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S'il existe un spectre de 11 méthodes contraceptives différentes pour les femmes, il n'y en a que 3 couramment utilisées par les hommes : le préservatif et le retrait, avec leur taux d'échecs élevés, ainsi que la vasectomie, considérée comme une méthode irréversible. Depuis 40 ans, de nombreuses études ont été réalisées pour développer des contraceptifs masculins hormonaux et non hormonaux sûrs et efficaces. Bien qu'elles aient fait la preuve de leur efficacité, les contraceptions masculines hormonale et thermique restent encore peu utilisées. Les principes, protocoles, efficacité, réversibilité et acceptabilité de ces deux méthodes sont présentées, ainsi que les éléments pratiques, pour leur prescription et leur suivi. Nous décrivons également de nouvelles méthodes en cours de développement (contraceptifs hormonaux masculins oraux ou transdermiques, méthodes d'occlusion déférentielle). D'autres recherches sont nécessaires pour l'amélioration et la diffusion de méthodes contraceptives masculines efficaces, réversibles et sûres qui permettront aux hommes autant qu'aux femmes de jouer un rôle actif dans la planification familiale. Although the spectrum of women contraceptives includes 11 different methods, only 3 are commonly used by men: condoms, withdrawal, which has a high failure rate, as well as vasectomy, considered as an irreversible method. Over the past 40 years, numerous studies have been carried out to develop safe and effective hormonal and non-hormonal male contraceptives. Although their effectiveness has been proven, hormonal and thermal male contraceptions are still little used. The principles, protocols, effectiveness, reversibility and acceptability of these two methods are presented, as well as the practical elements for their prescription and monitoring. We also describe new methods under development (male oral or transdermal hormonal contraceptives, deferential occlusion methods). Further research is necessary to improve and market effective, reversible and safe male contraceptive methods which will enable men and women to play an active role in family planning. [ABSTRACT FROM AUTHOR]

In cryptorchid boys, failures in germ cell development have been clearly established. Some studies reported some abnormalities in Sertoli cells morphology but the results regarding their endocrine secretion remain controversial. To compare testicular hormone levels in young boys with and without cryptorchidism, we performed a cross-sectional hospital-based study. From surgery appointment records, we identified a case group of boys with unilateral or bilateral cryptorchidism and a control group undergoing dental care, minor osteoarticular or dermal surgery. Blood samples were withdrawn during the surgical procedure to perform testosterone, inhibin B and anti-müllerian hormone ( AMH) immunoassays. We included 27 cryptorchid boys and 27 controls aged of 26.6 vs. 24.2 months, respectively ( p = 0.172) far from the post-natal mini-puberty and the corresponding hormonal surges. Age-adjusted AMH and inhibin B levels were significantly lower in cryptorchid than in control boys ( AMH: 87 ng/ mL vs. 135 ng/ mL; p = 0.009, inhibin B: 97 pg/ mL vs. 133 pg/ mL; p = 0.019, respectively). Moreover, AMH and inhibin B levels were significantly lower in the bilateral cryptorchid subgroup, being 50% lower than in the controls ( p = 0.011 and 0.019, respectively) and while both hormones levels were independent in controls, they became strongly correlated in bilateral cryptorchid boys ( R² = 0.75, p = 0.001). In addition, testosterone levels were still detectable in some boys, with significantly lower levels in cryptorchid group than in controls. Overall, 2-year-old cryptorchid patients presented a simultaneous and significant drop in AMH and inhibin B levels, suggesting a functional defect of Sertoli cells. This deficiency appeared more pronounced in bilateral cryptorchidism and thus, regarding the pivotal role of Sertoli cells in germ cell development, it may explain the compromised fertility found later in men born with such a malformation. [ABSTRACT FROM AUTHOR]

Objectives:To evaluate the efficacy of anticholinergic agents in the treatment of neurogenic overactive bladder (NOAB) and neurogenic detrusor overactivity (NDO) in spinal cord injury (SCI) patients on clean intermittent catheterisation (CIC).Methods:Chronic suprasacral SCI patients on CIC presenting with at least one urinary leakage a day were included. Urodynamics and voiding diaries were performed at baseline and 1 month follow-up. In case of NDO at baseline, an anticholinergic drug was prescribed.Results:The 231 SCI patients presented with one to five urinary leakages per day (mean 2.1). Urodynamics showed NDO in all patients. A new anticholinergic treatment was started in all, either in monotherapy (134 patients) or in association with the existing anticholinergic drug (oxybutynin+trospium bitherapy, 97 patients). The mean maximum bladder capacity significantly increased from 225 to 441 ml, and the mean involuntary detrusor contractions (IDC) significantly decreased from 67 to 41 cm H2O. Only 75 SCI patients (32%) were fully continent. However, 25 out of these 75 patients showed persistent NDO, with amplitudes of IDC above 40 cm H2O in 12 patients. Incontinence was still found in 156 SCI patients (67%), with an average of 1,2 leakages a day. In 100 patients, amplitudes of IDC remained above 40 cm H2O. There was no statistical difference between patients on anticholinergic monotherapy or bitherapy at follow-up.Conclusion:Anticholinergic treatment is not always satisfactory in terms of control of NDO and rarely allows full continence. Urodynamic follow-up is mandatory in all patients, even in those showing clinical continence. [ABSTRACT FROM AUTHOR]

An international workshop titled 'Assessing Endocrine-Related Endpoints within the First Years of Life' was held 30 April-1 May 2007, in Ottawa, Ontario, Canada. Representatives from a number of pregnancy cohort studies in North America and Europe presented options for measuring various endocrine-sensitive endpoints in early life and discussed issues related to performing and using those measures. The workshop focused on measuring reproductive tract developmental endpoints [e.g., anogenital distance (AGD)], endocrine status, and infant anthropometry. To the extent possible, workshop participants strove to develop or recommend standardized measurements that would allow comparisons and pooling of data across studies. The recommended outcomes include thigh fat fold, breast size, vaginal cytology, AGD, location of the testis, testicular size, and growth of the penis, with most of the discussion focusing on the genital exam. Although a number of outcome measures recommended during the genital exam have been associated with exposure to endocrine-disrupting chemicals, little is known about how predictive these effects are of later reproductive health or other chronic health conditions. [ABSTRACT FROM AUTHOR]

Testicular cancer is the most common neoplasia occurring in the young male population. The PEB (cisplatin, etoposide and bleomycin) adjuvant chemotherapy usually proposed after orchidectomy in non seminomatous tumours, and in metastatic seminomas, has improved the long-term survival of these patients. Following an azoospermic period, sperm cell recovery is generally observed after treatment delivery, but little is known about the genetic consequences on these new spermatozoa. To estimate the chromosomal consequences of this chemotherapy on sperm cells during the period of recovery of spermatogenesis, sperm cell aneuploidy was studied in testicular cancer patients, at 6–18 months after PEB adjuvant chemotherapy delivery, using fluorescence in-situ hybridization (FISH) of chromosomes 7, 16, 18, X and Y with specific DNA probes. A significant increase in the frequency of diploidy and disomy for chromosomes 16, 18 and XY was observed in treated patients compared with a healthy control group. Spermatozoa aneuploidy occurring during the spermatogenesis recovery period might be a possible side effect of the PEB regimen. Thus, practitioners should be advised to provide counselling about the need for an appropriate duration of contraception. Moreover, genetic counselling should be offered in cases of pregnancy occurring soon after the end of chemotherapy. [ABSTRACT FROM PUBLISHER]

In humans, as in most mammals, spermatogenesis is temperature dependent. This temperature dependence has been clearly demonstrated by several experimental studies showing that artificial increases in scrotum or testicle temperature in fertile men reduce both sperm output and quality. Our knowledge of the effects of occupational heat exposure on male fertility comes mostly from a small number of epidemiological studies. We conducted an extensive review of these published reports, focusing on methodology and design (retrospective or prospective; reference group; number of subjects) and principal results (using several indicators such as the time taken to obtain a pregnancy or sperm characteristics). We concluded that occupational heat exposure is a significant risk factor for male infertility, affecting sperm morphology and resulting in delayed conception. The limits and biases involved in this type of research are also discussed. [ABSTRACT FROM AUTHOR]

The aim was to determine whether proton magnetic resonance spectroscopy (1H-MRS) of metabolites such as glycerophosphorylcholine (GPC), choline, citrate and lactate in human seminal plasma can be used to differentiate (i) different azoospermic patients and (ii) different forms of spermatogenic failure including those who had undergone radiation therapy or chemotherapy. Semen samples were provided by men with obstructive azoospermia and spermatogenic failure who had serum follicle stimulating hormone (FSH) values within the normal range and either more or less than normal. Four prominent constituents of seminal plasma were identified by 1H-MRS: GPC, choline, citrate and lactate. The peak area ratios of choline/citrate as well as choline/lactate were significantly different (P < 0.01) between groups with spermatogenic failure and obstructive azoospermia. When the serum FSH values were normal in men with spermatogenic failure and obstructive azoospermia, a significant difference was found in the GPC/choline ratio (P < 0.001). When the FSH values were normal, the GPC/choline ratio appeared to be a very important parameter able to differentiate not only between cases of spermatogenic failure and obstructive azoospermia but also between different forms of spermatogenic failure. These results demonstrate the potential use of 1H-MRS on human seminal plasma in a new approach in the management of male infertility. [ABSTRACT FROM AUTHOR]

The presence of cytomegalovirus (CMV) in semen was retrospectively evaluated in 178 cryopreserved semen samples obtained from 97 donors recruited by two sperm banks. Thirty-three (34.0%) donors were CMV-seronegative, 51 (52.6%) were CMV-seropositive and 13 (13.4%) had an unknown serological status. CMV was detected in sperm specimens by cell culture and polymerase chain reaction (PCR). CMV was detected in five (2.8%) samples from two (2.0%) donors by cell culture and in 10 samples (5.6%) from five donors (5.1%) by PCR; all the samples which were positive by cell culture were also positive by PCR. Our data indicate that cryopreserved semen specimens obtained from healthy volunteer donors represent a potential source of CMV infection through therapeutic donor insemination. PCR, which is more sensitive than cell culture, should be used for direct and rapid identification of CMV in semen samples collected from volunteer donors. CMV detection in semen by PCR could be advantageously compared to CMV-antibody tests in serum which are only indicative of a former CMV infection. [ABSTRACT FROM PUBLISHER]

The usual testicular location, either low or high in the scrotum, as well as testis ascent into suprascrotal position at least once a week from a usually scrotal position reported by the patient to occur spontaneously and regularly, were recorded in 85 fertile and 1014 infertile men, including 95 with a history of cryptorchism. The frequency of at least one testis being in a high scrotal location was similar in fertile (16.5%) and non-cryptorchid infertile (17%) men but higher in previously cryptorchid infertile men (27.2%), a difference probably due to cryptorchism. Testicular ascent was more frequent when scrotal location was high rather than low. An ascending testis was encountered more frequently in previously cryptorchid (30.4%) than in non-cryptorchid infertile men without any history of cryptorchism (18.3%) or in fertile men (11.8%). Moreover, in infertile men, spermatogenesis was more depressed in cases of testicular ascent than when both testes were never ascending, independently of a varicocele. Testis ascent could be a risk factor for spermatogenesis in infertile men without any history of maldescended testicle. [ABSTRACT FROM PUBLISHER]

Out of 85 fertile and 1014 infertile men, two (2.4%) and 95 (9.4%) respectively had a history of cryptorchidism. Thus cryptorchidism appears to be a risk factor for fertility since this difference was significant. Further comparisons showed that the volume of a former cryptorchid testis was smaller than the contralateral normally descended one and that sperm output/concentration was more impaired in bilateral than in unilateral cryptorchidism. A retractile testis, defined as a testis reported by the patient to be spontaneously and regularly, i.e. at least once a week, ascending up into a supra-scrotal position, was more frequent in infertile men with a history of cryptorchidism than in fertile men. Retractility was more frequent on the cryptorchid side, and was found more frequently after hormonal than after surgical treatment. Independently of all epidemiological and clinical parameters studied, retractility was associated with a lower sperm output. Among the infertile men with a history of cryptorchidism, 45% had an abnormally high scrotal temperature. This abnormal temperature represented a pejorative risk factor for fertility in this group, since it was associated with a more severely impaired spermatogenesis and a higher incidence of primary infertility than in infertile men with a history of cryptorchidism but normal scrotal temperatures. [ABSTRACT FROM PUBLISHER]

Seminal hormonal patterns in fertile and infertile men were investigated. Follicle-stimulating hormone (FSH), luteinizing hormone (LH), prolactin, testosterone and oestradiol were assessed by radioimmunoassay, and dehydroepiandrosterone sulphate (DHAS) by bioluminescence assay, on blood and seminal plasma of 23 fertile men and 83 infertile men. For fertile men, mean FSH, LH, testosterone and DHAS concentrations were lower and mean oestradiol was higher in seminal than in blood plasma; prolactin did not differ. For infertile men, mean seminal FSH and LH showed a moderate but significant increase compared with fertile men; testosterone, DHAS and prolactin did not differ but mean seminal oestradiol was significantly increased. Of the infertile men, 53% had seminal oestradiol concentration above the 90th percentile value for fertile men. The meaning of this seminal oestradiol increase is unclear since it is not known whether it is the cause or the consequence of the alteration of spermatogenesis in infertile men. Further studies are required to explore the possible therapeutic implications. [ABSTRACT FROM AUTHOR]

- Testicular volume was assessed in 1029 infertile men and found to be normal in 704; 71 patients had unilateral and 213 had bilateral testicular hypotrophy; 4 had unilateral and 37 had bilateral atrophy. Sperm count and motility decreased in accordance with testicular volume. The lowest mean sperm counts and lowest mean motility percentages were found in patients with bilateral testicular atrophy. An increase in mean FSH and LH was also significantly linked to decreasing testicular volume; the increase in the former was not related to a drop in sperm count. A significant correlation was found between testicular volume and spermatogenesis and testicular volume is considered to be a reliable indicator of testicular function. [ABSTRACT FROM AUTHOR]

Several recent studies have reported a gradual decline in sperm production in men. Endocrine disrupters as well as lifestyle have been suggested as risk factors. One lifestyle factor that may affect human fertility is driving a vehicle for a prolonged period. Several authors have suggested that driving position may increase the scrotal temperature. In order to validate this hypothesis we conducted continuous monitoring of scrotal temperature in real conditions, i.e. in men driving a car for a prolonged period. Nine volunteer men were asked to walk outside for 40 min and then to drive a car for 160 min. Scrotal temperatures were measured from thermocouples and values recorded every 2 min on a portable data recorder. Scrotal temperature increased significantly (P < 0.0001) in driving posture after 2 h of driving, reaching a value 1.7-2.2 degrees C higher than that recorded while walking. This link between driving position and increased scrotal temperature indicates a potential exposure of male reproductive function to lifestyle factors. [ABSTRACT FROM AUTHOR]

Background: Two male contraceptive methods that inhibit spermatogenesis currently exist: thermal male contraception and hormonal male contraception. Only five studies have been conducted on the acceptability of these methods among men; among women, only the hypothetical acceptability of such a male contraceptive approach as the sole contraception method used by a couple has been evaluated., Objectives: To evaluate the motivation, experience, and satisfaction of female partners in couples using hormonal male contraception or thermal male contraception as the sole contraception., Materials and Methods: In this cross-sectional study, 123 male users of hormonal male contraception or thermal male contraception as the couple's sole contraception method were asked to invite their female partner to participate in an anonymous online survey. The questionnaire included 95 questions exploring population characteristics, contraceptive and pregnancy history, motivations for choosing hormonal male contraception or thermal male contraception, the experience of the women in the successive phase of use, relationships with their partner, and satisfaction with the contraception method., Results: The response rate among participating women was 69% (59/86). The two main reasons for choosing male contraceptive were the desire to share the contraception role in the couple (65%) and the desire of the man to take charge of the contraception (61%). The sexual satisfaction score increased significantly between the contraceptive methods used before hormonal male contraception or thermal male contraception and the phase of contraceptive use (p < 0.01). The overall satisfaction level with thermal male contraception or hormonal male contraception was rated at 3.7 ± 0.6 out of 4. Women mostly recommended hormonal male contraception or thermal male contraception because of the share of contraceptive responsibility and mental load (n = 23/54, 43%)., Discussion: This population of women seemed to have struggled to find a contraceptive method that suited them, but most took advantage of thermal male contraception or hormonal male contraception and trusted their male partner to take charge of contraception use., Conclusion: The positive evaluation from women in partnerships using thermal male contraception and hormonal male contraception should encourage the development of these methods., (© 2024 The Author(s). Andrology published by John Wiley & Sons Ltd on behalf of American Society of Andrology and European Academy of Andrology.)

Purpose: The aim of this study is to evaluate the motivations, experience, and acceptability of thermal male contraception (TMC) in male partners of couples requesting the use of TMC as the only couple contraceptive., Materials and Methods: To the 72 men of couples seeking male contraception and using TMC between 2011 and 2019, we suggested an anonymous online survey (93 questions) exploring population characteristics, contraceptive histories, motivations for choosing TMC, patient experience at the successive phases of use, relations with partner and environment, and satisfaction with this method., Results: Sixty-seven men agreed to participate (93% response rate); 63 responses were complete and were analyzed (94% participation rate). The main motivations for choosing TMC were "not using hormones" (n = 59/63, 94%) and using a method regarded as "natural" (n = 49/63, 78%). Most of the men surveyed (68%) adopted the method in less than 2 weeks. During the contraception use phase (n = 59 men), they described significantly improved sexual satisfaction, compared to that experienced with their previous contraceptive methods, and they reported high confidence (100% rather/totally confident partner) and support (88% rather/totally supporting partner) from their partner. Most men (n = 35/59, 59%) also reported improved self-esteem. The main negative point was discomfort, reported by 24% of the men. The overall satisfaction score of using this method was 3.78 ± 0.46/4, and 100% of the men reported that they would recommend the method to other men., Discussion and Conclusion: Men using TMC successfully assumed the responsibility for and performed a daily task to provide couple contraception. This positive evaluation, together with the already published contraceptive efficacy and reversibility of TMC, should encourage the development of this method., (© 2022 American Society of Andrology and European Academy of Andrology.)

Objectives: Health professionals are at the forefront of information and acceptability regarding contraceptive methods, however only one study evaluated their knowledge of male contraception (MC) including hormonal MC (HMC) and thermal MC (TMC). Our objective was to evaluate the knowledge, professional attitudes, and training of French practitioners regarding the management of couple contraception by male contraception (MC)., Study Design: We designed a descriptive, cross-sectional, multicentre study in 2,396 French practitioners belonging to national or regional institutions involved in contraception. We solicited practitioners by e-mail to complete an anonymous questionnaire; we analysed their knowledge, professional attitudes, and training regarding the management of couple contraception by MC., Results: The overall participation rate was 18% (427/2,396). Condoms, withdrawal, and vasectomy were known by 98%, 89%, and 76% of the population, respectively. Hormonal MC and Thermal (TMC) were known by 10% and 24% of the population, respectively. Fifty-five percent of the population never or infrequently offered MC during a couple's contraceptive request consultation. Only 14% of the population had ever participated in training on MC; 96% wanted to be better trained on MC, and 87% expressed a willingness to participate in training on the subject., Conclusions: Health professionals involved in contraception have unsatisfactory knowledge about MC methods based on spermatogenesis inhibition and are eager to have more information about them. To advance the acceptability and dissemination of MC methods, it seems imperative to enhance research in the field and to provide health professionals with an adapted training programme.

Background: Congenital unilateral absence of vas deferens has been diagnosed in fertile and normozoospermic males and is associated with the risk of unilateral renal absence or cystic fibrosis transmembrane conductance regulator mutations; but no prediction model currently exists to diagnose this condition., Objectives: The study aims to identify clinical and biological variables that may have a predictive value for the diagnosis of congenital unilateral absence of vas deferens in male partners of infertile couples MATERIALS AND METHODS: We designed a retrospective, cross-sectional, case-control study on electronic health records of a single tertiary-care andrological centre collected between 1998 and 2018. We included all subjects diagnosed with congenital unilateral absence of vas deferens using combined scrotal and transrectal ultrasounds. Controls were confirmed free of congenital unilateral absence of vas deferens by the same way. Both groups received standardised exploration procedures. Multivariable logistic regression model was built in a backward stepwise manner. Model performance and calibration were assessed. The study is reported according to TRIPOD statement., Results: We included 69 congenital unilateral absence of vas deferens cases and 78 controls. Cases had a lower semen volume than controls. The congenital unilateral absence of vas deferens risk was associated with history of cryptorchidism and both levels of semen fructose and α-glucosidase. These predictors were confirmed by a random forest algorithm. The area under the curve was 0.886 (95% interval: 0.81-0.92). Calibration was performed with the Hosmer-Lemeshow test (p = 0.88)., Discussion and Conclusion: History of cryptorchidism, semen fructose and α-glucosidase were identified as relevant and independent predictors for the diagnosis of congenital unilateral absence of vas deferens. The model enables to identify male patients with a high risk of congenital unilateral absence of vas deferens to whom a transrectal ultrasounds would be proposed to confirm the diagnosis, whatever their semen parameters. It will also help to address the risks of unilateral renal absence and of cystic fibrosis transmembrane conductance regulator mutations carrying during the management of infertile couples., (© 2021 American Society of Andrology and European Academy of Andrology.)

Congenital absence of the vas deferens (CAVD) may have various clinical presentations depending on whether it is bilateral (CBAVD) or unilateral (CUAVD), complete or partial, and associated or not with other abnormalities of the male urogenital tract. CBAVD is usually discovered in adult men either during the systematic assessment of cystic fibrosis or other CFTR-related conditions, or during the exploration of isolated infertility with obstructive azoospermia. The prevalence of CAVDs in men is reported to be approximately 0.1%. However, this figure is probably underestimated, because unilateral forms of CAVD in asymptomatic fertile men are not usually diagnosed. The diagnosis of CAVDs is based on clinical, ultrasound, and sperm examinations. The majority of subjects with CAVD carry at least one cystic fibrosis-causing mutation that warrants CFTR testing and in case of a positive result, genetic counseling prior to conception. Approximately 2% of the cases of CAVD are hemizygous for a loss-of-function mutation in the ADGRG2 gene that may cause a familial form of X-linked infertility. However, despite this recent finding, 10-20% of CBAVDs and 60-70% of CUAVDs remain without a genetic diagnosis. An important proportion of these unexplained CAVDs coexist with a solitary kidney suggesting an early organogenesis disorder (Wolffian duct), unlike CAVDs related to CFTR or ADGRG2 mutations, which might be the result of progressive degeneration that begins later in fetal life and probably continues after birth. How the dysfunction of CFTR, ADGRG2, or other genes such as SLC29A3 leads to this involution is the subject of various pathophysiological hypotheses that are discussed in this review.

Background: Men with congenital unilateral absence of vas deferens were reported to be mainly azoospermic, with both unilateral renal absence and mutations in the cystic fibrosis transmembrane conductance regulator (CFTR) but some have neither., Objectives: To assess whether in infertile couples the male partners with congenital unilateral absence of vas deferens are mainly azoospermic men., Material and Methods: Retrospective study in a unique university hospital; reproductive, clinical, CFTR analysis and seminal data of male partners of infertile couples (from 1998 to 2018) were analysed. Diagnosis of congenital unilateral absence of vas deferens was based on transrectal ultrasounds (TRUS): complete or partial absence of one vas deferens with complete contralateral vas deferens confirmed in 63 men. Distribution of sperm count in three classes: azoospermia, oligozoospermia or normozoospermia. Ultrasound determination of renal status; seminal biomarkers assays; and search for CFTR mutations., Results: Among the 63 men, 39.7% displayed azoospermia, 27% oligozoospermia and 33.3% normozoospermia; 42% of the non-azoospermic men (16/38) had previously obtained a natural pregnancy. We found unilateral renal absence in 17/59 patients (29%). Among 50 men with CFTR testing, five carried an allele associated with cystic fibrosis belonging to the 29 men without renal anomalies, indicating a high allelic frequency (8.6%). The 63 patients displayed high rates of surgical histories for undescended testicles or inguinal hernia, low values of semen volume and of total seminal glycerophosphocholine., Conclusions: Our results indicate that men with congenital unilateral absence of vas deferens mainly display oligozoospermia or normozoospermia and that they were previously fertile. They clearly confirm, first, that CFTR testing is recommended in congenital unilateral absence of vas deferens men and it should be mandatory for those with normal kidneys; and, second, that TRUS is needed for the diagnosis of congenital unilateral absence of vas deferens. As congenital unilateral absence of vas deferens may be present whatever the sperm count, biological warnings are represented by semen volume and seminal epididymal markers and clinical warnings by surgical histories of undescended testes or inguinal hernia., (© 2019 American Society of Andrology and European Academy of Andrology.)

Background: A mild increase in testicular and epididymal temperatures in men, bulls and rams (pendulous scrotum) inhibits spermatogenesis and increases the percentage of sperm with an abnormal morphology. However, the stages of spermatogenesis that are most sensitive to a mild increase in testicular temperature in men are unknown. The aim of the present study was to explore the effects of a mild induced increase in testicular and epididymal temperature (i.e., testicular temperature maintained below the core body temperature) on sperm morphology in humans depending on the physiological time of spermatogenesis and epididymal transit., Methods: Five healthy volunteers were enrolled in an experimental study in which testicular and epididymal temperatures were increased by maintaining the testes in a supra-scrotal position with a specially designed underwear worn 15±1 h a day for 120 consecutive days. Semen collection was scheduled on specific days depending on spermatogenic stages and epididymal transit., Results: Sperm morphology and the multiple anomalies index (MAI) were analysed before, during and after heating. This mild induced increase in testicular and epididymal temperatures resulted in a significant rise in the percentage of morphologically abnormal spermatozoa on day 34 of heating, which remained elevated throughout the heating period and persisted until 45 days after cessation of heating. The MAI was significantly increased on day 20 throughout the heating period and persisted 45 days after cessation of heating. An increase in the percentage of anomalies in the sperm head, acrosome or tail occurred on days 34 and/or 45 of heating. Abnormal sperm morphology and MAI reverted to control values 73 days after cessation of heating., Conclusions: A mild sustained increase in testicular and epididymal temperature in man leads morphological abnormalities in spermatozoa mainly due to an impairment of spermiogenesis and meiosis., Competing Interests: Conflicts of Interest: The authors have no conflicts of interest to declare., (2019 Translational Andrology and Urology. All rights reserved.)