Influence of age on sperm production and testicular weights in men

Age-related changes in daily sperm production (DSP) and testicular weights were investigated in paired testes from 89 men aged 21-50 years and 43 men aged 51-80 years. For both DSP/testis and DSP/g parenchyma, remarkably large standard deviations exceeded 50% of mean values. However, DSP/g and DSP/testis for both right and left testes were approximately 30% higher in the younger than in the older group (P less than 0.01) and were negatively correlated with age (P less than 0.01) when data from both groups were pooled. Weights of whole testes and of testicular parenchyma were similar in both age groups and were not significantly correlated with age. However, testicular tunic weights were 29% higher in the older group (P less than 0.001) and were positively correlated with age (P less than 0.001). Both testicular tunic weight and the % of total testis occupied by tunic were negatively correlated with DSP/g (P less than 0.01); these correlations were weakened by removing the effect of age. Although total testicular weight and testicular parenchymal weight did not change with age, these values were about 10% lower on the left than on the right (P less than 0.001). In addition to its increase with age, testicular tunic weight was about 8% greater for right than for left testes in all men (P less than 0.001). Although the average size of the testis varied from right to left, DSP/g was similar in paired testes (P = 0.15), and the correlation between right and left DSP/g was high (rho = +0.89, P less than 0.001).(ABSTRACT TRUNCATED AT 250 WORDS)     

Cryobanking mammalian embryos: Priorities and the optimal choice of reproductive technologies

This article reviews the main achievements in embryo cryobanking in conservation and preservation of animal strains, breeds, and species. Modern advances in this technology with respect to the main groups of laboratory and farm animals are discussed. Alternative approaches to solving the problems associated with cryobanking are considered and the priorities are substantiated. Special attention is given to discussing the role of cryobanks and respective reproductive technologies in programs aimed at conservation of genetic resources of wild and endangered mammalian species.     

Father absence predicts age at sexual maturity and reproductive timing in British men

Despite the widespread assumption that paternal investment is substantial in our species, previous studies have shown mixed results in relation to the impact of fathers on both offspring survival and reproductive outcomes. Using data from a large representative sample of British men, we tested whether father absence is associated with the timing of reproduction-related events among boys, while controlling for various cues denoting early childhood adversity. We further tested whether the loss of the father at different childhood stages matters, so as to assess whether early life is the most important period or if effects can be seen during later childhood. The results show that father absence before age seven is associated with early reproduction, while father absence between ages 11 and 16 only is associated with delayed voice-breaking (a proxy for puberty), even after adjusting for other factors denoting childhood adversity. We conclude that fathers do exert an influence on male reproductive outcomes, independently of other childhood adversities and that these effects are sensitive to the timing of father absence.     

Cryobanking of lemur spermatozoa

Artificial inseminations using fresh semen were successful inLemur fulvus mayottensis. Inseminations with frozen semen are in progress.     

Role of Semen Cryobanking in American Medicine

In the United States there is little public policy regulating the activities of semen cryobanks. The medical profession has also been conspicuously silent on this aspect of medical practice. The potential benefits of semen cryobanking are enormous, yet like all other technologies its application (particularly commercially) may produce unexpected and unwanted consequences. It is suggested that a co-operative effort is needed between public officials and the medical profession to establish standards and guidelines which would maximize the benefits of this technique.     

Establishment of spermatogenesis in neonatal bovine testicular tissue following ectopic xenografting varies with donor age

Ectopic testicular xenografting can be used to investigate spermatogenesis and as an alternative means for generating transgenic spermatozoa in many species. Improving the efficiency of spermatogenesis in xenografted testicular tissue will aid in the application of using this approach. The present study was conducted to evaluate age-related differences in the establishment of spermatogenesis in grafted testicular tissue from bulls between 2 and 16 wk of life. Testicular tissue was ectopically xenografted under the skin on the backs of castrated nude mice and subsequently evaluated for growth, testosterone production, and establishment of spermatogenesis 24 wk after grafting. The greatest weight increases occurred in donor tissue from calves of the ages 2, 4, and 8 wk compared with the ages of 12 and 16 wk. Recipient mouse serum testosterone concentration was at normal physiological levels 24 wk after grafting and no significant differences were detected between recipients grafted with testicular tissue from bull calves of different ages. The development of germ cells to elongated spermatids were observed in seminiferous tubules of grafts from donor calves of the ages 4, 8, 12, and 16 wk but not observed in grafts from 2-wk donors, which contained round spermatids as the most advanced germ cell stage. Grafts from 8-wk donors contained a significantly higher (10-fold) average percentage of seminiferous tubules with elongated spermatids than all other donor ages. These data demonstrate differences in the ability of testicular tissue from donor animals of different ages to establish spermatogenesis following ectopic testicular xenografting.     

Localization of follicle-stimulating hormone (FSH) immunoreactivity and hormone receptor mRNA in testicular tissue of infertile men

Testicular biopsies from 82 oligo-or azoospermic male patients were subjected to immunostaining using anti-human FSH antibodies. Histological evaluation showed normal spermatogenesis (nspg) in 7 (FSH: 2.7±0.7), mixed atrophy (ma) in 63 (FSH:5.3±0.5), and bilateral or unilateral Sertoli Cell Only syndrome (SCO) in 12 (FSH:21.7±3.5) patients. For the relationship between FSH values and testicular histology, see Bergmann et al. (1994). FSH immunoreactivity was found exclusively in Sertoli cells and in some interstitial cells. Seminiferous epithelium showing normal or impaired spermatogenesis displayed only weak immunoreactivity compared to intense immunoreaction, i.e. large and numerous vesicles in Sertoli cells of SCO tubules in biopsies showing mixed atrophy or SCO. In addition, h-FSH receptor mRNA was demonstrated by in situ hydridization using biotinylated cDNA antisense oligonucleotides. Hybridization signals were found within the seminiferous epithelium exclusively in Sertoli cell cytoplasm associated with normal spermatogenesis and in epithelia showing different signs of impairment, including SCO. It is concluded that: (1) Sertoli cells are the only cells within the seminiferous epithelium expressing FSH receptors; (2) the accumulation of FSH immunoreactivity in Sertoli cells of SCO tubules appears to be a sign of impaired Sertoli cell function.     

The effect of donor age on progression of spermatogenesis in canine testicular tissue after xenografting into immunodeficient mice

The objective of this study was to examine the effect of donor age on progression of spermatogenesis in dog (Canis lupus familiaris) testis tissue after xenografting. In Experiment 1, canine testes were obtained by surgical castration. Based on developmental pattern of spermatogenesis at the time of grafting, donors were categorized as immature, young, and adult (<4, 4 to 6, and >6 mo old, respectively). Fragments of testis tissue were implanted subcutaneously on the back of immunodeficient mice; xenografts were retrieved and analyzed 4, 6, or 8 mo later. At 4 mo postgrafting, immature and young groups had higher graft recovery rates, graft weights, vesicular gland indices, seminiferous tubule numbers, and larger seminiferous tubular diameters compared with those of adult donor xenografts. At 8 mo postgrafting, immature donor xenografts had maintained growth and development as exhibited by greater graft weights, vesicular gland indices, seminiferous tubule numbers, and tubular diameters compared with those of adult donor xenografts. At this time point, growth and development of xenografts did not differ between immature and young donors, whereas those from young donors had greater seminiferous tubule numbers and diameters compared with those of adult donor xenografts. Elongated spermatids were the most advanced germ cell type present at 4 and 8 mo postgrafting in xenografts of immature age groups. In Experiment 2, the longer-term efficiency of spermatogenesis and the potential sperm production in xenografts from immature donor dogs were determined. Testis tissue from 2-mo-old donor dogs were grafted into recipient mice, and xenografts were retrieved after 13 mo. Complete spermatogenesis was present in 5 of 29 recovered xenografts, with isolation of fully formed sperm (up to 36.3 × 10⁶ per gram tissue). In conclusion, immature and young donors (<6 mo of age) were the most promising donors for dog testis tissue xenografting. This strategy may offer an alternative for male germ-line preservation for canids that die prematurely or must be castrated before maturation.     

Innervation of the testicular interstitial tissue in reptiles

Summary In the tortoise Testudo graeca, the lizards Lacerta dugesi and Lacerta pityusensis, and the snake Natrix natrix, the innervation of the testicular interstitial tissue was studied by light and electron microscopy, the acetylcholinesterase (ache) technique, the Falck-Hillarp method for the detection of catecholamines, and the application of 6-hydroxydopamine. The intertubular spaces of the reptilian testes studied contain adrenergic nerve fibers the amount and distribution of which varies considerably both in various species and in various stages of the reproduction cycle. Nerve fibers do not enter the seminiferous epithelium. Fluorescence microscopy of the lizard testis reveals catecholaminergic varicosities which are mainly arranged around blood vessels, but do not show obvious connexions to Leydig cells. Ache-positive fibers are equally distributed in lizard testes surrounding each seminiferous tubule. In Natrix natrix ache-positive fibers are irregularly spread among groups of tubules, without showing a definite relation to Leydig cells either. By electron microscopy bundles of unmyelinated axons and axon terminals can be more easily detected in the testes of immature animals than in adult. Terminals of nerve fibers containing small (400–500 Å in diameter) and large (800–1400 Å) dense-cored vesicles and sometimes small clear vesicles establish contacts with Leydig cells. Three types of contact are described. 1. Contacts par distance at a distance of about 2000 Å and basal lamina interposed; 2. membranous contacts having a 200 Å gap only between axolemma and Leydig cell plasmalemma; 3. invaginations of terminals into Leydig cell perikarya. The latter may exhibit surface specialisations, which strongly resemble postsynaptic membrane thickenings. Experiments using 6-hydroxydopamine underline the adrenergic character of testicular nerve fibers, which can be regarded as another example of non-cholinergic, ache-positive neurons. In the testis of the immature tortoise profiles of axons occur which probably represent purinergic, ache-positive neurons.Supported by a grant from the Deutsche Forschungsgemeinschaft (Un 34/1).I am much indebted to Mrs. R. Sprang for her skillfull technical assistance.     

Risk of testicular cancer in subfertile men: case-control study

ObjectiveTo evaluate the association between subfertility in men and the subsequent risk of testicular cancer.DesignPopulation based case-control study.SettingThe Danish population.ParticipantsCases were identified in the Danish Cancer Registry; controls were randomly selected from the Danish population with the computerised Danish Central Population Register. Men were interviewed by telephone; 514 men with cancer and 720 controls participated.ResultsA reduced risk of testicular cancer was associated with paternity (relative risk 0.63; 95% confidence interval 0.47 to 0.85). In men who before the diagnosis of testicular cancer had a lower number of children than expected on the basis of their age, the relative risk was 1.98 (1.43 to 2.75). There was no corresponding protective effect associated with a higher number of children than expected. The associations were similar for seminoma and non-seminoma and were not influenced by adjustment for potential confounding factors.ConclusionThese data are consistent with the hypothesis that male subfertility and testicular cancer share important aetiological factors.

Key messages

• The incidence of testicular cancer has increased in the past 50 years, and there is some evidence to suggest that sperm quality has decreased in the same period
• It has been hypothesised that common aetiological factors may exist for testicular cancer and for male subfertility
• The association between male subfertility and subsequent risk of testicular cancer is strong and consistent with the hypothesis of a common aetiology
• The association is similar for seminoma and non-seminoma, and it persists when several potentially confounding factors are taken into account

     

Normal reproductive development of pigs produced using sperm retrieved from immature testicular tissue cryopreserved and grafted into nude mice

Xenografting of immature testicular tissue combined with cryopreservation can preserve and use genetic information of prepubertal animals. For establishment of this new approach, it is essential to clarify whether offspring derived from sperm grown in host mice harboring cryopreserved xenografts show normal reproductive development. This study examined serum profiles of gonadal hormones during sexual maturation in pigs generated by intracytoplasmic sperm injection using sperm derived from cryopreserved xenografts (CryoXeno pigs; three males and three females). We also assessed the reproductive abilities of the male CryoXeno pigs by mating them with conventionally produced (conventional) pigs, and by examining the in vitro fertilizing ability of their sperm. For female CryoXeno pigs, reproductive ability was evaluated by artificial insemination with semen from a conventional boar. During the growth of male CryoXeno pigs, the serum concentrations of inhibin and testosterone showed similar changes (P > 0.17) to those in conventional pigs (n = 4). Histologic analyses of the testes revealed no differences (P > 0.2) in the growth and differentiation of seminiferous tubules between CryoXeno and conventional pigs. Three conventional sows delivered 13.0 ± 1.0 (mean ± standard error of the mean) live piglets after being mated with the three CryoXeno males. Sperm obtained from all CryoXeno pigs had the ability to penetrate oocytes, and these fertilized oocytes reached the blastocyst stage in vitro. During the growth of female CryoXeno pigs, the serum inhibin profile was similar (P > 0.17) to that observed in conventional pigs (n = 5). The first rise in serum progesterone concentration to more than 2 ng/mL was noted at 32.0 ± 2.3 weeks of age in the CryoXeno pigs and at 32.0 ± 3.3 weeks in the conventional pigs, suggesting that both pigs reached puberty at a similar age. After puberty, female CryoXeno pigs farrowed 8.3 ± 1.7 (mean ± standard error of the mean; n = 3) live piglets after artificial insemination with semen from a conventional boar. In conclusion, these findings demonstrate that both male and female CryoXeno pigs have normal reproductive abilities.     

Two estrogen receptors in reproductive tissue

2 estrogen binding proteins of distinct high and low affinity, previously observed in calf and rat uteri, were observed in both chicken oviductal tissue and human uterine tissue. Charcoal binding and hydroxylapatite assays were performed and data were analyzed by Scatchard plot analysis. Diethylstilbestrol was used for stimulation in assay. The 2 cytoplasmic components were specific for estrogens and had equilibrium dissociation constants of 1010 and 109M. 2 binding components of similar affinities were also detected in nuclei isolated from oviducts and uteri which had been exposed to the diethylstilbestrol. Because the 2 components have now been established in widely divergent species, the presence of 2 putative estrogen receptors should be considered commonplace and that information should be used when considering steroid hormone action on the molecular level.     

Morphometric studies on mink testicular tissue

The mink, a seasonal breeder of great economic importance, shows a high incidence of male infertility. This problem has forced investigators to find methods of assaying male mink infertility. In this study, morphometric studies have been performed on testicular tissue of a total of 31 males eliminated from breeding after testicular palpation, sperm test, and estimation of serum testosterone concentrations. Males having low sperm quality or disturbed testicular development (n=24) had significantly (p<0.01) lower numbers of spermatocytes, spermatids, and freefloating luminal spermatozoa. compared with males with good sperm quality (n=7). No differences were found in the numbers of spermatogonia, Sertoli, and Leydig cells. Other morphometric parameters such as mean diameter, mean area, mean volume, percentage of area, and surface area per volume of nuclei are also presented for each cell type in the testis. It may be concluded that the sperm test is best suited for assessing fertility in mink. Severe disturbances in testicular development can be detected by testicular palpation and serum testosterone measurements.     

Oscillations in joint synchrony of reproductive hormones in healthy men

Negative-feedback (inhibitory) and positive-feedforward (stimulatory) processes regulate physiological systems. Whether such processes are themselves rhythmic is not known. Here, we apply cross-approximate entropy (cross-ApEn), a noninvasive measurement of joint (pairwise) signal synchrony, to inferentially assess hypothesized circadian and ultradian variations in feedback coupling. The data comprised simultaneous measurements of three pituitary and one peripheral hormone (LH, FSH, prolactin, and testosterone) in 12 healthy men each sampled every 10 min for 4 days (5,760 min). Ergodicity, due to the time series stationarity of the measurements over the 4 days, allows for effective estimation of parameters based upon the 12 subjects. Cross-ApEn changes were quantified via moving-window estimates applied to 4-day time series pairs. The resultant ordered windowed cross-ApEn series (in time) were subjected to power spectrum analysis. Rhythmicity was assessed against the null hypothesis of randomness using 1,000 simulated periodograms derived by shuffling the interpulse-interval hormone-concentration segments and redoing cross-ApEn windows and spectral analysis. By forward cross-ApEn analysis, paired LH-testosterone, LH-prolactin, and LH-FSH synchrony maintained dominant rhythms with periodicities of 18-22.5, 18, and 22.5 h, respectively (each P < 0.001). By reverse (feedback) cross-ApEn analysis, testosterone-LH, testosterone-prolactin, and testosterone-FSH synchrony cycles were 30, 18, and 30-45 h, respectively (each P ≤ 0.001). Significant 8- or 24-h rhythms were also detected in most linkages, and maximal bihormonal synchrony occurred consistently at ～0400-0500. Collectively, these analyses demonstrate significant ultradian (<24 h), circadian (～24 h), and infradian (>24 h) oscillations in pituitary-testis synchrony, wherein maximal biglandular coordination is strongly constrained to the early morning hours.     

Status of local reproductive tract immunity in men with inflammatory diseases of the reproductive system

The clinico-immunological study of 80 patients with chronic prostatitis of different etiology was carried out. As controls, 20 healthy adult males were used. Mucous membranes of the reproductive tract were found to have different mechanisms of antimicrobial protection whose disturbances led to the inflammatory process. The clinico-immunological analysis carried out in the course of this study made it possible to state that, in contrast to healthy adults, pronounced changes in the characteristics of the local immunity status of the reproductive system occur in chronic prostatitis patients.     

The regenerative capacity of testicular interstitial tissue

Summary A single intraperitoneal injection of ethane dimethanesulphonate (EDS) destroys all Leydig cells in the adult rat testis but 1–2 weeks later new foetal-type Leydig cells begin to regenerate within the interstitial tissue. A further EDS treatment at 4 weeks failed to kill the new population of foetal-type Leydig cells. Between 10–20 weeks, the new Leydig cells exhibited the characteristics of adult-type Leydig cells. These cells responded to another EDS treatment by exhibiting a second phase of complete degeneration followed by regeneration of a foetal-type and subsequently an adult-type cell population. The results indicate that the testis retains the ability to replenish its supply of Leydig cells despite successive phases of total degradation of Leydig cells.     

Branched-chain amino acid aminotransferase in mouse testicular tissue

Branched-chain amino acid aminotransferase (L-leucine:2-oxoglutarate aminotransferase, EC 2.6.1.6) activity was determined in several tissues of the mouse. Testis homogenates presented a specific activity very close to that of heart extracts which were the most active. Enzyme activity was detectable in testes from 5-day-old mice and increased steadily during development to reach a maximum at the 20th day of life. The transaminase was present in the cytosol of testicular homogenates and also associated, probably in the matrix, with a special type of mitochondria present in spermatozoa and gametogenic cells. The enzyme from testis is active against the three branched-chain amino acids and catalyses the reaction in both directions. Highest activity and lowest Km were obtained with L-leucine. Activity with L-valine was the lowest. The enzyme from the mitochondrial fraction showed identical properties to that from the soluble phase. The possible participation of this aminotransferase in a shuttle system transferring reducing equivalents from cytoplasm to mitochondria is postulated.