Second chance in fertility: a comprehensive narrative review of redo micro-TESE outcomes after initial failure

When microdissection testicular sperm extraction (micro-TESE) fails, a redo procedure may be the only option for patients who want a biological child. However, there are many gaps of knowledge surrounding the procedure, which need to be addressed to help clinicians and patients make informed decisions. This review explores redo micro-TESE in the context of nonobstructive azoospermia (NOA). Literature was searched using Google Scholar, Medline, and PubMed. Search terms were "NOA" AND "second microdissection testicular sperm extractions" AND "redo microdissection testicles sperm extraction" AND "repeat microdissection testicular sperm extractions" AND "failed microdissection testicular sperm extractions" AND "salvage microdissection testicular sperm extractions". Only original articles in English were included. A total of nine articles were included, consisting of four retrospective and five prospective studies. The time gap between the first and second micro-TESE varied from 6 months to 24 months. Most of the included studies reported successful surgical sperm retrieval (SSR) in the second micro-TESE in the range of 10%-21%, except in one study where it reached 42%. It has not been presented any definitive information about the use of hormonal treatment or the benefit of varicocelectomy prior to the second micro-TESE. Patients with hypospermatogenesis and Klinefelter syndrome (KS) had the highest chance of success in redo surgery. In conclusion, redo micro-TESE following a negative procedure can lead to sperm recovery in 10%-21%. Patients with hypospermatogenesis and KS have a higher chance of success. There is no enough evidence to conclude which is the best hormonal stimulation if any before a redo surgery.

Clinical management of nonobstructive azoospermia: An update

Approximately 1% of the general male population has azoospermia, and nonobstructive azoospermia accounts for the majority of cases. The causes vary widely, including chromosomal and genetic abnormalities, varicocele, drug-induced causes, and gonadotropin deficiency; however, the cause is often unknown. In azoospermia caused by hypogonadotropic hypogonadism, gonadotropin replacement therapy can be expected to produce sperm in the ejaculate. In some cases, upfront varicocelectomy for nonobstructive azoospermia with varicocele may result in the appearance of ejaculated spermatozoa; however, the appropriate indication should be selected. Each guideline recommends microdissection testicular sperm extraction for nonobstructive azoospermia in terms of successful sperm retrieval and avoidance of complications. Sperm retrieval rates generally ranged from 20% to 70% but vary depending on the causative disease. Various attempts have been made to predict sperm retrieval and improve sperm retrieval rates; however, the evidence is insufficient. Further evidence accumulation is needed for salvage treatment in cases of failed sperm retrieval. In Japan, there is inadequate provision on the right to know the origin of children born from artificial insemination of donated sperm and the rights of sperm donors, as well as information on unrelated family members, and the development of these systems is challenging. In the future, it is hoped that the pathogenesis of nonobstructive azoospermia with an unknown cause will be elucidated and that technology for omics technologies, human spermatogenesis using pluripotent cells, and organ culture methods will be developed.

[Medical treatments for male infertility]

BACKGROUND

Treatments to stimulate spermatogenesis and antioxidant food supplements are often offered to infertile patients either before sperm extraction surgery to improve results, or as part of medically assisted reproduction or spontaneous fertility to increase the likelihood of a live birth.

METHODS

A bibliographic search limited to English-language literature on men published before 5/2023 was carried out, including clinical trials, literature reviews and meta-analyses on spermatogenesis-stimulating molecules and antioxidant treatments.

RESULTS

Several medical treatments seem capable of improving male fertility: they act mainly by stimulating spermatogenesis through hormones, or by reducing the effects of oxidative stress. With regard to oligoasthenozoospermia, the literature shows that certain hormonal treatments stimulating spermatogenesis are useful. In the case of non-obstructive azoospermia, the value of treatment depends on the patient's FSH and testosterone levels. AOX supplementation appears to improve certain spermogram parameters and have an impact on pregnancy and live birth rates.

CONCLUSION

This review should help urologists gain a better understanding of the various medical treatments and enable them to define an appropriate therapeutic strategy, tailored to the patient and the couple, in order to obtain the best results.

The use of hormone stimulation in male infertility

Infertility affects 15% of couples worldwide and in approximately 50% of cases the cause is secondary to an abnormality of the sperm. However, treatment options for male infertility are limited and empirical use of hormone stimulation has been utilised. We review the contemporary data regarding the application of hormone stimulation to treat male infertility. There is strong evidence supporting the use of hormone stimulation in hypogonadotropic hypogonadism but there is inadequate evidence for all other indications.

Male infertility and gonadotropin treatment: What can we learn from real-world data?

Gonadotropin therapy to treat specific male infertility disorders associated with hypogonadotropic hypogonadism is evidence-based and effective in restoring spermatogenesis and fertility. In contrast, its use to improve fertility in men with idiopathic oligozoospermia or nonobstructive azoospermia remains controversial, despite being widely practiced. The existence of two major inter-related pathways for spermatogenesis, including FSH and intratesticular testosterone, provides a rationale for empiric hormone stimulation therapy in both eugonadal and hypogonadal males with idiopathic oligozoospermia or nonobstructive azoospermia. Real-world data (RWD) on gonadotropin stimulating for these patient subsets, mainly using human chorionic gonadotropin and follicle-stimulating hormone, accumulated gradually, showing a positive therapeutic effect in some patients, translated by increased sperm production, sperm quality, and sperm retrieval rates. Although more evidence is needed, current insights from RWD research indicate that selected male infertility patients might be managed more effectively using gonadotropin therapy, with potential gains for all parties involved.

Recombinant gonadotropin therapy to improve spermatogenesis in nonobstructive azoospermic patients – A proof of concept study

Purpose:

Nonobstructive azoospermia (NOA) associated with primary spermatogenic failure is a common cause of male infertility usually considered untreatable; however, some reports have suggested that hormonal stimulation to boost the intra-testicular testosterone level and spermatogenesis might increase the chance of achieving pregnancy using homologous sperm.

Materials and Methods:

We report a series of eight NOA males who received long-term treatment with recombinant human chorionic gonadotropin twice a week for spermatogenesis stimulation. Six males received additional recombinant follicle-stimulating hormone (FSH) supplementation 150-225 IU twice weekly.

Results:

After recombinant gonadotropin therapy, viable spermatozoa were retrieved from the ejaculate in two patients and by testicular sperm aspiration (TESA) in another two subjects. Singleton spermatozoon retrieved from testes were frozen by vitrification on Cell-Sleeper devices. Two live births were obtained after intracytoplasmic sperm injection with ejaculated spermatozoa and one live birth and an ongoing pregnancy using thawed spermatozoa from TESA.

Conclusion:

Our proof-of-concept study indicates that hormonal therapy with recombinant gonadotropins could be considered in infertile men with NOA as an alternative to sperm donation. Large-scale studies are needed to substantiate hormone stimulation therapy with recombinant gonadotropins in routine clinical practice for this severe form of male infertility.

Recombinant gonadotropin therapy to improve spermatogenesis in nonobstructive azoospermic patients - A proof of concept study

PURPOSE

Nonobstructive azoospermia (NOA) associated with primary spermatogenic failure is a common cause of male infertility usually considered untreatable; however, some reports have suggested that hormonal stimulation to boost the intra-testicular testosterone level and spermatogenesis might increase the chance of achieving pregnancy using homologous sperm.

MATERIALS AND METHODS

We report a series of eight NOA males who received long-term treatment with recombinant human chorionic gonadotropin twice a week for spermatogenesis stimulation. Six males received additional recombinant follicle-stimulating hormone (FSH) supplementation 150-225 IU twice weekly.

RESULTS

After recombinant gonadotropin therapy, viable spermatozoa were retrieved from the ejaculate in two patients and by testicular sperm aspiration (TESA) in another two subjects. Singleton spermatozoon retrieved from testes were frozen by vitrification on Cell-Sleeper devices. Two live births were obtained after intracytoplasmic sperm injection with ejaculated spermatozoa and one live birth and an ongoing pregnancy using thawed spermatozoa from TESA.

CONCLUSION

Our proof-of-concept study indicates that hormonal therapy with recombinant gonadotropins could be considered in infertile men with NOA as an alternative to sperm donation. Large-scale studies are needed to substantiate hormone stimulation therapy with recombinant gonadotropins in routine clinical practice for this severe form of male infertility.

Gonadotropins treatment prior to microdissection testicular sperm extraction in non-obstructive azoospermia: a single-center cohort study

BACKGROUND

Microdissection testicular sperm extraction (micro-TESE) in combination with ICSI can make paternity possible for non-obstructive azoospermia (NOA) patients. Testicular sperm can be successfully retrieved in nearly half of NOA patients. Nevertheless, not many convincing protocols are established to improve sperm retrieval rate (SRR). The goal of this study was to evaluate whether gonadotropins therapy before micro-TESE could improve sperm retrieval rate and affect the ICSI outcomes in non-obstructive azoospermia patients with hypergonadotropic hypogonadism.

METHODS

This retrospective cohort study included a total of 569 non-obstructive azoospermia men who underwent micro-TESE with or without 3-month of preoperative hCG / hCG plus highly purified urinary FSH (uFSH) between January 2016 and December 2019. The primary outcome was the sperm retrieval rate of micro-TESE.

RESULTS

Sperm was found in 27 patients among 395 NOA men who accepted preoperative gonadotropins treatment (6.8%, 27/395) in post-treatment semen analysis for ICSI. One hundred forty nine out of 542 patients could successfully obtain enough sperm for ICSI through the micro-TESE (overall SRR = 27.5%). There was a statistically significant difference in the SRR between the preoperative gonadotropins treatment and non-gonadotropins treatment groups (31.2%, 115/368 vs. 19.5%, 34/174, P = 0.006). In the multivariable analysis with IPTW according to the propensity score, there was a significant association between preoperative gonadotropins treatment and the SRR (OR, 1.59; 95% CI: 1.02-2.52; P = 0.042). No differences in the clinical pregnancy rate, live birth delivery rate, or miscarriage rate were observed between the two groups.

CONCLUSION

Preoperative gonadotropins therapy seems to have a role in improving SRR in NOA patients with hypergonadotropic hypogonadism. We found that gonadotropins therapy had no effect on ICSI clinical outcomes and live birth.

OUP accepted manuscript

BACKGROUND

The beneficial effects of hormonal therapy in stimulating spermatogenesis in patients with non-obstructive azoospermia (NOA) and either normal gonadotrophins or hypergonadotropic hypogonadism prior to surgical sperm retrieval (SSR) is controversial. Although the European Association of Urology guidelines state that hormone stimulation is not recommended in routine clinical practice, a significant number of patients undergo empiric therapy prior to SSR. The success rate for SSR from microdissection testicular sperm extraction is only 40–60%, thus hormonal therapy could prove to be an effective adjunctive therapy to increase SSR rates.

OBJECTIVE AND RATIONALE

The primary aim of this systematic review and meta-analysis was to compare the SSR rates in men with NOA (excluding those with hypogonadotropic hypogonadism) receiving hormone therapy compared to placebo or no treatment. The secondary objective was to compare the effects of hormonal therapy in normogonadotropic and hypergonadotropic NOA men.

SEARCH METHODS

A literature search was performed using the Medline, Embase, Web of Science and Clinicaltrials.gov databases from 01 January 1946 to 17 September 2020. We included all studies where hormone status was confirmed. We excluded non-English language and animal studies. Heterogeneity was calculated using I² statistics and risk of bias was assessed using Cochrane tools. We performed a meta-analysis on all the eligible controlled trials to determine whether hormone stimulation (irrespective of class) improved SSR rates and also whether this was affected by baseline hormone status (hypergonadotropic versus normogonadotropic NOA men). Sensitivity analyses were performed when indicated.

OUTCOMES

A total of 3846 studies were screened and 22 studies were included with 1706 participants. A higher SSR rate in subjects pre-treated with hormonal therapy was observed (odds ratio (OR) 1.96, 95% CI: 1.08–3.56, P = 0.03) and this trend persisted when excluding a study containing only men with Klinefelter syndrome (OR 1.90, 95% CI: 1.03–3.51, P = 0.04). However, the subgroup analysis of baseline hormone status demonstrated a significant improvement only in normogonadotropic men (OR 2.13, 95% CI: 1.10–4.14, P = 0.02) and not in hypergonadotropic patients (OR 1.73, 95% CI: 0.44–6.77, P = 0.43). The literature was at moderate or severe risk of bias.

WIDER IMPLICATIONS

This meta-analysis demonstrates that hormone therapy is not associated with improved SSR rates in hypergonadotropic hypogonadism. While hormone therapy improved SSR rates in eugonadal men with NOA, the quality of evidence was low with a moderate to high risk of bias. Therefore, hormone therapy should not be routinely used in men with NOA prior to SSR and large scale, prospective randomized controlled trials are needed to validate the meta-analysis findings.

Intrasurgical parameters associated with successful sperm retrieval in patients with non-obstructive azoospermia undergoing salvage microdissection testicular sperm extraction

BACKGROUND

Patients with non-obstructive azoospermia with a previously failed conventional testicular sperm extraction may undergo a salvage microdissection testicular sperm extraction with the probability of successful sperm retrieval being almost dependent upon the number of previous surgical attempts and to different histopathologic categories.

OBJECTIVES

To determine whether the seminiferous tubules pattern and the histological categories could affect the sperm retrieval rate in patients with non-obstructive azoospermia undergoing salvage microdissection testicular sperm extraction after failed conventional testicular sperm extraction.

MATERIALS AND METHODS

Seventy-nine patients undergoing unilateral or bilateral salvage microdissection testicular sperm extraction were evaluated. During microdissection testicular sperm extraction, if present, dilated tubules were retrieved, otherwise, tubules with slightly larger caliber than that of the surroundings were removed. When no dilated tubule or tubule with slightly larger caliber was found, not dilated tubules were excised. A prediction model was built with seminiferous tubules pattern and testis histology as covariates.

RESULTS

Sperm retrieval was successful in 30 out of 79 patients. The prediction model correctly classified 88.3% of cases, explained the 29.7% variability of the outcome, and significantly predicted the microdissection testicular sperm extraction outcome with a sensitivity of 67.7% and a specificity of 90.2%, Both tubules with slightly larger caliber and not dilated tubules were negatively associated with the chance of retrieving spermatozoa. Among the histological categories, only early maturation arrest was significant to the model (log(SSR) = 0.57 - 1.9SDT - 3.3NDT - 1.76EMA) (where SSR is sperm retrieval rate, SDT is tubule with slightly larger caliber, NDT is not dilated tubule, and EMA is early maturation arrest). The model had a clearly useful discrimination (area under the curve = 0.814), the estimated performance was 0.8105, and internal calibration was acceptable (p > 0.05).

DISCUSSION

Seminiferous tubules pattern and testis histology may reliably explain the salvage microdissection testicular sperm extraction outcome in all patients with non-obstructive azoospermia apart from those with early maturation arrest, where the homogeneous apparent seminiferous tubules pattern may be misleading.

CONCLUSION

The outcome of salvage microdissection testicular sperm extraction can be predicted by the same intrasurgical parameters that have been demonstrated to predict the outcome of microdissection testicular sperm extraction in naïve patients with non-obstructive azoospermia.

Efficacy of the second micro-testicular sperm extraction after failed first micro-testicular sperm extraction in men with nonobstructive azoospermia

OBJECTIVE

To evaluate the efficacy of the second micro-testicular sperm extraction (TESE)in men with nonobstructive azoospermia in whom the first micro-TESE failed.

DESIGN

Retrospective.

SETTING

Private clinic.

PATIENT(S)

One hundred twenty-five men with nonobstructive azoospermia with failed previous micro-TESE. The patients were divided into 2 groups according to their surgical sperm retrieval status during the second micro-TESE. If sperm could not be found, these patients were classified as Group 1, and, if sperm was found, the patients were classified as Group 2. The 2 groups were compared for clinical parameters and pathologic findings.

INTERVENTION(S)

Micro-TESE.

MAIN OUTCOME MEASURE(S)

Surgical sperm retrieval status.

RESULT(S)

Sperm was recovered successfully in 23 of 125 (18.4%) men with the second micro-TESE. Testicular volume was significantly lower in Group 2 (8.2 ± 5.4 mL) than Group 1 (11.3 ± 5.3 mL). Seven of 14 (50%) patients with Klinefelter's Syndrome had sperm recovery with repeat micro-TESE. The sperm retrieval rate was significantly higher in the Leydig cell hyperplasia and tubular sclerosis groups than in the Sertoli cell only and maturation arrest groups (54.5%, 10.1%, and 18.6%, respectively).

CONCLUSION(S)

On the basis of our results, 18.4% of men with failed first micro-TESE had a probability of sperm retrieval with the second micro-TESE. Patients with successful sperm recovery had smaller testicular volumes than those with a failed second attempt. Severe testicular atrophy was not a contraindication for the second micro-TESE in such patients.

Evaluation of neoadjuvant gonadotropin administration with downregulation by testosterone prior to second time microsurgical testicular sperm extraction: A prospective case-control study

PURPOSE

The aim of this prospective study was to determine whether there is a beneficial role of combining gonadotropin administration with testosterone downregulation in non-obstructive azoospermia patients prior to a second time microsurgical testicular sperm extraction after a negative one.

METHODS

A total of 40 non-obstructive azoospermia men were recruited from a specialized IVF center from 2014 to 2016. Participants were divided equally into two groups: Group A was subjected to testosterone downregulation alone for 1 month and then combined with gonadotropin administration for 3 months prior to second time testicular sperm extraction; Group B (controls) underwent second time microsurgical testicular sperm extraction without prior hormonal therapy.

RESULTS

Mean baseline follicle-stimulating hormone levels of the controls and the cases were 26.9 ± 11.8 and 25.4 ± 8.7, respectively. One month after testosterone downregulation, follicle-stimulating hormone level of the cases was normalized and became 2.4 ± 1.2. There was no statistically significant difference between baseline follicle-stimulating hormone levels of the controls and cases (p = 0.946). Remarkably, two cases were positive after downregulation (10%) and no controls were positive at second testicular sperm extraction (0%). There was no statistically significant difference between sperm retrieval after the second microsurgical testicular sperm extraction in the controls and the cases (p = 0.072).

CONCLUSION

Patients who underwent first time testicular sperm extraction with unfavorable outcome due to different techniques may benefit from testosterone downregulation combined with neoadjuvant gonadotropin administration as it had shown positive sperms retrieval in 2 out of the 20 cases, especially those with hypergonadotropic azoospermia.

Microdissection testicular sperm extraction: preoperative patient optimization, surgical technique, and tissue processing

Infertility due to nonobstructive azoospermia is treatable with the use of testicular sperm extraction and IVF. The optimal approach for sperm retrieval is microdissection testicular sperm extraction (mTESE). This systematic review summarizes and evaluates the literature pertaining to patient optimization before mTESE, mTESE technique, and post-mTESE testicular tissue processing. Preoperative patient optimization has been assessed in terms of adjuvant hormone therapy and varicocele repair. Limited data are available for adjuvant medical therapy, and although also limited, data for varicocele repair support increased sperm retrieval, pregnancy, and return of sperm to the ejaculate. Post-mTESE tissue processing has few comparative studies; however, most studies support the combination of mechanical mincing and use of type 4 collagenase for tissue disintegration along with pentoxifylline to assist in identifying motile and viable spermatozoa for intracytoplasmic sperm injection.

Spermatogenesis improved by suppressing the high level of endogenous gonadotropins in idiopathic non-obstructive azoospermia: a case control pilot study

BACKGROUND

Elevated plasma gonadotropins were associated with desensitization of Sertoli and Leydig cells in the male testis. Testis spermatogenesis ability would be improved via inhibiting high endogenous gonadotropin in patients with severe oligozoospermia. Whether it would be beneficial for non-obstructive azoospermia (NOA) patients was still unclear.

METHODS

Goserelin, a gonadotropin releasing hormone agonist (GnRHα) was used to suppress endogenous gonadotropin levels (gonadotropin reset) in the NOA patients, improving the sensitization of the Sertoli and Leydig cells. Then human menopausal gonadotropin (hMG) and human chorionic gonadotropin (hCG) were injected to stimulate them to ameliorate the ability of testicular spermatogenesis. The main outcome measure was the existence of spermatozoa in the semen or by testicular sperm extraction (TESE). Elevation of inhibin B and/or ameliorative expression pattern of ZO-1 was the secondary objective.

RESULTS

A total of 35 NOA men who failed to retrieve sperm via TESE were enrolled. Among these, 10 patients without treatment were selected as control group and secondary TESE was performed 6 months later. Of the 25 treated men, inhibin B was elevated in 11 patients in the first 4 weeks (Response group), while only 5 patients had constant increase in the following 20 weeks (Response group 2). Of the 5 men, 2 men acquired sperm (Response group 2B), while 3 failed (Response group 2A). Immunofluorescence of mouse vasa homologue (MVH) and ZO-1 showed that both positive MVH signals and ZO-1 expression were significantly increased in the Response group 2, but only Response group 2B showed ameliorative ZO-1 distribution.

CONCLUSIONS

Gonadotropin reset, a new therapeutic protocol with GnRHα, was able to improve the ability of testicular spermatogenesis in the NOA patients through restoring the sensitivity of Sertoli and Leydig cells, which were reflected by elevated inhibin B and ameliorative ZO-1 expression and distribution.

TRIAL REGISTRATION

ClinicalTrials.gov identifier: NCT02544191 .

ADAMTS1 and ADAMTS5 metalloproteases produced by Sertoli cells: a potential diagnostic marker in azoospermia

In this study, our aim was to detect protein levels of A Disintegrin and Metalloproteinase with Thrombospondin Motifs 1 and 5 (ADAMTS1 and ADAMTS5) proteases and to examine the effect of in vitro FSH supplementation on protease production in cultured Sertoli cells. The expression of metalloproteases, ADAMTS1, and ADAMTS5 were investigated in Sertoli cell cultures as well as in ejaculate of azoospermic men which then were compared with ejaculates of the fertile control group. A total of 15 azoospermic men, diagnosed as obstructive (OA, n = 5) and nonobstructive (NOA, n = 10) azoospermia were included in the study. ADAMTS1, ADAMTS5 and FSH receptors (FSHR) were found to be expressed 2.56, 2.10, and 2.66-fold less in Sertoli cells of NOA patients, than those of OA (p < 0.05). After rFSH was added onto Sertoli cell cultures of NOA patients, their expression did not increase significantly and did not reach to levels of control group. Evaluation of ejaculates revealed that the expression of ADAMTS1 and ADAMTS5 were insignificantly 1.03 and 1.1-fold higher in OA group (p > 0.05), respectively; however, in the NOA group, their expression were 1.70 and 1.96-fold lower, respectively, when compared with the fertile control group (p < 0.05) which was statistically significant. As a conclusion, the present study has revealed that insufficiency of ADAMTS1 and ADAMTS5 expression in Sertoli cells may have an important role in the etiology of male infertility. As expected due to low FSHR expression, rFSH response is impaired in NOA patients with relatively low ADAMTS expression response; therefore, such patients might hardly benefit from rFSH treatment. Further studies with larger cohorts may reveal ADAMTSs' potential use as a predictive marker for positive sperm retrieval in azoospermic patients who are scheduled to undergo testicular sperm extraction. Abbreviations: ADAM: A Disintegrin and Metalloproteinase; ADAMTS1 and ADAMTS5: A Disintegrin and Metalloproteinase with 10 Thrombospondin Motifs 1 and 5; ADAMTS: A Disintegrin and Metalloproteinase with Thrombospondin; ABP: androgen binding protein; CAMs: cell adhesion molecules; ECM: extracellular matrix; FSH: follicle stimulating hormone; FSHR: FSH receptors; HRP: horseradish peroxidase; MMP: matrix metalloproteinases; MP: metalloproteinases; NOA: nonobstructive azoospermia; OA: obstructive azoospermia; TIMP-1: tissue inhibitor of metalloproteinase-1.

Gonadotoropin actions on spermatogenesis and hormonal therapies for spermatogenic disorders [Review]

Microdissection testicular sperm extraction and intracytoplasmic sperm injection have made it possible for men with non-obstructive azoospermia (NOA) to conceive a child. A majority of men cannot produce sperm because spermatogenesis per se is believed to be "irreversibly" disturbed. For these men, it has been thought that any hormonal therapy will be ineffective. Further understandings of endocrinological regulation of spermatogenesis are needed and LH or FSH receptor knock out (KO) mice have revealed the roles of gonadotropin separately. Spermatogenesis has been shown to shift during evolution from FSH to LH dominance because LH receptor KO causes infertility while FSH receptor KO does not. High concentrations of intratesticular testosterone secreted from Leydig cells, ranging from 100- to 1,000-fold higher than in the systemic circulation, has pivotal roles during spermatogenesis. This is especially important during spermiogenesis, a post-meiotic step for progression from round to elongating spermatids. Sertoli cells are the target of FSH and have numerous androgen receptors, indicating that Sertoli cells are regulated by FSH and the paracrine functions of testosterone. In combination with Leydig cell-derived growth factors, particularly epidermal growth factor-like growth factors, Sertoli cells support spermatogenesis, especially at proximal levels of spermatogenesis (e.g., spermatogonial proliferation). Taken together, the current knowledge from human studies indicating that testosterone optimization by clomiphene, hCG and/or aromatase inhibitors and high dose hCG/FSH treatment can, at least in part, improve spermatogenesis in NOA. Accordingly hormonal therapy may open a therapeutic window for sperm production in selected patients.