Cremaster muscle is not sexually dimorphic, but that from boys with undescended testis reflects alterations related to autonomic innervation

Long-term Outcome of Laparoscopic Surgery for Nonpalpable Undescended Testis

Aims and Objectives

The aim of this study was to objectively assess the long-term results of laparoscopic orchidopexy in patients who were diagnosed clinically to have nonpalpable undescended testis (UDT).

Materials and Methods

All operated cases of nonpalpable UDT from January, 2000, to January, 2014, were reviewed. After informed consent, all patients were subjected to a color Doppler ultrasound examination to assess the location of the testis, its size, blood supply, and consistency. The size of the testis, operated and nonoperated, was noted down in volume using the formula of 0.71 × length × breath × height.

Results

A total of 114 patients could be identified, who had undergone laparoscopy for nonpalpable UDT in the study period. Of these, 44 patients (54 units) underwent a color Doppler study to assess the testes. All the testes were found to lie in the scrotum with preserved blood supply. The volume of the operated unilateral testes (mean = 1.605 cm3) was smaller than the normal nonoperated side (mean = 2.524 cm3). The smaller testicular volume was observed in spite of maintained blood supply to the testes. In cases of bilateral UDT, both the testes were smaller in size (mean = 2.2 cm3), but were comparable to each other. In addition, the ultrasound examination revealed the presence of normal homogenous parenchyma of all the testes similar to the nonoperated side.

Conclusion

Laparoscopic orchidopexy is a safe and effective option in the treatment of nonpalpable UDT. On a long-term basis, it is possible to achieve scrotal position along with preserved blood flow following laparoscopic orchidopexy in all patients suffering from nonpalpable UDT.

Isolation and characterization of myogenic precursor cells from human cremaster muscle

Human myogenic precursor cells have been isolated and expanded from a number of skeletal muscles, but alternative donor biopsy sites must be sought after in diseases where muscle damage is widespread. Biopsy sites must be relatively accessible, and the biopsied muscle dispensable. Here, we aimed to histologically characterize the cremaster muscle with regard number of satellite cells and regenerative fibres, and to isolate and characterize human cremaster muscle-derived stem/precursor cells in adult male donors with the objective of characterizing this muscle as a novel source of myogenic precursor cells. Cremaster muscle biopsies (or adjacent non-muscle tissue for negative controls; N = 19) were taken from male patients undergoing routine surgery for urogenital pathology. Myosphere cultures were derived and tested for their in vitro and in vivo myogenic differentiation and muscle regeneration capacities. Cremaster-derived myogenic precursor cells were maintained by myosphere culture and efficiently differentiated to myotubes in adhesion culture. Upon transplantation to an immunocompromised mouse model of cardiotoxin-induced acute muscle damage, human cremaster-derived myogenic precursor cells survived to the transplants and contributed to muscle regeneration. These precursors are a good candidate for cell therapy approaches of skeletal muscle. Due to their location and developmental origin, we propose that they might be best suited for regeneration of the rhabdosphincter in patients undergoing stress urinary incontinence after radical prostatectomy.

Infertility in rats subjected to genitofemoral nerve section is not associated with testicular damage

This work was aimed at assessing the relationship between testicular ascent and infertility induced by genitofemoral nerve (GFN) section in rats. Eighteen male rats were assigned to three experimental groups as follows: (i) Group SGFN was subjected to surgical section of genitofemoral nerve; (ii) Group Sham; (iii) Control group. The GFN was cut at puberty (28D), and the contralateral testis removed at 90D, with fertility tests at 120D. At 150D, maturity index, epithelial area and histopathological index of seminiferous tubules of all rats were determined and statistically compared between superior and inferior testicle poles, and between groups. There were no differences in testicular parameters, sperm morphology or sperm concentrations (P > 0.05). Section of NGF interfered with fertility (58.3 ± 15.4 in SGFN versus 83.3 ± 10.5 in Sham) and litter size (6.2 ± 1.1 in SGFN versus 10.7 ± 1.4 in Sham). Cremaster of SGFN group showed early neuropathy. The GFN section induced partial testicular ascent and diminished fertility without damage on testicular morphology or spermatic parameters, because, cremaster could affect the contractibility and ejaculation mechanisms in which it participates. The study of the damage on cremaster induced by an injury on GFN could have an overview of the mechanisms inherent in the testicular ascent induced by this iatrogenic alteration and their potential risks on fertility.

Long-term testicular position and growth of acquired undescended testis after prepubertal orchidopexy

PURPOSE

The aim of the study was to determine long-term testicular position and growth of acquired undescended testis (UDT) after prepubertal orchidopexy.

METHODS

Patients who had undergone prepubertal orchidopexy for acquired UDT at our hospital between 1986 and 1999 were recruited to assess long-term testicular position and volume. Testis position was assessed by physical examination. Testis volume was measured with Prader orchidometry and ultrasound and was compared with normative values reported in the literature.

RESULTS

A total of 105 patients (aged 14.0-31.6 years) were included with 137 acquired UDT (32 bilateral, 33 left sided, and 40 right sided). All but 1 of the orchidopexied testes (99.3%) were in low scrotal position. The mean volume of the orchidopexied testes in unilateral UDT (n = 73, 10.57 ± 3.74 mL) differed significantly from the size of the testes at the contralateral side (14.11 ± 4.23 mL) (P = .000). The operated testes (10.28 ± 3.45 mL) were smaller than the mean adult testis volume reported in the literature (13.4-13.6 mL; cutoff, 13.2 mL).

CONCLUSION

Testis position after prepubertal orchidopexy for acquired UDT was nearly always low scrotal. The volume of the orchidopexied testes was smaller than both the volume of the contralateral testes and the normative values reported in the literature.

The role of cremaster muscle in testicular descent in humans and animal models

Testicular descent is a complex developmental process involving anatomical and hormonal regulation. The gubernaculum undergoes a "swelling reaction" during the transabdominal phase and is mainly under the control of Insulin-Like Peptide 3 (INSL-3) and Mullerian Inhibitory Substance/Anti-Mullerian Hormone (MIS/AMH). The second phase of testicular descent is regulated by androgens and calcitonin gene-related peptide (CGRP) release from the sensory nucleus of the genitofemoral nerve (GFN). In rodents, the active proliferation of the gubernacular tip and cremaster muscle, its rhythmic contraction, as well as the chemotactic gradient provided by the CGRP result in eventual migration of the testis into the scrotum. This review illustrates the structural aspects and hormonal control of cremaster muscle development to better understand the mechanism of testicular descent in normal rodents and humans, compared to diseased rodent models. The analysis showed the cremaster muscle is formed from mesenchymal differentiation of the gubernacular tip and is not a direct passive extension of internal oblique muscle. Cremaster muscle matures slower than other body muscles, and the persistence of immature myogenic proteins seen in cardiac muscle allows rhythmic contraction to guide the testis into the scrotum. Finally, remodelling of the cremaster muscle enables gubernacular eversion. Further understanding of the molecular regulators governing the structural and hormonal changes in the cremaster muscle may lead to new advances in the treatment of undescended testes.

Sarco(endo)plasmic reticulum and plasmalemmal Ca(2+)-ATPase activities in cremaster muscles and sacs differ according to the associated inguinal pathology

Sarco(endo)plasmic reticulum Ca(2+)-ATPase (SERCA) and plasmalemmal Ca(2+)-ATPase (PMCA) activities in cremaster muscles and sacs, which have been subjected to different autonomic tonuses, were determined and compared. Samples of cremaster muscles and sacs associated with male or female inguinal hernia, hydrocele or undescended testis were obtained from children during operations and activities of SERCA and PMCA were determined. While highest SERCA and PMCA activities were encountered among cremaster muscles and sacs associated with undescended testis, least activities were encountered among structures associated with hydrocele. The alterations in SERCA and PMCA activities in cremaster muscles associated with undescended testis appear to reflect the attempts at maintaining the levels of cytosolic calcium. Despite similar total calcium contents, lower SERCA and PMCA activities were found in sacs associated with hydrocele compared to those associated with undescended testis suggest a difference among the levels of cytosolic calcium.

The role of sympathetic innervation in the developing rat gubernaculum

BACKGROUND

Testicular descent occurs in several steps, but the mechanism remains unknown. Recently, sympathetic nerves have been proposed to have a role. This study aimed to see if adrenergic agonists and antagonists affected the neonatal rat gubernacular cremaster sac in organ culture.

METHODS

Cremaster sacs were collected from 2-day-old Sprague-Dawley male rats (n = 90) and placed in organ culture with/without (1) calcium chloride (0.45-1.8 mmol/L), (2) rat calcitonin gene-related peptide (CGRP) (714 nmol/L), (3) nifedipine (0.1-100 nmol/L), (4) isopreneline (10 micromol/L), and (5) guanethidine (10 micromol/L). Gubernacula were observed over 2 days for rhythmic peristalsis (>120 beats per minute for >1 minute).

RESULTS

Addition of CGRP stimulated rhythmic contractility but only in the presence of calcium, with a dose-response to the level of calcium ions. Contractions induced by CGRP with calcium could be obliterated in a dose-response by nifedipine. Isoprenaline caused some increase in contractions with calcium but less than that seen with CGRP. No augmentation of effect was seen with CGRP and isopreneline together, and the level of contractility was the same with guanethidine.

CONCLUSIONS

Calcitonin gene-related peptide is the main effector for contractility of the rat cremaster sac, as long as calcium ions are present. Adrenergic agonists and antagonists had limited effects. Contractility could be inhibited with nifedipine, consistent with CGRP acting via a calcium-dependent pathway.

Does chemical sympathectomy alter the ontogeny of gubernacular migration in vivo?

BACKGROUND

Testicular descent occurs in several stages, but the exact mechanism remains obscure. Sympathetic nerves have been proposed to have a role by a possible action on developing cremaster muscle, following observations of sympathetic dysfunction in cremaster from boys with cryptorchidism. This study aimed to see if chemical sympathectomy affected testicular descent in rats.

METHODS

Sprague-Dawley dams were injected with 6-hydroxydopamine (days 15-19; 75 microg/kg) or control vehicle alone, and male pups examined at 0 to 10, 20, 30, and 60 days of age. The length of the processus vaginalis was measured and sections taken for histology.

RESULTS

No difference in processus vaginalis growth was found between experimental and control groups, both macro- and microscopically. Chemical sympathectomy was confirmed by loss of adrenergic fibres in the adrenal cortex of experimental, but not control, animals.

CONCLUSIONS

These studies suggest that sympathetic innervation is not an important part of testicular descent in the rat but does not exclude a pathologic role in undescended testes or effects in humans only.

Sensory, motor somatic, and autonomic neurons projecting to the porcine cremaster muscle

The location of sensory, somatic, and autonomic neurons projecting to the pig cremaster muscle (CM) was studied by means of the retrograde neuronal tracer Fast Blue (FB) technique. FB was randomly injected in the left CM of four impuberal pigs and serial sections of sensory and autonomic ganglia and spinal cord were examined under a fluorescence microscope. Additionally, some indications about the number and size of labeled neurons were given. Sensory pseudounipolar somata were located ipsilaterally in the L2-L6 and S1-S2 dorsal root ganglia, their total number ranging between 125 and 194, their mean diameter between 24 and 89 microm. Somatic multipolar motoneurons were located ipsilaterally in the L2-L4 neuromeres of the spinal cord, their total number ranging between 53 and 169, their mean diameter between 29 and 53 microm. Autonomic multipolar paravertebral ganglia neurons were located ipsilaterally from L1 to S4 and contralaterally from L2 to S2. Their total number ranged from 2,015 to 3,067 and their mean diameter between 25 and 55 microm. The multipolar caudal mesenteric ganglia neurons were located bilaterally, their total number ranging between 14 and 1,408 and their diameter from 22 to 39 microm. In two subjects only, multipolar neurons were also found ipsilaterally in the microganglia of pelvic plexus (2 and 13 neurons). Their mean diameter ranged between 28 and 54 microm. Our study documented that the CM-projecting neurons were located at different neural levels, with a predominance in the autonomic ganglia.

Androgen receptor immunostaining and androgen receptor messenger ribonucleic acid expression are increased in cremaster muscles associated with undescended testis

OBJECTIVES

To determine and compare androgen receptor (AR) immunostaining and AR messenger ribonucleic acid (mRNA) expression in cremaster muscles associated with descended or undescended testis.

METHODS

Eight boys with descended testis but with inguinal hernia and 8 boys with undescended testis were evaluated. Serum follicle-stimulating hormone (FSH), luteinizing hormone (LH), testosterone, and free testosterone levels were determined, and samples of cremaster muscles were immunostained for AR. Groups were compared by unpaired t tests and Fisher's exact tests; P values of <0.05 were considered significant. Samples of cremaster muscles were obtained from another 5 boys with descended testis but with inguinal hernia and 5 boys with undescended testis. The expression of AR mRNA in those samples was determined by semiquantitative reverse transcriptase polymerase chain reaction.

RESULTS

Serum FSH, LH, testosterone, and free testosterone levels were similar among groups. None of the samples from boys with descended testis showed positive staining, but 4 of 8 samples from boys with undescended testis stained positive for AR. Androgen receptor mRNA transcript levels were approximately 10 times lower in cremaster muscles of boys with descended testis compared with those in boys with undescended testis.

CONCLUSIONS

Despite similar serum hormone levels, more AR expression in cremaster muscles associated with undescended testis might represent evidence of being subjected to a lesser degree of androgenic effects.

Contractility of rat gubernacula affected by calcitonin gene-related peptide and beta-agonist

PURPOSE

The effects of calcitonin gene-related peptide (CGRP), isoprenaline, and guanethidine on the neonatal rat gubernaculum were investigated in organ culture with the aim of seeing whether beta -agonists or beta -antagonists are involved in gubernacular development during testicular descent.

METHODS

A total of 200 gubernacula were studied. The gubernacula (n = 20 for each experiment) from male rat pups were incubated in aerated culture medium with isoprenaline (1 and 10 micromol/L) with/without CGRP (714 nmol/L) or guanethidine (1 and 10 micromol/L) with/without CGRP (714 nmol/L). Cultures were observed for 5 days by video camera to see spontaneous rhythmic contractions, which are known to correlate with normal gubernacular migration in the rodent.

RESULTS

Of gubernacula cultured without CGRP, 60% showed contractions by day 5, and the groups of isoprenaline and 10 micromol/L guanethidine showed similar rates, but only 15% of the 1 micromol/L guanethidine group showed contractility (P < .005). In contrast, of the gubernacula cultured with CGRP, each group showed high contractility from day 2 of the culture, and there was no difference between each group and the CGRP-alone group.

CONCLUSIONS

Although the beta -blocker showed a weak inhibitory effect on de novo gubernacular contractility, CGRP had a stronger effect on contractility, overriding any possible effects of the beta -neuron pathway. The contractility of the rat gubernaculum during testicular descent is primarily mediated by the genitofemoral sensory nerve fibers via release of CGRP, but beta -adrenergic nerves also may be involved.

The role of smooth muscle cell differentiation in the mechanism of obliteration of processus vaginalis

BACKGROUND/PURPOSE

Development of indirect inguinal hernia and hydrocele in childhood is readily explained by the persistence of smooth muscle component around the processus vaginalis (PV) after the descent of the testis into the scrotum. The aim of this study was to investigate the expression of smooth muscle myosin heavy chain (SM MHC) isoforms as the markers of smooth muscle cell (SMC) differentiation in childhood inguinal hernia and hydrocele and in age-matched controls.

METHODS

The authors analyzed sacs from patients with inguinal hernia (male, 10; female, 10) and hydrocele (n = 10) immunohistochemically using monoclonal antibodies against alpha-smooth muscle actin, SM1, SM2 and SMemb. Peritoneal samples (male, 5; female, 5) obtained from age-matched patients served as controls. Immunostaining was evaluated with semiquantitative scoring and chi2 test.

RESULTS

The expression pattern of SM MHC isoforms did not differ among sacs obtained from female inguinal hernia when compared with that of controls. However, strong expression of SMemb within the sac walls of male inguinal hernia and SM1 in hydrocele groups were observed.

CONCLUSIONS

Our results indicate that SMC differentiation may play an important role in the obliteration of processus vaginalis in male inguinal hernia and hydrocele after the descent of the testis.

Chemical sympathectomy by 6-OH dopamine during fetal life results in inguinal testis through altering cremasteric contractility in rats

BACKGROUND/PURPOSE

Androgens are proposed to influence testicular descent through modulating sympathetic tone. An experimental study was undertaken to evaluate the effects of prenatal chemical sympathectomy on testicular location associated with the alterations in contractile properties of cremaster muscles in rats.

METHODS

Time-mated pregnancies were started in 10 rats. Two groups, each receiving saline or 6-hydroxydopamine from day 15 to day 19 of intrauterine life were established. At 2 months of age, localization of testes were evaluated, cremaster muscles were removed, and contractile properties were studied. Twitch and tetanic contractions were recorded isometrically at 37 degrees C. Effects of verapamil, isoprenaline, and L-NNA were investigated. Results were compared through analysis of variance (ANOVA), and P values less than.05 were considered to be significant.

RESULTS

Both testes of all male offspring in the control group (n = 19) were in the scrotum. Six offspring among 17 subjected to 6-hydroxydopamine had undescended testes. Treatment with 6-hydroxydopamine had no effect on force-frequency relationship of cremaster muscle strips. Cremaster muscles of rats exposed to 6-hydroxydopamine had lower sensitivity to voltage-sensitive Ca++ channel blockade by verapamil (3 x 10(4) mol/L; P <.05). These muscles displayed greater contractile response to isoprenaline (10(-5) mol/L; P <.05) but not to nitric oxide synthase inhibition by N(omega)-nitro-L-arginine. Alterations in contractile properties of the muscles did not differ according to localization of testes among rats subjected to 6-hydroxydopamine.

CONCLUSIONS

Administration of 6-hydroxydopamine resulted in suprascrotally located testes. This localization has been associated with less exposure at sympathetic tonus. These findings support that sympathetic activity plays an important role in localization of testis.

Less calcium in cremaster muscles of boys with undescended testis supports a deficiency in sympathetic innervation

In addition to an increase in contractility, contracted fibers and small and electron-dense mitochondria have suggested an increase of cytosolic Ca(2+) within the cremaster muscles (CM) associated with undescended testis. Therefore, the Ca(2+) content of CM associated with an undescended testis was determined and compared with the Ca(2+) content associated with inguinal hernia and hydrocele and in internal oblique muscles. CM samples from boys with undescended testis (n = 9), inguinal hernia (n = 15), and hydrocele (n = 7) and from girls with inguinal hernia (n = 8) were obtained. The calcium contents of these samples and of samples from internal oblique muscle (n = 6) were determined by atomic absorption spectrophotometry. While the Ca(2+) contents of CM from boys with undescended testis and from girls with inguinal hernia were similar (p > 0.05), the internal oblique muscle and the CM from boys with inguinal hernia and hydrocele contained more Ca(2+) than CM from boys with undescended testis (p < 0.05). Despite evidence of an increase in cytosolic calcium, the decrease in total calcium content suggests a decrease in the adenylyl cyclase activity, thus inhibition of influx of Ca(2+), but an increase in phospholipase C activity, and generation of more inositol 1,4,5-trisphosphate and mobilization of calcium from internal stores. Since the sympathetic system acts through adenylyl cyclase in striated muscles and is sexually dimorphic, similar Ca(2+) contents as encountered in girls suggest an alteration in the balance of autonomic innervation against the sympathetic system in boys with undescended testis.

Mechanisms involved in contractile differences among cremaster muscles according to localization of testis

BACKGROUND/PURPOSE

Evidence suggests differences in contractility in cremaster muscles (CM) associated with undescended testis caused by alterations of autonomic innervation. Contractile responses of CM to various pharmacologic agents were evaluated and compared according to the localization of testis.

METHODS

Samples of CM from boys with undescended testis or inguinal hernia were obtained. Twitch and tetanic contractions were recorded isometrically at 37 degrees C. Effects of verapamil, isoprenaline, calcitonin gene-related peptide (CGRP), substance P (SP) and N(omega)-nitro-L-arginine (L-NNA) were investigated. Results were compared through 2-way analysis of variance, and P values less than.05 were considered to be different.

RESULTS

Verapamil alone significantly (P <.05) decreased contraction amplitudes in CM from both sources; the decrease was more pronounced in CM from boys with inguinal hernia (P <.05). Although isoprenaline increased contraction amplitudes in CM associated with undescended testis (P <.05), CGRP and SP increased contraction amplitudes in CM associated with descended testis (P <.05). L-NNA increased contraction amplitudes in both groups (P <.05). The decrease of contraction amplitudes after verapamil displayed a similar pattern after isoprenaline, SP, and L-NNA. Verapamil-induced contractility decrease was more pronounced after CGRP in both groups (P <.05).

CONCLUSIONS

Sensitivity of CM to verapamil differs according to localization of testis. Isoprenaline enhances contractility by stimulating Na(+)-K(+)ATPase in undescended testis without altering voltage-sensitive channel sensitivity to verapamil. CGRP and SP increase contractility in inguinal hernia, and CGRP increases the sensitivity of voltage-sensitive Ca(2+) channels to verapamil in CM from both groups. Nitric Oxide (NO) exerts inhibitory action on CM contractility, and it is less pronounced in undescended testis. These differences may contribute to pathophysiology of undescended testis.

Cremasteric reflex and retraction of a testis

PURPOSE

A clinical study has been planned to define the clinical characteristics of cremasteric reflex (CR) for deciding on the possibility of a prolonged suprascrotal stay of a testis through this reflex.

METHODS

Five hundred boys from 3 days to 16 years of age were divided into 6 groups according to their ages and were evaluated for the presence of the CR. After evoking CR, the presence or absence of changes in testicular location and the most elevated position of the testis were recorded. Testicular position difference (TPD), the duration of the stay of testis in the most elevated position (DEP), and the interval for reevoking the CR (IRCR) were determined. The number of consecutive responses after repetitive evokings were recorded as reproducibility (R). Mean TPD, DEP, IRCR, and R values for both sides were calculated and compared among groups. The boys with a positive reflex were classified further according to their TPD, DEP, IRCR, and R values. Three groups were established according to the aforementioned criteria by dividing the values into 3 equal parts. The association of each of the parameters to other parameters were compared.

RESULTS

Bilateral positive CR was encountered in 42.7% of newborns, 36.3% of the boys between 1 month and 1 year old, 38.1% of the boys between 2 years and 4 years old, 75.2% of the boys between 5 years and 8 years old, 70.3% of the boys between 9 years and 12 years old, and 72.1% of the boys between 13 and 16 years old. The highest percentage of the contralateral activations during ipsilateral evokings were encountered in boys who were between 5 and 8 years of age. The highest mean TPD and mean R, the longest mean DEP, and mean IRCR were encountered in boys between 5 and 8 years of age. Boys with the highest TPD did not have shortest IRCR and highest R values. Similarly, boys with the longest DEP or shortest IRCR and highest R values did not have the association of other parameters that would suggest a hypersensitivity.

CONCLUSIONS

The rate of presence and the characteristics of a positive CR vary largely. However, suprascrotal location of a testis for extended periods through the activation of this reflex does not seem to be likely. Instead of a hyperactive reflex, the clinical condition, so called the retractile testis, might have resulted through alterations within the cremaster muscle itself. J Pediatr Surg 36:863-867.