield better results in cases of bilateral than unilateral cryptorchidism. hCG seems to be equally effective as LH-RH for the treatment of cryptorchidism in approximately 30% of cases; the combination of these two drugs does not seems to increase the success rate. The use of hMG alone is ineffective. We believe that hormonal treatment can lead to acceptable results in boys with cryptorchidism, without relevant adverse effects.

Sonographic detection of undescended testes in the third trimester

OBJECTIVE

To assess the sonographic detection rate of fetal undescended testes among a low-risk population during the third trimester.

METHODS

A sonographic evaluation, which included biometric studies and a detailed examination of the fetal genitalia, was performed prospectively on 332 male fetuses of singleton pregnancies between 34 and 40 weeks' gestation. A qualified neonatologist examined the presence of the testes within the scrotum within 3 days after birth.

RESULTS

The scrotum was visible in 294 (89%) of the 332 fetuses who were examined. It was visible in all fetuses evaluated between 34 and 36 weeks' gestation. Nine cases of undescended testes were detected (3%). Of these, the diagnosis of 1 case, examined at 34 weeks' gestation, was revealed after birth to be false-positive. There were no false-negative results.

CONCLUSIONS

Sonographic examination during the late third trimester of pregnancy appears to allow accurate diagnosis of undescended testes prenatally. This early identification will alert the neonatologist of the possibility of cryptorchidism and will permit early postnatal identification and treatment.

Association of prenatal phenobarbital and phenytoin exposure with genital anomalies and menstrual disorders

BACKGROUND

Animal studies demonstrated that early exposure to phenobarbital decreases reproductive function. This study investigates whether prenatal exposure to these anticonvulsants affects human genital tract development.

METHODS

Genital anomalies at birth were studied retrospectively in 90 phenobarbital-exposed, 108 phenobarbital plus phenytoin-exposed, and 198 matched control infants. Of this group, 72 drug-exposed males, 75 drug-exposed females, and 147 matched control subjects participated in a follow-up and were interviewed at age 19-35. Differences between groups were tested by chi-square and t-tests.

RESULTS

A total of 15% of the phenobarbital-exposed boys versus 2.8% control boys had undescended testes at birth. More anticonvulsant-exposed (24%) than control males (11%) had received medical treatment for genital anomalies. Anticonvulsant-exposed females more often had irregularities in menstrual cycles (31% vs. 17%) and bleeding (15% vs. 3%) and reported more problems during pregnancy.

CONCLUSIONS

Prenatal exposure to anticonvulsants seems to induce minor genital anomalies and may affect reproductive function.

Is routine karyotyping necessary in the evaluation of hypospadias and cryptorchidism?

PURPOSE

The incidence of intersex states has been reported to be 27% to 100% in patients with hypospadias and cryptorchidism, and routinely determining karyotypes has been recommended. This incidence seems much higher than in our experience. We reviewed the records of patients with hypospadias and/or chordee plus cryptorchidism as well as those referred with ambiguous genitalia to determine whether these findings were associated with a high incidence of chromosomal abnormalities and whether they warrant routine karyotype screening.

MATERIALS AND METHODS

We reviewed the records of patients with undescended testis plus hypospadias and/or chordee, and those with ambiguous genitalia who presented between 1986 and 1999. Patients without karyotype determination, and those with iatrogenic cryptorchidism, retractile testes, congenital adrenal hyperplasia or female-appearing external genitalia were excluded from study. Meatus and testis locations at surgery, and associated Müllerian structures and medical conditions were documented. Fisher's exact test was done to determine statistical significance.

RESULTS

Of the 113 patients whose records matched study inclusion criteria only 48 had complete anatomical, karyotypic, pathological and radiographic information available. Eight patients (16.7%) had chromosomal abnormalities, including 2 (4.2%) with karyotypic intersex disorder and 6 (12.5%) with autosomal chromosomal abnormalities. There were persistent Müllerian structures in 2 patients (4.2%) with a normal 46 XY karyotype. As described by a staff pediatric urologist, 20 patients (41.7%) had ambiguous genitalia and 8 of the 48 (16.7%) had nonpalpable cryptorchidism. Ambiguous genitalia were associated with chromosomal abnormalities, in 4 of the 20 cases, including 2 karyotypic intersex cases. Only 3 patients with ambiguous genitalia had nonpalpable gonads and 1 with karyotypic intersex disorder had a nonpalpable gonad that involved the testicular elements only. The incidence of autosomal chromosomal abnormalities was not significant (2-tailed Fisher's exact test p <==0.05) and the incidence of karyotypic (autosomal or sex) abnormalities was not significant compared with hypospadias (p = 0.3), genital ambiguity (p = 0.7) or cryptorchidism (p = 0.69), including nonpalpable testis (p = 1). When patients had karyotypic abnormalities, they were more likely to have proximal hypospadias (57.2%), palpable cryptorchidism (62.5%) and ambiguous genitalia (50%).

CONCLUSIONS

Most patients who present for the evaluation of hypospadias, chordee and undescended testis have a normal karyotype. Routine karyotype investigation of all patients with hypospadias, chordee and cryptorchidism does not seem warranted. If karyotypic intersex abnormalities are identified, those patients are more likely to have ambiguous genitalia, especially those with perineal hypospadias and cryptorchidism.

Estrogen and spermatogenesis

Although it has been known for many years that estrogen administration has deleterious effects on male fertility, data from transgenic mice deficient in estrogen receptors or aromatase point to an essential physiological role for estrogen in male fertility. This review summarizes the current knowledge on the localization of estrogen receptors and aromatase in the testis in an effort to understand the likely sites of estrogen action. The review also discusses the many studies that have used models employing the administration of estrogenic substances to show that male fertility is responsive to estrogen, thus providing a mechanism by which inappropriate exposure to estrogenic substances may cause adverse effects on spermatogenesis and male fertility. The reproductive phenotypes of mice deficient in estrogen receptors alpha and/or beta and aromatase are also compared to evaluate the physiological role of estrogen in male fertility. The review focuses on the effects of estrogen administration or deprivation, primarily in rodents, on the hypothalamo-pituitary-testis axis, testicular function (including Leydig cell, Sertoli cell, and germ cell development and function), and in the development and function of the efferent ductules and epididymis. The requirement for estrogen in normal male sexual behavior is also reviewed, along with the somewhat limited data on the fertility of men who lack either the capacity to produce or respond to estrogen. This review highlights the ability of exogenous estrogen exposure to perturb spermatogenesis and male fertility, as well as the emerging physiological role of estrogens in male fertility, suggesting that, in this local context, estrogenic substances should also be considered "male hormones."

Proximal insertion of gubernaculum testis in normal human fetuses and in boys with cryptorchidism

PURPOSE

We determine how the proximal gubernaculum testis is attached to the testis and epididymis in human fetuses, and compare these data with findings in boys who had undergone surgery for cryptorchidism.

MATERIALS AND METHODS

We analyzed 280 testes and epididymides with the gubernacula of 140 well preserved, fresh human fetuses ranging from 10 to 35 weeks after conception with no detectable congenital malformations and 36 undescended testes of 28 boys 2 to 15 years old (mean age 6.8) who had undergone surgery for cryptorchidism. In both groups the different conformations of the relationship among the proximal gubernaculum, testis and epididymis were classified according to a system used for patients with cryptorchidism. In group A the gubernaculum is attached to the testis and epididymis, in group B the gubernaculum is attached only to the testis with a tail disjunction epididymal anomaly, in group C the gubernaculum is attached only to the testis with total disjunction of the epididymis, in group D the gubernaculum is attached only to the epididymal tail and in group E there are no attachments among gubernaculum, testis and epididymis.

RESULTS

Of the 280 fetal testes studied 194 (69.2%) were in the abdomen, 38 (13. 57%) in the inguinal canal and 48 (17.14%) in the scrotum. There were 277 cases (98.9%) in group A and 3 (1.1%) in group B. Of the 36 undescended testes analyzed 2 (5.6%) were abdominal and 34 (94.4%) were inguinal. There were 26 cases (72.2%) in group A, 8 (22.2%) in group B and 2 in group D.

CONCLUSIONS

In fetuses without congenital malformations or epididymal alterations, such as tail disjunction or elongated epididymis, the proximal portion of the gubernaculum was attached to the testis and epididymis in all cases. In undescended testes there was an increased incidence of paratesticular structure malformations accompanied by gubernacular attachment anomalies compared to the testes in normal fetuses.

Time-specific effects of mono-n-butyl phthalate on the transabdominal descent of the testis in rat fetuses

OBJECTIVE

To determine the time-specific effects of mono-n-butyl phthalate (MBP) on the transabdominal migration of the testis in fetal rats. Materials and methods Three groups of pregnant rats were administered MBP by stomach-tube feeding when the fetus was at 7-10 days of gestation in group 1, 11-14 days in group 2, and 15-18 days in group 3; controls (group 4) were given vehicle only from 7-18 days. At 20 days of gestation the fetuses were obtained by Caesarean section, and the position of the testes, the development of the gubernaculum, cranial suspensory ligament and the epididymis were examined.

RESULTS

The timed intervals of MBP administration showed that the maximum inhibition of transabdominal testicular descent was at 15-18 days of gestation. There was an elongated gubernaculum and hypertrophic cranial suspensory ligament in the MBP-treated rat fetuses. Furthermore, the epididymis showed a few small ducti deferentia, although there were no remarkable changes in either the Sertoli and Leydig cells in these testes. The mean (SEM) content of testicular testosterone was significantly less (P < 0.001) in the MBP-treated rats, at 50.9 (3.8) pg/testis, than in the controls, at 676 (33.3) pg/testis.

CONCLUSIONS

These findings indicate that a brief exposure to MBP during fetal development can inhibit the transabdominal migration of the testis and reduce testosterone content in rats, although the relationship between migration and the testicular testosterone content remains unknown.

Management of undescended testis

The term cryptorchidism indicates a testis, which has failed to descend to the scrotum and is located at any point along the normal path of descent or at an ectopic site. Hormones play a pivotal role in testicular descent except during the migration to the level of internal inguinal ring. Cryptorchidism is present in about 4.5% of newborns with a higher incidence in preterms. The incidence decreases to 1.2% by the first year. It is classified as palpable and impalpable. The most common site of an ectopic testis is superficial inguinal pouch. Retractile testis is often bilateral and most common in boys between 5 and 6 years of age. Hypospadias and inguinal hernias are the most common associated anomalies seen with undescended testis. A thorough clinical examination helps in arriving at the etiology. A short hCG stimulation test helps to exclude anorchia. Different imaging techniques are of little help in diagnosis and require the help of an experienced radiologist. Laparoscopy has an important role in the diagnosis and management of undescended testis. The common complications include torsion and atrophy of testis. Infertility is seen in about 40% of unilateral and 70% of bilateral cryptorchidism. Undescended testis is 20 to 40 times more likely to undergo malignant transformation than normal testis. Both hCG and GnRH have been used with limited success in these children. All boys with cryptorchidism should be referred to a pediatric surgeon before 2 years of age. These children should be followed up every year after surgery to identify testicular tumors.

Reproductive effects of endosulfan on male offspring of rats exposed during pregnancy and lactation

1. The reproductive effects of endosulfan on the male offspring of rats were examined. Dams were treated orally with 0, 1.5 or 3.0 mg endosulfan/kg from day 15 of pregnancy to postnatal day (PND) 21 of lactation. The male offspring rats were investigated at PND 65 or 140, corresponding to the pubertal and adulthood stage of development. 2. The dose of 3.0 mg endosulfan/kg induced a decrease in maternal body weight during pregnancy, but litter size and mean birth weight were not affected. Similarly, the age at testis descent and preputial separation was not affected on the male offspring. 3. The daily sperm production (x10(6)) was permanently decreased in the highest dose group when investigated at puberty and at adulthood. At the lowest dose, however, the daily sperm production was significantly reduced only at puberty. 4. Histologically, the percentage of seminiferous tubules showing complete spermatogenesis was significantly decreased at puberty. This finding may explain the decrease in daily sperm production observed in the endosulfan-exposed male rats. 5. The results of this study show that low doses of endosulfan have no apparent effect on developmental landmarks or on the weight of reproductive and accessory sex organ. Daily sperm production was the most susceptible endpoint in the male offspring exposed to endosulfan during pregnancy and lactation. To further understand the reproductive effects of endosulfan on male rat offspring, additional reproductive and toxicokinetic studies should be carried out to determine the extent of endosulfan exposure in male rat offspring in utero and during lactation.

The potential roles of estrogens in regulating Leydig cell development and function: a review

It is generally agreed that estrogens, principally estradiol-17beta, are synthesized by and act in the testis of mammals, including humans. The site of estradiol synthesis in the testis is generally believed to begin in the Sertoli cell and switch to the Leydig cell during neonatal development where a gonadotropin-regulated aromatase is present. Numerous studies suggest that the primary target cell of estradiol in the testis at all ages is the Leydig cell. In fact, the Leydig cell is known to possess an estrogen receptor that binds estradiol in the classic manner. The mechanism of estradiol action and the role of its receptor in the testis, however, remain unresolved. In Leydig cells, estradiol appears to induce several alterations that are dependent in large part on the developmental stage of the Leydig cell. In the fetal and neonatal testes, estradiol appears to block the ontogenic development of Leydig cells from precursor cells. There is also evidence that estradiol similarly blocks the regeneration of Leydig cells in the testis of mature, ethane dimethylsulfonate-treated animals. Evidence indicates that the precursor cell possesses high levels of estrogen receptors relative to that of the Leydig cell. It is postulated that estradiol is a paracrine factor involved in regulating the interstitial population of Leydig cells. Evidence also indicates that estradiol acts directly in the mature testis to block androgen production. It appears to do so by inhibiting the activities of several steroidogenic enzymes involved in testosterone synthesis. Although the more conventional receptor-mediated mode of action is feasible, several studies have suggested that this action might entail direct competitive inhibition of key steroidogenic enzymes by estradiol. In summary, the net biologic effect of estradiol in the testis appears to be inhibition of androgen production, either by limiting development and growth of the Leydig cell population or through direct action in the Leydig cell.

Endocrinological parameters in experimental unilateral undescended testis

It is a common clinical practice to estimate FSH, LH and testosterone levels in patients with unilateral undescended testis (U/L UDT) as a prognostic pointer to fertility potential. Is this practice correct? To ascertain this aspect, new born rats were operated to create experimental U/L UDT by gubernaculectomy and anchoring the gubernaculum to anterior abdominal wall. Fertility and hormone levels were evaluated later in adult life. Though fertility of rats with U/L UDT was significantly less (p < 0.01) than the controls, no significant alterations were found in the levels of serum testosterone, FSH and LH. Even though variations in the hormone levels may be responsible, to a certain extent, for the decrease in fertility potential in U/L UDT, estimation of sex hormone levels in U/L UDT is not a sensitive indicator of fertility potential. U/L UDT may additionally be affecting fertility through non-endocrinological mechanisms.

Pediatric testicular problems

Testicular problems in children may be both congenital and acquired. These problems are often difficult to diagnose and carry significant sequelae if untreated. Early surgical consultation is often needed for correction of the problem. This article reviews the pathophysiology of the most common pediatric testicular abnormalities with emphasis on the diagnostic modalities employed and current treatment alternatives.

Reproductive toxicity and tissue concentrations of low doses of 2,3,7,8-tetrachlorodibenzo-p-dioxin in male offspring rats exposed throughout pregnancy and lactation

The effects of low doses of 2,3,7,8-tetrachlorodibenzo-p-dioxin (TCDD) on the reproductive system of male offspring rats were examined. The dams were treated subcutaneously 2 weeks prior to mating and throughout mating, pregnancy, and lactation. They received an initial loading dose of 25, 60, or 300 ng TCDD/kg body wt, followed by a weekly maintenance dose of 5, 12, or 60 ng TCCD/kg body wt (TCDD 25/5, TCDD 60/12, and TCDD 300/60). Three dams per group were killed on Gestation Day 21 and the fetuses were removed. The concentration of TCDD in the maternal liver and fat was measured. After birth, developmental landmarks in male rats were monitored. At weaning, the concentration of TCDD in the offspring liver and testis was determined. Effects on male reproduction were studied on Postnatal Days (PND) 70 and 170. At weaning, the concentration of TCDD in the offspring liver was 0.24, 0.39, and 1.78 ng/g in the TCDD 25/5, TCDD 60/12, and TCDD 300/60 groups, respectively. In the testes, the concentration of TCDD was 0.25 ng/g in the TCDD 25/5 and TCDD 60/12 groups and 0.28 ng/g in the TCDD 300/60 group. The number of sperm per cauda epididymis was reduced in TCDD groups at puberty and at adulthood. Daily sperm production was permanently decreased as was the sperm transit rate in the TCDD-exposed male rats, thus increasing the time required by the sperm to pass through the cauda epididymis. Moreover, the male rats of the TCDD groups showed an increased number of abnormal sperm when investigated at adulthood. Similarly, mounting and intromission latencies were significantly increased in the TCDD 25/5 and TCDD 300/60 groups. In the highest dose group, serum testosterone concentration was decreased at adulthood. Likewise, in this dose group permanent changes including pyknotic nuclei and the occurrence of cell debris in the lumen were revealed. The lowest adverse effect level and the no observed effect level can be estimated to be substantially lower than the estimated daily dose of the lowest dose which is 0.8 ng/kg body wt/day. Sperm parameters were more susceptible than the other end points investigated. However, the question as to whether such doses exposed throughout gestation and lactation induce subtle changes in humans remains to be determined.

Analysis of testicular migration during the fetal period in humans

PURPOSE

We present an analysis concerning the testicular migration and its position correlated to body weight, crown-rump length and gestational age during the fetal period in humans without congenital abnormalities.

MATERIALS AND METHODS

We studied bilaterally 142 testes taken from 71 fresh human fetuses between 10 and 35 weeks after conception. The fetuses were also evaluated in regard to crown-rump length and body weight. The position of the testes was correlated to the fetal parameters.

RESULTS

In 37 fetuses (74 testes) at 10 to 23 weeks after conception only 7 testes (9.45%) had migrated from the abdomen and were situated in the inguinal canal, in 19 fetuses (38 testes) at 24 to 26 weeks after conception 22 testes (57.9%) had migrated from the abdomen and in 9 fetuses (18 testes) at 27 to 29 weeks after conception only 3 testes (16.7%) had not descended to the scrotum. The testes had not descended into the scrotum in any fetus weighing 990 gm. or less and with a crown-rump length of 24.5 cm. or less. On the other hand, in all fetuses weighing more than 1,220 gm. and with a crown-rump length of more than 27.5 cm. the testis was in the scrotum.

CONCLUSIONS

Until 23 weeks after conception the majority of testes remain in the abdomen. The more intense migration of the testes through the inguinal canal occurred between 21 and 25 weeks after conception. After 30 weeks after conception all testes were descended to the scrotum in all fetuses.

Cryptorchidism. Current concepts

Cryptorchidism is the most common genitourinary disorder of childhood. Even though its incidence has changed only slightly over the years, the number of operations for cryptorchid testes has tripled. Better understanding of the natural history of cryptorchidism, as well as changes that occur in testicular histology both in the cryptorchid and the contralateral descended testis very early in life, are the cause. This experience has led us to advocate early orchiopexy as the optimum means of treatment.

Prenatal phthalate causes cryptorchidism postnatally by inducing transabdominal ascent of the testis in fetal rats

Phathalate esters, which are commonly used as plasticizers for polyvinyl chloride, are also well known to disturb Sertoli cells. This study aims to show the effect of prenatally administered phthalate on testicular descent in pre- and postnatal rats. Pregnant rats were exposed to mono-n-butyl phthalate (MBP) by gavage from the 15th to the 18th gestational days. Rats administered with solvent only were used as controls. In 20-day-old fetuses (n = 15), the degree of transabdominal testicular ascent in relation to the bladder neck was thus found to be significantly higher in MBP-treated rats than that of the controls (n = 19). In addition, in MBP-treated male offspring (n = 26), 22 rats showed either bilateral or unilateral cryptorchidism at the age of 30 to 40 days old, and the occurrence of cryptorchidism was 84.6%. By contrast, the occurrence of cryptorchidism was 0% in the control rats (n = 15, P < .001). It is therefore suggested that prenatal exposure to MBP may disturb the Sertoli cells and elevate the fetal testes relative to the bladder neck while also inducing cryptorchidism postnatally. Sertoli cells may thus play an important role in the transabdominal descent of the testis by secreting Müllerian-inhibiting substance (MIS), which is known to act as a putative mediator of the transabdominal phase.

Primary gonadotropin releasing hormone and adjunctive human chorionic gonadotropin treatment in cryptorchidism: a clinical trial

OBJECTIVES

The effect of intranasal gonadotropin-releasing hormone (GnRH) and intramuscular human chorionic gonadotropin (hCG) in the treatment of cryptorchidism was investigated in 48 prepubertal boys.

METHODS

Forty-eight prepubertal boys with 70 undescended testes were enrolled into a prospective study between November 1989 and November 1991. GnRH was applied as nasal spray at a dose of 1.2 mg/day for 4 weeks. The patients with partial descent were subsequently treated with 1500 IU hCG weekly for 3 weeks.

RESULTS

Complete descent was observed in 53% (37 of 70) of testes; 58% (15 of 26) in unilateral and 50% (22 of 44) in bilateral undescended testes. One abdominally located testicle did not respond to therapy. Of 37 testes located in the inguinal canal, seven (19%) descended. On the other hand, descensus rates were 100% for the testes located at the external inguinal ring and at a high scrotal level. Six primarily descended testes (16%) showed relapse during the follow-up. Surgery was performed in 12 patients (14 testes), revealing associated hernia in nine testes and epididymal anomalies in four.

CONCLUSIONS

We believe that the GnRH and hCG combination is an effective therapy for undescended testes located at and beyond the external inguinal ring and should be the first treatment choice because of its noninvasiveness. Both unilateral and bilateral undescended testes responded with similar success rate to hormonal therapy. Surgery should be considered for proximal cryptorchidism.

Scanning electron microscopy shows inhibited gubernacular development in relation to undescended testes in oestrogen-treated mice

The morphological relationship between transabdominal testicular descent and the 'swelling reaction' of the gubernaculum was investigated in oestrogen-treated fetal mice by using scanning electron microscopy (scanning EM). In addition, flutamide was also administered to pregnant mice to determine whether androgens cause gubernacular growth and transabdominal testicular descent in offspring. In oestrogen-treated fetal mice, scanning EM showed that both the gubernacular 'swelling reaction' and transabdominal testicular descent were inhibited, in addition to inhibition of Müllerian duct regression. The gubernaculum showed a flat, thin bulb (widest diameter 0.25 +/- 0.04 mm) and an elongated cord (1.28 +/- 0.41 mm) after oestrogen treatment in utero, which was significantly different in appearance from that in normal control mice (width 0.44 mm +/- 0.06 mm, p < 0.001; length 0.27 +/- 0.19 mm, p < 0.0001). However, flutamide-treated mice showed much more normal gubernacular enlargement and transabdominal testicular descent. The width of the gubernacular bulb after flutamide exposure was 0.44 +/- 0.05 mm, which was comparable to that in control animals; the length of the intra-abdominal gubernaculum (0.44 +/- 0.15 mm) was slightly longer than in controls (p < 0.02). These results suggest that both the swelling reaction of the gubernaculum and transabdominal testicular migration are blocked by prenatal exposure to oestrogen. However, oestrogen exposure of the fetus does not block the swelling reaction of the gubernaculum by acting as an antiandrogen.

The pharmacological effect of the gonadotrophin-releasing hormone on experimental cryptorchidism in rats

Cryptorchidism is the most frequent congenital disturbance in males requiring both medical and surgical interventions. The involved testicle shows severe pathological changes. In an effort to test new medical treatments, we established a rat model for induced cryptorchidism using two estradiol treatment regimens and evaluated the effects of GnRH and an analogue D-Phe-GnRH on rate of testicular descent and on improvement of abnormal testicular histology. We found that the duration of estradiol treatment and not the total dose was related to delayed recovery from testicular descent. No significant effect of GnRH on testicular descent was observed. D-Phe-GnRH significantly improved the rate of testicular descent in rats treated 40 days with estradiol, but not in those treated 30 days with estradiol. The histologic examination of estradiol-induced undescended testes revealed severe morphological changes with a low number of germ cells, infiltration with lymphocytes, fibrosis and smaller diameter of seminiferous tubules. These changes were not improved with GnRH. D-Phe-GnRH was able to correct some of the histologic changes of estradiol-induced cryptorchidism. We established an animal model for testing of medical treatments for cryptorchidism. Our study may be indicative of a new treatment strategy using D-Phe-GnRH in the non-surgical treatment of cryptorchidism in human.

Current concepts in the pathophysiology of testicular undescent

At present, we believe that descent of the testes within the human is a complex event mediated by both hormonal and mechanical factors. We hypothesize that descent of the testes occurs as a result of the secretion of an androgen-independent factor from a normal testis (descendin). This paracrine factor is responsible for the rapid proliferation (outgrowth) of the ipsilateral gubernaculum. The development of the gubernaculum results in creating a dilated inguinal canal, the width of which matches the testicular width. Descent of the testes through the inguinal canal is an interplay between abdominal pressure, a patent processus vaginalis, and androgen-induced gubernacular regression. We hypothesize that androgens (under control of an intact hypothalamic pituitary axis) alter the viscoelastic properties of the gubernaculum, reducing the turgidity of the gubernaculum and allowing intra-abdominal pressure to push the testis into the scrotum. Cryptorchidism can therefore result when any one or more of the involved factors malfunction.

Antiandrogen induced cryptorchidism in the pig is associated with failed gubernacular regression and epididymal malformations

PURPOSE

Can antiandrogens cause cryptorchidism in an animal model with a strip-like gubernaculum? If so, what anatomical abnormalities are associated with cryptorchidism?

MATERIALS AND METHODS

Timed pregnant sows received the antiandrogen flutamide during defined gestational intervals. Fetal pigs were evaluated for the presence of testicular undescent and for morphological paratesticular abnormalities at 110 days of gestation (birth).

RESULTS

Of 180 testes 84 (47%) were undescended and 9 (5%) were in the abdominal cavity. No undescended testis (0 of 200 testes) were found in control animals (p < 0.001). Epididymal anomalies were found in all intra-abdominal testes, which was significant when compared to the epididymal abnormalities found with inguinal undescended testes (0%) or descended testes (1%) (p < 0.001). Alterations in gubernacular morphology, in particular failure of gubernacular regression, were also directly associated with cryptochidism (p < 0.001).

CONCLUSIONS

Androgens partially control transabdominal and transinguinal descent of the porcine testis. In addition, antiandrogen induced cryptorchidism is associated with epididymal malformation and failure of gubernacular regression. It remains to be determined if these latter findings are only associated with or the cause of testicular undescent.

Capsaicin increases the frequency of cryptorchidism in flutamide-treated rats

Capsaicin, a specific neurotoxin that irreversibly results in degeneration of sensory C fibers of the peripheral nerves, was investigated for its ability to affect testicular descent. In particular, we investigated the ability of prenatal flutamide, postnatal capsaicin or combined prenatal flutamide with postnatal capsaicin to induce undescended testes in rats. Within these treatment groups the frequency of maldescent was 42% in the animals treated prenatally with flutamide, 32% with postnatal capsaicin, and 100% with prenatal flutamide and postnatal capsaicin. Of interest, it was found that all animals that received capsaicin had maldevelopment of the scrotum. Our data suggest that capsaicin increased the frequency of cryptorchidism in rats prenatally treated with flutamide, perhaps by inhibition of scrotal development. These findings indicate that sensory nerves to the scrotum may affect scrotal development and testicular descent.

The effect of flutamide on testicular descent in rats examined by scanning electron microscopy

The effect of prenatal flutamide exposure on testicular descent was investigated by using scanning electron microscopy (SEM) in prenatal and postnatal rats. In 20-day-old fetal rats, SEM showed no significant difference in the degree of gubernacular development or testicular descent relative to the kidney between flutamide-treated (74.5 +/- 2.2 U) and control rats (73.3 +/- 1.5 U); however, there was significant inhibition in oestrogen-treated rats (44.3 +/- 2.2 U) (P < .001). (The distance between the kidney and the bladder neck was standardized to 100 U.) In 5-day-old rats, SEM showed inhibited downward growth of the processus vaginalis in flutamide-treated rats. The length of processus vaginalis below the inguinal ligament was 32.8 +/- 2.4 U in flutamide-treated rats and 51.7 +/- 1.8 U in controls (P < .001). In 30- to 35-day-old mature rats, the frequency of cryptorchidism was 41.3% for flutamide-treated rats and 0% for controls (P < .001). Some cryptorchid testes were located in the lower abdominal cavity (10.9%); others were in the suprainguinal position (26.1%) or on the line of descent in the inguinal region (4.3%). In the flutamide-treated group, no testes were located in the posterior abdominal cavity, near the kidney. These results suggest that transabdominal descent of the testis is independent of androgen action, but that androgens control inguinoscrotal descent of the testis by regulating gubernacular migration and the growth of the processus vaginalis.

Fertility after cryptorchidism: a comparative analysis of early orchidopexy with and without concomitant hormonal therapy in the young male rat

Infertility is common in patients with a history of bilateral cryptorchidism, even after successful prepubertal orchidopexy. Recent data suggest that this defect may be partially due to the existence of hormonal abnormalities in some forms of cryptorchidism. To analyze any potential benefit of hormonal therapy, we have evaluated the immediate and long-term effects of chronic hormonal therapy administered following surgical correction of cryptorchidism. First, using young male rats, we examined the effects of chronic human chorionic gonadotropin (HCG) and a luteinizing hormone-releasing hormone agonist (LHRH-A), alone or combined, on acute pituitary-gonadal axis responsiveness to LHRH administration. High doses of HCG and/or LHRH-A induced deleterious effects on the pituitary-testicular axis in terms of suppression of response to LHRH. Therefore, treatment with a low dose of HCG (50 U/kg/day) for 14 days was used, since it produced a significant increase in intratesticular testosterone (ITT). Second, we tested this hormonal regimen in a cryptorchid rat model. Bilateral cryptorchidism was produced by gubernaculum resection at 14 days of age. Early orchidopexy was performed at age 30 days, and HCG therapy was given from 31 to 44 days of age. Follicle stimulating hormone (FSH), luteinizing hormone (LH) and testosterone (T) levels were determined before and immediately after hormonal therapy, and at sacrifice. Animals were sacrificed at 61 days of age for determination of serum and testicular hormone levels, accessory sex organ weights and testis histology. Five or six animals from each group were retained for breeding studies at the age of 90 days. Hormonal alterations noted immediately following treatment of cryptorchid animals with HCG are not lasting. The data reveal that the fertility defect in bilateral cryptorchidism is partially prevented by early orchidopexy and that adjunctive hormonal therapy is probably of little additional benefit.

The fetal rat gubernaculum contains higher levels of androgen receptor than does the postnatal gubernaculum

The androgen receptor of the rat gubernaculum was measured by a sensitive immunoblotting technique from day 19 of fetal development to day 20 of postnatal development. In relative terms (densitometric units/microgram. protein), it was found that the amount of the gubernacular androgen receptor decreased dramatically from fetal to postnatal development, coincident with the transition of the gubernaculum from a tissue primarily composed of undifferentiated mesenchymal cells in the fetus to a tissue that is primarily made up of muscle during postnatal development. We conclude that the undifferentiated mesenchyme of the fetal gubernaculum is a primary target of androgen action.