Penile tumescence in the human fetus at term--a preliminary report

Imaging in fetal genital anomalies

Genital anomalies are a heterogeneous group of congenital pathologies that have become increasingly relevant since the Chicago Consensus of 2005. Their postnatal diagnosis has developed significantly in the last two decades, while prenatal diagnosis seems to be underdeveloped, with few protocols available, fragmented scientific literature, and low diagnostic rates. This review aims to examine the current status of this subspecialty from the perspective of prenatal imaging. Indications for the evaluation of fetal genitalia can be divided into medical and non-medical reasons. Medical reasons include sex-linked disorders, detection of other anomalies, relevant family history, or multiple pregnancy. Non-medical reasons include parental request for sex disclosure. Disclosure of fetal sex may be associated with ethical, legal, and medical issues. The main imaging technology used is 2D ultrasound, although there are other complementary techniques such as 3D, MRI, or Color Doppler. Regarding working methodology, several authors have drawn attention to the lack of standardized protocols and guidelines. Most guidelines tend to limit their recommendations to study indications and ethical issues. Technical proposals, measurements, or working methods have not yet been standardized. Fetal sex determination is usually divided into early and late gestation. Early gestation is based on the sagittal sign. Late gestation is based on direct visualization. There are several measurements to describe male and female genitalia, such as penile length, bilabial diameter, or scrotal diameter. Prenatal diagnosis of genital pathologies presents some particularities such as the wide spectrum of phenotypes, the high frequency of associated deformities, or the time of diagnosis. Some of the most frequent pathologies are ambiguous genitalia, fetal sex discordance, hypospadias, micropenis, clitoromegaly, ovarian cysts, hydro(metro)colpos, and cloacal anomalies. Higher-quality studies and direction from scientific societies through the implementation of clinical guidelines are needed.

From Acellular Matrices to Smart Polymers: Degradable Scaffolds that are Transforming the Shape of Urethral Tissue Engineering

Several congenital and acquired conditions may result in severe narrowing of the urethra in men, which represent an ongoing surgical challenge and a significant burden on both health and quality of life. In the field of urethral reconstruction, tissue engineering has emerged as a promising alternative to overcome some of the limitations associated with autologous tissue grafts. In this direction, preclinical as well as clinical studies, have shown that degradable scaffolds are able to restore the normal urethral architecture, supporting neo-vascularization and stratification of the tissue. While a wide variety of degradable biomaterials are under scrutiny, such as decellularized matrices, natural, and synthetic polymers, the search for scaffold materials that could fulfill the clinical performance requirements continues. In this article, we discuss the design requirements of the scaffold that appear to be crucial to better resemble the structural, physical, and biological properties of the native urethra and are expected to support an adequate recovery of the urethral function. In this context, we review the biological performance of the degradable polymers currently applied for urethral reconstruction and outline the perspectives on novel functional polymers, which could find application in the design of customized urethral constructs.

Assessment of the septal area neuronal activity during penile erections in rapid eye movement sleep and waking in the rats

To understand the central mechanism of penile erections during rapid eye movement (REM) sleep and waking, single units were recorded from the septal area in un-anesthetized head-restrained rats simultaneous with erections. Erectile events were assessed by pressure in the bulb of the corpus spongiosum of the penis and bulbospongiosus-muscle activity. Of 143 recorded neurons, 36% showed increased activity (E-type) and 24% decreased activity (I-type) during different phases of erection in REM sleep, while 10% were E-type and 35% were I-type during erections in waking. Most E-type neurons were recorded from the dorsal and intermediate part of lateral septum, whereas I-type neurons were from the medial septum. The findings illustrate the extensive network of various types of neurons in the septal area that fire in concert in relation to erection during REM sleep and waking. This study provides a unique prospective of the septal area for perpetuation of erectile circuitry during sleep.

In utero gratification behaviour in male fetus

Fetal masturbation has been described previously once in utero but only as a description of an action. Masturbation is well described in infancy and early childhood when they discover that this practice can give them pleasure. Our letter proves that it could begin in utero as a 'gratification behaviour'. We have shown this pattern clearly by using a volumetric rendering mode study. © 2016 John Wiley & Sons, Ltd.

Development of the penis during the human fetal period (13 to 36 weeks after conception)

PURPOSE

We analyzed the development of the area of the penis and erectile structures (corpora cavernosa and corpus spongiosum) and the thickness of the tunica albuginea during the fetal period (13 to 36 weeks after conception) in humans to establish normative patterns of growth.

MATERIALS AND METHODS

We studied 56 male human fetuses at 13 to 36 weeks after conception. We used histochemical and morphometric techniques to analyze the parameters of total penile area, area of corpora cavernosa, area of corpus spongiosum, and thickness of tunica albuginea in the dorsal and ventral regions using ImageJ software (National Institutes of Health, Bethesda, Maryland).

RESULTS

Between 13 and 36 weeks after conception the area of the penis varies from 0.95 to 24.25 mm2. The area of the corpora cavernosa varies from 0.28 to 9.12 mm2, and the area of the corpus spongiosum varies from 0.14 to 3.99 mm2. The thickness of the tunica albuginea varies from 0.029 to 0.296 mm in the dorsal region and from 0.014 to 0.113 mm in the ventral region of the corpora cavernosa.

CONCLUSIONS

We found a strong correlation between the total penile area, corpora cavernosa and corpus spongiosum with fetal age (weeks following conception). The growth rate was more intense during the second trimester (13 to 24 weeks of gestation) compared to the third trimester (25 to 36 weeks). Tunica albuginea thickness also was strongly correlated with fetal age and this structure was thicker in the dorsal vs ventral region.

Reference values for fetal penile length and width from 22 to 36 gestational weeks

OBJECTIVE

Current reference range values for fetal penile growth are based on length measurements. However, methodologies for measuring penile length differ among studies and from the standard technique used in children. We propose that the measurement of penile width may aid in its evaluation. The aim of the study was to create normograms for penile length and width.

METHODS

A prospective cross-sectional design was used. One hundred male fetuses at 22 to 36 gestational weeks were included. On ultrasound examination, penile length was measured from tip to base, where the penis joins the scrotum. Penile width was measured at the widest point across the penis. Reference values for the 5th and 95th percentiles were calculated for each gestational week.

RESULTS

There was a good correlation between gestational age and penile length (R(2) = 0.606) and width (R(2) = 0.683). The percentile of fetal weight estimation independently affected penile length and width. The interobserver correlation coefficient was 0.939 for length and 0.909 for width.

CONCLUSION

Reference range values of fetal penile length and width are presented for 22 to 36 weeks of gestation. These values correlate to gestational age and estimated fetal weight percentile. These reference range measurements may help the evaluation of suspected micropenis.

Update on corpus cavernosum smooth muscle contractile pathways in erectile function: a role for testosterone?

INTRODUCTION

Normal erectile function (EF) involves a coordinated relaxation of the arteries that supply the penis and the corpus cavernosum smooth muscle (CCSM), resulting in expansion of the sinusoids and increased intracavernous pressure. But the CCSM spends the majority of its time in the contracted state which is mediated by norepinephrine released from nerve endings and other vasoconstrictors like endothelins released from the endothelium. These agents cause smooth muscle myosin (SMM) phosphorylation by elevating intracellular calcium. When calcium returns to basal levels, the calcium sensitivity increases and prevents myosin dephosphorylation, which involves the RhoA/Rho-kinase (ROK) mechanism, thus maintaining force. Although mounting evidences demonstrate that androgens have a major influence on EF that is not just centrally mediated, this notion remains quite controversial.

AIM

To summarize the current knowledge on CCSM contractile pathways, the role they play in modulating EF, and the influence of androgens.

METHODS

The article reviews the literature and contains some previously unpublished data on CCSM contraction signaling including the role that androgens are known to play in modulating these pathways.

MAIN OUTCOME MEASURES

Data from peer-reviewed publications and previously unpublished observations.

RESULTS

In addition to downregulation of many pro-erectile molecular mechanisms, decreased testosterone (T) levels upregulate CCSM contractility, including hyperresponsiveness to α-adrenergic agonists, increased SMM phosphorylation, alteration of SMM isoform composition, activation of RhoA/ROK signaling and modulation of sphingosine-1-phosphate regulation of CCSM tone.

CONCLUSIONS

Decreased T levels upregulate CCSM contractile signaling. Meanwhile, it downregulates CCSM relaxation pathways synergizing to produce erectile dysfunction (ED). Although some urologists and researchers are still skeptical of the influence of androgens on penile erection, understanding these molecular control mechanisms as well as the influence that androgens have on these pathways should provide new evidence supporting the roles of androgens in EF and enhance the discovery of novel targets for drug development to treat ED.

The concentration of elastic fibres in the male urethra during human fetal development

OBJECTIVE

To describe the distribution of elastic fibres in the developing male urethra and to provide stereological data of the concentration of elastic fibres in the human urethra.

MATERIALS AND METHODS

Urethras were obtained from 10 fresh normal human fetuses at 15-36 weeks of gestation. A place-matched spongy urethra of a 27-year-old normal adult man was also analysed. Samples were fixed in Bouin's solution, embedded in paraffin and histologically processed. The elastic system fibres were evaluated by light microscopy using Weigert's resorcin-fuchsin technique after oxidation. Morphometric values were assessed by the point-counting method. The volumetric density (Vv) of elastic fibres was correlated with fetal age.

RESULTS

At 15 weeks the elastic fibres were sparse and homogeneously distributed. The size and thickness of elastic fibres increased with age, mainly in the third trimester of gestation. Elastic fibres formed a randomly orientated network in the trabeculae of the corpus spongiosum. The mean (sem) Vv of elastic fibres in the spongy urethra was 5.2 (0.4)% in the fetus at 15 weeks and 14.8 (1.0)% at 36 weeks. In the urethra of the place- matched young man the Vv was 19.0 (1.3)%. The concentration of elastic fibres in the spongy urethra increased significantly with age.

CONCLUSION

The high concentration of elastic fibres in the spongy urethra may partly explain its high extensibility. The progressive increase in elastic fibres during development implies functional adaptation of the fetal male urethra.

Androgens regulate phosphodiesterase type 5 expression and functional activity in corpora cavernosa

By real-time RT-PCR and Western blot analysis, we found that phosphodiesterase type 5 (PDE5) mRNA and protein abundance was several fold higher in human male than in female reproductive tracts. The highest mRNA level (>1 x 10(7) molecules/microg total RNA) was detected in human corpora cavernosa (CC), where PDE5 protein was immunolocalized in both muscular and endothelial compartment. The possible role of androgens in regulating PDE5 expression was studied using a previously established rabbit model of hypogonadotropic hypogonadism. In this model, hypogonadism reduced, and testosterone (T) supplementation restored, CC PDE5 gene and protein expression. In addition, T supplementation completely rescued and even enhanced cyclic GMP conversion to metabolites, without changing IC(50) for sildenafil (IC(50) = 2.16 +/- 0.62 nm). In control CC strips, sildenafil dose-dependently increased relaxation induced by electrical field stimulation, with EC(50) = 3.42 +/- 1.7 nm. Hypogonadism reduced, and T increased, sildenafil effect on electrical field stimulation, again without changing their relative EC(50) values. CC sensitivity to the NO-donor NCX4040 was greater in hypogonadal rabbit strips than in control or T-treated counterparts. Moreover, sildenafil enhanced NCX4040 effect in eugonadal rabbit strips but not in hypogonadal ones. This suggests that androgens up-regulate PDE5 in rabbit penis. We also measured PDE5 gene expression and metabolic activity in human CC from male-to-female transsexual individuals, chronically treated with estrogens and cyproterone acetate. Comparing the observed values vs. eugonadal controls, PDE5 mRNA, protein, and functional activity were significantly reduced. In conclusion, we demonstrated, for the first time, that androgens positively regulate PDE5, thus providing a possible explanation about the highest abundance of this enzyme in male genital tract.

Contextual approaches to the physiology and classification of erectile function, erectile dysfunction, and sexual arousal

This paper offers a reexamination of some long-held beliefs relating to the physiology of erectile function and dysfunction, including the idea that there is a singular physiology of erection. Rather, there appear to be plural neural, neurochemical, and endocrine mechanisms whose participation in erectile function depends on the behavioral context in which erection occurs. The best examples of this context-dependent physiology come from research on rats. For example, the medial amygdala is essential for noncontact erection in response to inaccessible estrous females, but not for erection during copulation. Also, androgen is necessary for touch-based and noncontact erection, but not for erection during copulation. Even the specific dopamine receptors important to erection may differ, depending on the context. If there is not a singular physiology of erection, then it follows that the physiology of erectile dysfunction may also vary from context to context. Thus, some disorders of the central nervous system may not be manifested in sleep-related erection, and therefore may be misinterpreted as "psychogenic" erectile dysfunction. This term belies the axiom that all psychological processes have a somatic basis; therefore, there can be no psychogenic dysfunction that does not involve organic processes which may respond to pharmacotherapy. A revised classification of erectile dysfunction based on this premise is offered. Finally, closer attention to erectile context may also illuminate male "sexual arousal" and its relation to "sexual motivation". The former term has so many meanings in current usage as to impede research, especially into the physiology of sexual arousal, which depends on comparisons between animals and humans. It is proposed that attention be given to two variables: whether or not erection occurs and whether or not the context is sexual. The occurrence of penile erection within a sexual context is viewed as the only case in which sexual arousal may be inferred unambiguously.

Rhythmic changes in the stomach movement of the human fetus with congenital duodenal obstruction during the third trimester of pregnancy

In order to reveal whether or not rhythmic changes exist in fetal stomach movement (FSM), in utero FSM was assessed in three fetuses between 27 and 33 weeks' gestation with congenital duodenal obstruction. A total of four observations, one each at 27, 29, 31 and 33 weeks' gestation, was obtained. The longitudinal transection of each fetal stomach was continuously observed for 60 min using real-time ultrasound. The configuration and the area of the stomach were analyzed for each 15-s epoch. The complexity of the stomach configuration was quantified and defined as stomach complexity. For each case, the chronological changes of the stomach complexity were analyzed using the least median square of regression. The correlation between changes of the stomach complexity and the area of the stomach was analyzed using the cross-correlation method. (1) For gestational ages of 27, 29, 31 and 33 weeks, the 240 sequential measurements of the stomach complexity were significantly stratified into outlying and non-outlying points. The outlying points were 13.3% (32/240), 30.8% (74/240), 32.9% (79/240) and 36.3% (87/240) of the total observation points, respectively. (2) The percentages in which outlying points lasted 3 min (12 points) or more were 0% (0/240), 5.0% (12/240), 28.3% (68/240) and 30.4% (73/240) of the total observation points, respectively. (3) For each gestational age, no significant time series correlation was found between the stomach complexity and the area of the stomach. These findings suggest that: (1) two different conditions emerge in the FSM, at the latest at 27 weeks' gestation, and begin manifesting from 29 weeks' gestation onwards. (2) These chronological changes cluster into 'active' and 'quiet' phases from 31 weeks' gestation onwards. (3) FSMs are not related to the changes in the stomach area throughout the observation periods. The underlying mechanism of this rhythmicity may represent the development of ultradian rhythm of the stomach movement, generated by the central nervous system.

Quantitative analysis of smooth muscle fibers in corpus cavernosum of human fetuses

PURPOSE

Quantify objectively the normative distribution and the percentage of smooth muscle fibers in the corpus cavernosum of human fetuses with 24 weeks post-conception (WPC) of gestational age.

MATERIAL AND METHODS

We studied 7 penises taken from 7 fresh human fetuses. We analyzed 5 randomized sections from each penis and in every section we analyzed 3 fields, totaling 15 fields per penis and 105 fields for the final results. Immunohistological staining for the smooth muscle fibers was used to accentuate the differences between the intracavernous structures (smooth muscle fibers and collagen fibers). The fields studied were digitized with a final magnification of 450X and a computerized analysis of the smooth muscle fibers was performed with image analyzer software. The percentage of smooth muscle fibers per standard square area was estimated and the mean value was used for each penis.

RESULTS

The distribution of smooth muscle fibers in the corpus cavernosum of human fetuses with 24 WPC of gestational age ranged from 17.52% to 27.76% of the total area. The mean value was 22.72% and the standard deviation was 3.56.

CONCLUSIONS

Our results show that the percentage of smooth muscle cells in corpus cavernosum of human fetuses with 24 WPC of gestational age is significantly smaller when compared with the data available for adult cadavers.