Relationship between male aging and semen quality: a retrospective study on over 2500 men.

PURPOSE: We aimed to evaluate whether and to what extent an association exists between male aging and worsening of semen parameters and to determine whether a threshold age can be identified above which the decline in semen quality becomes statistically significant. METHODS: 2612 men (age: 16-56 years) attending an andrology outpatient clinic for semen analysis and clinical evaluation were studied. Semen analyses were performed according to the ongoing WHO-recommended procedures. Total motile count (TMC) and total progressive motile count (TPMC) were calculated by multiplying total sperm number by total motility and progressive motility, respectively. RESULTS: Significant negative correlations were found between age and total motility (r = - 0.131, p < 0.0001), progressive motility (r = - 0.112, p < 0.0001), TPMC (r = - 0.042, p = 0.037), and normal sperm morphology (r = - 0.053, p = 0.007). All these associations persisted in multivariate regression models adjusted for abstinence time, smoking, history of male accessory gland infections, varicocele and the year in which semen analysis was performed. When comparisons were performed among quartiles of increasing age, the fourth quartile, corresponding to the age group > 40 years, was associated with a significant decrease in total and progressive motility. An earlier decline in the TPMC and percentage of normal forms was also observed. CONCLUSION: Advancing male age exhibits an independent association with a decrease in the percentage of motile and morphologically normal spermatozoa, with greater evidence from the age of > 40 years. Further studies are warranted to elucidate the mechanisms and clinical reflections of these associations.

Association between urinary bisphenol A concentrations and semen quality: A meta-analytic study.

Although preclinical research has revealed disrupting effects on male reproductive functions of bisphenol A (BPA), as yet clinical studies have led to inconsistent results. The present meta­analysis aims to establish the existence and the extent of the association between BPA exposure and semen quality. A thorough search of PubMed, Scopus and Web of Science databases was carried out. Only studies reporting data from multivariable linear regression analyses (ß-coefficients with 95% CI), assessing the association between urinary levels of BPA and standard semen parameters were included. Nine studies provided information about an overall sample of 2,399 men. Only the negative association between urinary BPA levels and sperm motility reached statistical significance (pooled ß-coefficient = -0.82; 95% CI: -1.51 to -0.12, p = 0.02; Pfor heterogeneity = 0.1, I2 = 42.9%). Yet, such a significance was lost after data adjustment for publication bias, as well as at the sensitivity analysis, when each of the two studies that contributed most to the overall estimate was excluded. In conclusion, the overall estimates of data produced by clinical studies point to a clinically negligible, if any, association between urinary BPA concentrations and semen quality. Further studies in workers at high risk of occupational exposure are warranted to corroborate the herein revealed weak correlation with a worse sperm motility.

Pathophysiology of Mitochondrial Dysfunction in Human Spermatozoa: Focus on Energetic Metabolism, Oxidative Stress and Apoptosis.

The dogma of mitochondria as the major source of energy in supporting sperm motility should be critically reconsidered in the light of several experimental data pointing to a major role of glycolysis in mammalian spermatozoa. In this light, the reported positive correlation between the mitochondrial membrane potential (ΔΨm) and motility of ejaculated spermatozoa cannot be explained convincingly by an impaired mitochondrial ATP generation only. Evidence has been produced suggesting that, in human sperm, dysfunctional mitochondria represent the main site of generation of reactive oxygen species (ROS). Furthermore, in these organelles, a complex bidirectional relationship could exist between ROS generation and apoptosis-like events that synergize with oxidative stress in impairing sperm biological integrity and functions. Despite the activity of enzymatic and non-enzymatic antioxidant factors, human spermatozoa are particularly vulnerable to oxidative stress, which plays a major role in male factor infertility. The purpose of this article is to provide an overview of metabolic, oxidative and apoptosis-like inter-linkages of mitochondrial dysfunction and their reflections on human sperm biology.

Bisphenol A and Male Fertility: Myths and Realities.

Bisphenol A (BPA) represents the main chemical monomer of epoxy resins and polycarbonate plastics. The environmental presence of BPA is widespread, and it can easily be absorbed by the human body through dietary and transdermal routes, so that more than 90% of the population in western countries display detectable BPA levels in the urine. As BPA is qualified as an endocrine disruptor, growing concern is rising for possible harmful effects on human health. This review critically discusses the available literature dealing with the possible impact of BPA on male fertility. In rodent models, the in vivo exposure to BPA negatively interfered with the regulation of spermatogenesis throughout the hypothalamic-pituitary-gonadal axis. Furthermore, in in vitro studies, BPA promoted mitochondrial dysfunction and oxidative/apoptotic damages in spermatozoa from different species, including humans. To date, the claimed clinical adverse effects on male fertility are largely based on the results from studies assessing the relationship between urinary BPA concentration and conventional semen parameters. These studies, however, produced controversial evidence due to heterogeneity in the extent of BPA exposure, type of population, and enrollment setting. Moreover, the cause-effect relationship cannot be established due to the cross-sectional design of the studies as well as the large spontaneous between- and within-subject variability of semen parameters. The best evidence of an adverse effect of BPA on male fertility would be provided by prospective studies on clinically relevant endpoints, including natural or medically assisted pregnancies among men either with different exposure degrees (occupational/environmental) or with different clinical conditions (fertile/subfertile).

Altered ultrastructure of mitochondrial membranes is strongly associated with unexplained asthenozoospermia.

OBJECTIVE: To explore the contribution of an altered structure of sperm mitochondria to human asthenozoospermia. DESIGN: A retrospective study. SETTING: Andrology Clinic, University of L'Aquila. PATIENT(S): Fifteen ejaculates with forward motility (FM) ≥ 50%, and 57 asthenozoospermic ejaculates (FM <50%, sperm vitality >50%), including 14 ejaculates with systematic genetic defects of tail principal piece, and 43 ejaculates with unexplained asthenozoospermia. INTERVENTION(S): Fifty sections of tail middle piece (MP) were blindly analyzed by transmission electron microscopy in each ejaculate for normal mitochondrial membrane organization, after exclusion of tails with disrupted cell membranes. MAIN OUTCOME MEASURE(S): Percentage of MPs with normal mitochondrial membranes (% normal MPs). RESULT(S): Percent normal MPs showed a strong correlation with forward motility. Variation of % normal MPs explained a 45% variation of sperm motility at multivariate linear regression analysis, confirming the strong association between the two parameters in a population including ejaculates with normal motility and with unexplained asthenozoospermia. Percent normal MPs was significantly reduced in severe unexplained asthenozoospermia (FM <10%; n = 16) compared with samples with normal motility (FM ≥ 50%; n = 15); 21% (10.5%-38%) and 68% (52%-73%), respectively. CONCLUSION(S): Structural defects in mitochondrial membranes represent a main feature of severe unexplained asthenozoospermia.

Protein tyrosine phosphorylation of the human sperm head during capacitation: immunolocalization and relationship with acquisition of sperm-fertilizing ability.

The occurrence of tyrosine phosphorylation (TP) in the sperm head during capacitation has been poorly investigated, and no data exist on the relationship of its dynamics with the acquisition of sperm fertilizing ability. This study localized TP of head proteins in human spermatozoa during capacitation and explored its relationship with acquisition of the ability to display progesterone (P)-stimulated acrosome reactions (ARs) and to penetrate zona-free hamster oocytes. By immunofluorescence, TP immunoreactivity was revealed in the acrosomal region of formaldehyde-fixed/unpermeabilized samples, whereas it was abolished in fixed/permeabilized samples, in which TP immunoreactivity was high in the principal piece. No TP immunoreactivity was detectable in unfixed spermatozoa. Head TP immunoreactivity was localized externally to the acrosome, close to the cytoplasmic membrane, as assessed by transmission electron microscopy. The increase in head TP was an early event during capacitation, occurring within 1 h in capacitating conditions. At this time, the P-stimulated ARs were also increased, whereas egg penetration was as poor as in uncapacitated spermatozoa. At 5 h of capacitation, the extent of neither head TP nor the P-induced ARs were greater than that at 1 h, whereas egg penetration had significantly increased. Seminal plasma inhibited head TP, P-induced ARs and egg penetration. None of these inhibitory effects, unlike those on tail TP, were prevented by the cAMP analogue dbcAMP (N,2-O-dibutyryladenosine 3',5'-cyclic monophosphate). In conclusion, head TP is a subsurface event occurring early during capacitation and is closely related to acquisition of the ability to display P-stimulated ARs, whereas the ability to fuse with oolemma and to decondense is a later capacitation-related event.

Seminal macrophages in ejaculates from men with couple infertility.

Seminal macrophages are occasionally reported though their relevance in the evaluation of human ejaculate is unknown. Activated macrophages, engaging in sperm phagocytosis (spermiophages), might represent a marker of innate immunosystem activation. We investigated whether the presence of spermiophages in non-leukocytospermic ejaculates from men complaining for couple infertility is associated with altered sperm features. Four hundred and thirty-four ejaculates were retrospectively analysed after excluding samples with antisperm antibodies, or a leukocyte number >or=1 x 10(6)/mL. Semen quality was compared in samples with or without spermiophages detected with transmission electron microscope. Presence of spermiophages, observed in 27% of ejaculates, was associated with a decreased number of sperm total count (p < 0.0001), of sperm forward motility (p = 0.048), and to an increased fraction of degenerating sperm (p = 0.0002) compared to ejaculates without spermiophages. A low number of total ejaculated sperm and an increased number of degenerating sperm independently predicted the presence of spermiophages (odds ratio 1.72; 95% confidence intervals 1.10 to 2.28 and odds ratio 1.85; 95% confidence intervals 1.19 to 2.88 respectively). Data demonstrate that activated macrophages, a marker of the innate immunosystem activation, are frequently observed in non-leukocytospermic ejaculates of men suffering for couple infertility and this may be associated with altered sperm parameters. Ultrastructural analysis gives qualitative informations, hence sensitive quantitative tests should better define the association between semen activated macrophages and oligoasthenozoospermia and the possible relevance of this finding in the clinical evaluation of the male partner of couple infertility.

Isolated teratozoospermia: a cause of male sterility in the era of ICSI?

Single structural defects involving the totality of ejaculated sperm are among rare cases of untreatable human male infertility. This form of infertility is of genetic origin and is generally transmitted as an autosomal recessive traits. Acrosome agenesis or globozoospermia results from perturbed expression of nuclear proteins or from an altered Golgi-nuclear recognition during spermiogenesis. Failed fertilization after intracytoplasmic sperm injection (ICSI) of acrosomeless sperm is consistent with an inability of sperm to activate oocytes. Acephalic spermatozoa result from a head-neck defect due to a failure of migration of the tail anlagen and related centriole to the caudal pole of spermatids. An abnormal sperm centrosome function may explain the defective embryo cleavage after ICSI with sperm carrying a fragile head-neck junction. Primary cilia dyskinesia (PCD) and dysplasia of the fibrous sheath (DFS) are isolate defects associated with absent or greatly reduced sperm motility due to an abnormal ciliary structure and function (PCD) or to a disorganized fibrous sheath (DFS). Numerous defective genes are potentially involved in human isolated teratozoospermia but such defects have not been defined at the molecular level in most cases. IVF-ICSI is the only available method for obtaining live births with sperm carrying these defects, but the outcome is poor and the genetic risk for the subsequent generation can not be determined.

Utrastructural analysis of asthenozoospermic ejaculates in the era of assisted procreation.

OBJECTIVE: To define by transmission electron microscopy (TEM) analysis, the prevalence of sperm tail defects of genetic origin among men suffering for a reduced or absent sperm motility. DESIGN: A retrospective study. SETTING: Andrology Clinic, University of L'Aquila, Italy. PATIENT(S): The 120 ejaculates of infertile men with a forward motility (FM) < or =20% were compared to 200 ejaculates with a FM >20%. All ejaculates had a sperm vitality >50%. INTERVENTION(S): Some 25-50 tails were analyzed by TEM in each ejaculate. MAIN OUTCOME MEASURE(S): Receiver operating characteristics (ROC) analysis was applied by plotting the FM of cases with or without genetic tail defects detected by TEM. RESULT(S): The area under the ROC curve was 0.96 (95% confidence interval 0.92-0.98). The positive predictive accuracy for genetic tail defects in ejaculates with 0% FM was 46%. Three of 17 cases with genetic tail defects were classified as false negative when TEM analysis was restricted to ejaculates with 0% FM. A FM < or =7%, allowed the identification of all cases with genetic tail defects. CONCLUSION(S): The TEM analysis identifies sperm tail defects of genetic origin and should be restricted to ejaculates with severe asthenozoospermia (< or =7% motile sperm) and sperm vitality >50%.

The contractile wall of the caput epididymidis in men affected by congenital or postinflammatory obstructive azoospermia.

The transport and storage of spermatozoa in the epididymis depend on the contractile activity of its tubular wall. It is not known what differences exist in the contractile wall of the human epididymis in cases of obstructive azoospermia. The contractile wall in the tubules of the caput epididymidis was analyzed by light microscopy and transmission electron microscopy in 10 azoospermic men, 5 with a bilateral congenital absence of vas deferens (CBAVD) and 5 with a bilateral postinflammatory congestive obstruction of the epididymis. Five specimens from the same region of the caput epididymidis, obtained from fertile men who had undergone an orchidectomy because of testicular cancer, served as controls. No differences were observed between congenital and congestive obstructions. The contractile wall in caput tubules proximal to the obstructed level was strongly thickened when compared with controls (62.98 +/- 5.84 micro; 80.82 +/- 7.72 micro vs 19.59 +/- 2.23 micro, respectively, for congestive and congenital obstructions vs controls; P <.0001 vs controls), and the spindle-shaped myoid cells, which formed the contractile wall in normal cases, were replaced by large smooth muscle cells (SMCs) that showed features of coexisting contractile and secretory functions. The former included crowded cytoplasmic bundles of thin myofilaments (5-6 nm in diameter) converging to a large number of dense bodies, numerous micropinocytotic vesicles of the plasma membrane, and a continuous cell basement membrane. The presence of a developed rough endoplasmic reticulum and a Golgi complex, associated with the accumulation of thick layers of pericellular basement membrane-like material and ground substance, was indicative of a secretory phenotype of SMCs. The increased mechanical forces on the epididymal wall upstream from the obstruction might eventually activate the differentiation of myoid cells into SMCs, leading to an altered physiology of the contractile wall that could have possible clinical relevance in the case of microsurgical epididymovasostomy.

Fas expression correlates with human germ cell degeneration in meiotic and post-meiotic arrest of spermatogenesis.

Degeneration of human male germ cells was analysed by means of light (LM) and transmission electron (TEM) microscopy. The frequency of degenerating cells was correlated with that of Fas-expressing germ cells in human testes with normal spermatogenesis (n = 10), complete early maturation arrest (EMA) (n = 10) or incomplete late maturation arrest (LMA; n = 10) of spermatogenesis. LM analysis of testis sections with normal spermatogenesis indicated that degenerating germ cells were localized in the adluminal compartment of the seminiferous epithelium. TEM showed that apoptotic cells were mostly primary spermatocytes and, to a lesser extent, round or early elongating spermatids. Apoptotic germ cells appeared to be eliminated either in the seminiferous lumen or by Sertoli cell phagocytosis. An increased number of degenerating cells was observed in testes with LMA as compared with normal testes and testes with EMA of spermatogenesis (P < 0.001, Wilcoxon's rank sum test). Comparison of these results with those obtained from immunohistochemistry experiments demonstrated a tight correlation between the number of apoptotic cells and the number of Fas-expressing germ cells (P = 0.001, Spearman's rank = 0.69). These findings suggest that altered meiotic and post-meiotic germ cell maturation might be associated with an up-regulation of Fas gene expression capable of triggering apoptotic elimination of defective germ cells.