Biomedical subjects

C H Muller

Publications and source records attributed to C H Muller.

At least 19 recordsLinked to original sources

PubMed2006

Miglustat has no apparent effect on spermatogenesis in normal men.

BACKGROUND: In mice, administration of the glycosphingolipid biosynthesis inhibitor miglustat results in reversible infertility, characterized by impaired sperm motility and markedly abnormal sperm morphology. This observation suggested that miglustat might have utility for fertility control in man. To ascertain the impact of miglustat on human spermatogenesis, we conducted a pilot study of miglustat administration in normal men. METHODS: After a 2-week baseline period, seven normal men were administered miglustat 100 mg, orally, twice daily for 6 weeks. During treatment, subjects had frequent seminal fluid analyses to assess the impact of treatment on sperm concentration, motility and morphology and the ability to undergo the acrosome reaction by in vitro assays. RESULTS: Five subjects completed all aspects of the study. In these subjects, there was no apparent effect of miglustat on sperm concentration, motility or sperm morphology after 6 weeks of therapy. In addition, no changes in acrosome structure or function were observed with treatment, despite therapeutic concentrations of miglustat in the serum and seminal plasma. All subjects experienced gastrointestinal upset, diarrhoea and mild weight loss during treatment. No other abnormalities in blood counts, serum chemistries, vision or overall health were observed. CONCLUSION: In contrast to the observations in mice, the oral administration of miglustat does not appear to affect human spermatogenesis. Further elucidation of the mechanism underlying the species specificity of miglustat may improve our understanding of the role of glycosphingolipids in spermatogenesis and result in alternative approaches to male fertility control.

1-Deoxynojirimycin↗

PubMed2001

Comparison of microscopic methods for detecting inflammation in expressed prostatic secretions.

PURPOSE: We evaluated microscopic methods of detecting inflammation in expressed prostatic secretions. MATERIALS AND METHODS: Methods of counting expressed prostatic secretion leukocytes were compared in 251 samples from 159 patients with chronic prostatitis/chronic pelvic pain syndrome, including traditional wet mounts, hemocytometer derived concentrations and expressed prostatic secretion smears stained with Gram's method or DiffQuick stain (Dade International, Inc., Miami, Florida). RESULTS: Of 159 initial patient evaluations 84 (53%) showed inflammation by hemocytometer concentration at 500 leukocytes per mm.3 or greater but only 37 (23%) were considered inflammation by the traditional wet mount method (p <0.001). Inflammation was identified in 149 of 251 specimens (59%) by hemocytometer but in only 82 (33%) by wet mount (p <0.001). When inflammation was defined as 1,000 leukocytes per mm.3 or greater the hemocytometer still identified significantly more patients (41%) and specimens (48%) with inflammation than the wet mount. The hemocytometer method had a substantially lower interassay and intra-assay coefficient of variation than the wet mount method. Polymorphonuclear neutrophils and macrophages were the most common cells observed on stained smears, which detected inflammation in 147 specimens (59%) by DiffQuick but in only 98 (39%) by Gram's method. CONCLUSIONS: Detecting inflammation in expressed prostatic secretions is method dependent. Significantly more cases of inflammation were detected by hemocytometer than by the traditional wet mount technique. Because the wet mount method also proved more variable than the hemocytometer and highly sensitive to volume, its use is not recommended. These findings support the adoption of hemocytometer and staining methods for accurate evaluation of expressed prostatic secretion inflammation in men with chronic prostatitis/chronic pelvic pain syndrome.

Adolescent↗

PubMed1999

Deletion of type IIalpha regulatory subunit delocalizes protein kinase A in mouse sperm without affecting motility or fertilization.

Cyclic AMP stimulates sperm motility in a variety of mammalian species, but the molecular details of the intracellular signaling pathway responsible for this effect are unclear. The type IIalpha isoform of protein kinase A (PKA) is induced late in spermatogenesis and is thought to localize PKA to the flagellar apparatus where it binds cAMP and stimulates motility. A targeted disruption of the type IIalpha regulatory subunit (RIIalpha) gene allowed us to examine the role of PKA localization in sperm motility and fertility. In wild type sperm, PKA is found primarily in the detergent-resistant particulate fraction and localizes to the mitochondrial-containing midpiece and the principal piece. In mutant sperm, there is a compensatory increase in RIalpha protein and a dramatic relocalization of PKA such that the majority of the holoenzyme now appears in the soluble fraction and colocalizes with the cytoplasmic droplet. Unexpectedly the RIIalpha mutant mice are fertile and have no significant changes in sperm motility. Our results demonstrate that the highly localized pattern of PKA seen in mature sperm is not essential for motility or fertilization.

Acrosome↗

PubMed1999

Assessment of interlaboratory and intralaboratory sperm morphology readings with the use of a Hamilton Thorne Research integrated visual optical system semen analyzer.

OBJECTIVE: To evaluate the level of variance produced in a multicenter study with the use of a computer-assisted sperm morphology analyzer. DESIGN: A multicenter, prospective, blinded study. SETTING: Assisted reproduction research laboratories. PATIENT(S): Semen samples produced for assisted reproductive procedures. INTERVENTION(S): Hamilton Thorne Research (Beverly, MA) integrated visual optical system semen analyzers were used at five different centers to evaluate the same set of 30 slides that were prepared and numerically coded at Tygerberg Hospital in Tygerberg, South Africa. MAIN OUTCOME MEASURE(S): The percentage of normal sperm. RESULT(S): Interlaboratory coefficients of variation (CVs) ranged between 16.31% and 23.09%. One of the participating laboratories produced an approximately 14% (-6.5-7.7) limits of agreement analysis, with a CV of 11.36%, for its duplicate readings. The use of a 10% normal sperm morphology cutoff point to determine discordance levels produced rates ranging between 10% and 23.3% for the interlaboratory and intralaboratory readings. This level of discordance equates with < or = 7 of the corresponding readings from two laboratories falling into a different normal sperm morphology group (< or = 10% or >10%). CONCLUSION(S): The magnitudes of variation produced by the readings performed in our study reached the same level as for the manual evaluation of sperm morphology. A < 10% CV can be obtained if the correct quality control measures are implemented.

Adult↗

PubMed1999

Advanced semen analysis: a simple screening test to predict intrauterine insemination success.

OBJECTIVE: To determine if a simple screening test of sperm recovery through a density gradient preparation and sperm survival after a 24-hour incubation is predictive of IUI success. DESIGN: Prospective nonrandomized descriptive study. SETTING: Tertiary assisted reproductive technology center. PATIENT(S): Four hundred fourteen couples undergoing IUI for male factor and unexplained infertility. INTERVENTION(S): An advanced semen analysis, which consisted of a basic semen analysis, sperm processing through a density gradient preparation, and a 24-hour sperm incubation, was performed on all couples before beginning IUIs. MAIN OUTCOME MEASURE(S): Cumulative and per cycle pregnancy rates (PRs) were calculated for routine semen parameters, number of sperm processed through density gradient, and percent motile sperm after a 24-hour incubation. RESULT(S): None of the basic semen analysis parameters accurately predicted IUI success. When the processed total motile sperm available for insemination was > or = 10 x 10(6) and their 24-hour survival was > or = 70%, 89% (162 of 182) of couples achieved a pregnancy with a 21.4% (162 of 757) per cycle PR compared to a 2.8% (11 of 403) per cycle PR and 4.7% total PR when survival was <70%. With use of these cutoff values for the advanced semen analysis, the test had a sensitivity of 94% and specificity of 86%. CONCLUSION(S): The number of motile sperm available for insemination and especially their 24-hour survival are highly predictive of IUI success. This advanced semen analysis is an excellent screening test to evaluate couples considering IUI.

Cell Survival↗

PubMed1999

Inhibition of human sperm-zona-free hamster oocyte binding and penetration by protein C inhibitor.

Protein C inhibitor is a heparin-dependent serine protease inhibitor present in plasma at about 0.08 mumol l-1. Protein C inhibitor inhibits activated protein C and other coagulation factors. Previously, we described the presence of high protein C inhibitor levels in human semen (3.1 mumol l-1) and showed potential roles of the inhibitor in human reproduction. Here, we show that protein C inhibitor is present in an active form in follicular fluid at about 0.1 mumol l-1 and that purified, functionally active human plasma-derived and inactive, semen-derived protein C inhibitor and a synthetic peptide derived from its sequence inhibited both binding and penetration of zona-free hamster oocytes by human sperm. The binding inhibition by protein C inhibitor was dose dependent, with 50% inhibition at 0.037 mumol l-1 inhibitor (45 +/- 17 sperm per egg versus 90 +/- 23 in control experiments). The inhibitor also blocked in a dose-dependent manner the penetration of zona-free hamster eggs by human sperm (20 +/- 7% fertilized eggs at 0.1 mumol l-1 protein C inhibitor versus 55 +/- 10% in control experiments). Polyclonal antiprotein C inhibitor or antipeptide antibodies partially abolished the effect of protein C inhibitor and peptide on the inhibition of the binding and penetration of zona-free hamster oocytes by human sperm. The effect of the protein C inhibitor was not dependent on its antiprotease activity since purified semen-derived protein C inhibitor which did not have antiprotease activity gave comparable results. We conclude that protein C inhibitor may be involved in human reproduction at several steps, including the fertilization process.

Amino Acid Sequence↗

PubMed1998

Contrasting associations of blood and semen lead concentrations with semen quality among lead smelter workers.

While blood lead concentration has been inversely associated with indicators of reproductive health in occupationally exposed male workers, the utility of lead concentration in semen as an indicator of lead exposure to the male reproductive system has not been fully explored. Blood and semen lead concentrations from 81 lead smelter workers were examined in relation to semen quality and endocrine function parameters. Mean blood and semen lead concentrations were 22.8 micrograms/dl (range 5-58) and 1.9 micrograms/dl (range 0.1-17.6), respectively. Total sperm count and concentration decreased with increasing blood lead concentration; p for trend was 0.003 and 0.009, respectively. Semen lead concentration was inversely related to total sperm count (p = 0.05), ejaculate volume (p = 0.001), and serum testosterone (p = 0.004), but not to sperm concentration. The association between semen lead concentration and total sperm count was eliminated when volume was included in the model. Blood lead concentration was more consistently associated with indicators of sperm production than was semen lead. In contrast, semen lead concentration was negatively associated with circulating testosterone concentrations. Our findings indicate that measurement of semen lead may not be a valuable adjunct to conventional blood lead monitoring for investigations of male reproductive system toxicity.

Adult↗

PubMed1998

Bladder petechiae after cystoscopy and hydrodistension in men diagnosed with prostate pain.

PURPOSE: We determined if men with prostate pain syndromes have petechiae in the bladder after hydrodistension. MATERIALS AND METHODS: A total of 60 men with the diagnosis of prostate pain and without bacteriuria underwent cystoscopy and hydrodistension under a general or regional anesthetic. RESULTS: Of the 60 men 35 (58%) had moderate to severe petechiae similar in appearance to women with interstitial cystitis after hydrodistension. Men with moderate to severe bladder petechiae had fewer leukocytes in expressed prostatic secretions, smaller bladder capacities and less often testicular pain than men with more normal appearing bladders after hydrodistension. Symptomatic improvement 2 to 6 weeks after hydrodistension was more common in men with moderate to severe petechiae than in those with fewer petechiae. Absence of rectal pain predicted symptomatic improvement after hydrodistension. CONCLUSIONS: We suggest that bladder petechiae, and possibly interstitial cystitis or a related condition, may be more frequently associated with prostate pain syndromes in men than previously appreciated.

Adult↗

PubMed1998

Effects of clinical stage and immunological status on semen analysis results in human immunodeficiency virus type 1-seropositive men.

Complete semen analyses including computer-assisted sperm motility and morphology assessments were performed to determine if semen and sperm differed between HIV-seropositive men and fertile controls, or differed with symptoms, or CD4+ peripheral cell count categories. Previous studies included small numbers of men and presented conflicting conclusions. Two hundred and fifty non-vasectomized HIV-seropositive men and 38 fertile controls each provided one semen sample. Non-parameteric statistics were used to analyse both continuous and nominal data. Fertile men had significantly greater semen volume, sperm concentration, percent motility, percent rapid and linear motility and total strictly normal spermatozoa than HIV seropositive men. Neither total number nor subtypes of leukocytes in semen differed between the two groups. Among the HIV seropositive men, significant differences in semen analyses were found between CD4+ cell count, clinical, and AIDS categories. Lower CD4+ cell counts (< 200 mm-3) were associated with significantly lower percent motility, percent normal sperm morphology by strict criteria, significantly more spermatids in semen, and higher percentages of teratozoospermia, oligoasthenoteratozoospermia and leukocytospermia. Healthier men, based on clinical categories, had significantly more normal shaped spermatozoa and fewer had azoospermia, oligoasthenoteratozoospermia or leukocytospermia. Many HIV-seropositive men have normal semen analyses, but as the disease progresses more defects are found, particularly in strict criteria sperm morphology.

Acquired Immunodeficiency Syndrome↗

PubMed1998

Vasectomy reversal associated with increased reactive oxygen species production by seminal fluid leukocytes and sperm.

PURPOSE: Reactive oxygen species, which are primarily produced by leukocytes, are generally detrimental to sperm. High reactive oxygen species levels are found in men with abnormal sperm function. Since men often have poor sperm characteristics and infertility after vasectomy reversal, we compared reactive oxygen species in seminal cells of men after vasovasostomy to those of fertile men to determine if reactive oxygen species were elevated in the former group. MATERIALS AND METHODS: We studied semen samples of men with proved fertility (39) and those with previously proved fertility who had undergone vasectomy reversal (45). The presence of leukocytes was determined by Bryan-Leishman staining. Reactive oxygen species endogenous activity was monitored by luminol dependent chemiluminescence in washed cells, including all cells in the semen, and Percoll density gradient purified sperm. RESULTS: After vasovasostomy men had significantly lower sperm concentration, motility and computerized motility measurements than fertile men. Mean reactive oxygen species in washed seminal cells after vasovasostomy was 684 relative light units per second compared to 49 for fertile controls (p < 0.0001). Density gradient purified sperm had 53 and 0.64 relative light units per second, respectively (p < 0.0001). When men with leukocytospermia were excluded from analysis, differences between the groups remained, although 9 times more reactive oxygen species were detected in men after vasectomy reversal with than those without leukocytes in semen. CONCLUSIONS: Higher levels of reactive oxygen species are found in washed seminal cells and purified sperm after vasectomy reversal than in those of fertile men. Although leukocytes are probably a significant source of reactive oxygen species in these groups, they may not account for all of the increased reactive oxygen species after vasovasostomy. Low motility after vasectomy reversal may be related to the detrimental effects of reactive oxygen species produced by leukocytes or sperm, even in men without clinical leukocytospermia.

Adult↗

PubMed1997

Bacteria in the prostate tissue of men with idiopathic prostatic inflammation.

PURPOSE: Although antibiotics represent the first line of treatment for prostatitis syndromes, physicians can document infection in remarkably few cases. We examined the relationship of genitourinary infection to inflammatory prostatitis in 85 subjects without bacteriuria. MATERIALS AND METHODS: Evaluation consisted of cultures of urethra, urine and transperineal prostate biopsies, specifically for commensal and fastidious organisms, and leukocyte counts of expressed prostatic secretions. RESULTS: Men with inflamed expressed prostatic secretions (25) were more likely to have any bacterial isolation (p = 0.01), positive cultures for anaerobic bacteria (p = 0.03), higher total bacterial counts (p = 0.02) and more bacteria, species isolated (p = 0.02) in prostate biopsy cultures than men without expressed prostatic secretion inflammation (60). CONCLUSIONS: Bacterial colonization/invasion of the prostate may be associated with inflammatory prostatitis in some cases.

Adult↗

PubMed1997

Randomized clinical trial of an absorbable stent for vasectomy reversal.

PURPOSE: More successful methods of vasectomy reversal would benefit those undergoing this treatment and might also increase the popularity of vasectomy. We conducted a randomized, prospective clinical trial of vasectomy reversal methods, comparing a new absorbable stent with 2-layer reattachment. MATERIALS AND METHODS: We studied 116 men seeking vasectomy reversal between November 1990 and March 1994. Data were analyzed primarily by intention to treat. RESULTS: Patients in the stent (64 cases) and no stent (52) randomized groups were similar in age distribution, age of spouses, years since vasectomy, proportion who had undergone prior vasectomy reversal and proportion who had previously achieved pregnancy. Operation time was more than 19 minutes shorter in the stent randomized group (p = 0.006). Fewer patients in the stent than the no stent group had patent vasovasostomies (81.0 versus 89.6%, respectively, p = 0.2) postoperatively. Fewer stent randomized patients had motile sperm (76.2 versus 81.3%, respectively, p = 0.5) and normal total motile sperm counts (49.2 versus 52.1%, respectively, p = 0.8) than did those without a stent. Conception occurred in 22 and 51% of all couples in the stent and no stent groups. The relative risk of conception among those in the stent group was 0.42 (95% confidence interval 0.24 to 0.71, p = 0.002). A Mantel-Cox log-rank test comparing pregnancies in each group according to the number of postoperative months revealed that the no stent group achieved more earlier pregnancies (p = 0.003). CONCLUSIONS: The 2-layer microscopic vasovasostomy results in greater pregnancy rates than vasovasostomy using the absorbable stent.

Absorption↗

PubMed1996

Semen quality of men employed at a lead smelter.

OBJECTIVE: To evaluate the effects of recent and long term occupational lead exposure on indicators of male reproductive health. METHODS: In a cross sectional study of male employees of a lead smelter (n = 2469), blood samples were obtained from 152 workers including 119 who also provided semen samples. Semen analysis and serum concentrations of testosterone, follicle stimulating hormone, and luteinising hormone were used as indicators of reproductive health. Semen and hormone variables were examined in relation to measures of current and long term body lead burden estimated from current blood lead concentrations and historical blood lead monitoring data. RESULTS: For current blood lead concentration groups of < 15, 15-24, 25-39, > 40 micrograms/dl, the geometric mean sperm concentrations were, respectively, 79.1, 56.5, 62.7, and 44.4 million cells/ml and geometric mean total sperm counts were 186, 153, 137, and 89 million cells (P for trend 0.04). Compared with workers with blood lead concentrations less than 15 micrograms/dl, workers with current blood lead concentrations of 40 micrograms/dl or more had an increased risk of below normal sperm concentration (odds ratio (OR) 8.2, 95% confidence interval (95% CI) 1.2-57.9) and total sperm count (OR 2.6, 95% CI 0.4-15.7), based on World Health Organisation standards. Independent of current lead exposure, sperm concentration, total sperm count, and total motile sperm count were inversely related to measures of long term lead exposure. No association was found between lead exposure and measures of sperm motility, sperm morphology, or serum concentrations of reproductive hormones. CONCLUSIONS: Blood lead concentrations below the currently accepted worker protection criteria seem to adversely affect spermatogenesis.

Adult↗

PubMed1995

Stimulation of human sperm capacitation by purified lipid transfer protein.

Lipid Transfer Protein I is recognized as a key component involved in high density lipoprotein metabolism. We have been studying lipid transfer in relation to sperm capacitation, a complex series of cell surface events required for the acrosome reaction and fertilization. We have previously shown that Lipid Transfer Protein I is present and active in the female reproductive tract. In the present study, we show that purified Lipid Transfer Protein I directly stimulates human sperm capacitation, but not the acrosome reaction, in the absence of other biological effectors. These results provide strong evidence for a novel role for Lipid Transfer Protein I and reveal, for the first time, a potent activator of capacitation, prior to the acrosome reaction.

Animals↗

PubMed1995

Identification and treatment of leukocytospermia in couples with unexplained infertility.

OBJECTIVE: To evaluate whether identifying men with leukocytospermia in couples with unexplained infertility and treating them with antibiotics improves pregnancy rates. STUDY DESIGN: A prospective, cohort study of men with and without leukocytospermia was identified on a smear of semen using Bryan-Leishman stain. Cumulative six-month pregnancy rates were determined for members of the leukocytospermic group who responded to treatment with resolution of their leukocytospermia on a semen smear, those who failed to respond to treatment, those not treated and those without leukocytospermia. RESULTS: Thirty-six of 53 men with leukocytospermia responded to antibiotic treatment, and 19 women in these 36 couples (53%) became pregnant within the six-month follow-up period. Only 7 of 17 (6%) of those who failed to respond to treatment had their partner become pregnant (P < .001). Partners of men with leukocytospermia and no treatment had a 6% pregnancy rate, and the women in 13% (5/42) of couples without leukocytospermia became pregnant (P < .001). CONCLUSION: Leukocytospermia exists in a significant number of males with unexplained infertility and normal semen analyses. Identifying and successfully treating such men results in a significant improvement in pregnancy rates. These men may be a subgroup with male infertility that can be identified and treated.

Adult↗

PubMed1994

Sperm chemotaxis: egg peptides control cytosolic calcium to regulate flagellar responses.

Fragmentary evidence indicates that intracellular [Ca2+] (Cai) mediates sperm chemotaxis. However, neither correlations of swimming responses to chemoattractant-induced alterations of Cai nor explanations of how chemoattractant gradients control Cai exist. Here Cai increases produced by the egg peptide speract-not previously known to cause flagellar responses--were prolonged by treatment with 3-isobutyl-1-methylxanthine (IBMX). Flagellar waveform asymmetry then increased 40% and swimming paths became tightly circular. Moreover, both responses required external Ca2+ (as does sperm chemotaxis to eggs and egg products). Cai increases by the established chemotactic peptide resact also required external Ca2+ and were enhanced by IBMX. Therefore, diverse egg peptides may use fundamentally similar mechanisms to control Cai and thereby swimming behavior in chemotaxis. Repetitive increasing additions of speract produced adaptive membrane potential and Cai responses indicating that sperm can detect increasing gradients of egg peptide over a broad concentration range. We offer a model in which shallow or decreasing gradients elevate Cai and redirect swimming paths but sufficiently steep gradients keep Cai low and swimming linear until the egg is reached. A negative-feedback loop, initiated by cGMP-mediated activation of sperm K+ channels and terminated by subsequent inactivation of guanylyl cyclase, may coordinate gradient detection with control of Cai. Continued stimulation of more receptors by steeply increasing gradients of egg peptide thus maintains membrane hyperpolarization and suppresses Ca2+ entry and Cai elevation. The molecular basis for chemotaxis therefore is explained as translation of the spatial gradient of peptide concentration into changes in K+ channel activity in the time domain.

3',5'-Cyclic-AMP Phosphodiesterases↗

PubMed1994

Efficacy of treatment and recurrence rate of leukocytospermia in infertile men with prostatitis.

OBJECTIVE: To identify men with leukocytospermia and prostatitis in an infertility practice and evaluate the effect of various treatments and recurrence rates after treatment. DESIGN: A prospective randomized trial of men with leukocytospermia. SETTING: Academic tertiary infertility clinic. PATIENTS: One hundred two men with leukocytosperimia identified on smear of semen using Bryan-Leishman stain and in expressed prostatic secretion. INTERVENTIONS: Treatment groups were no treatment group; antibiotic treatment alone group; frequent ejaculation alone group; and antibiotic treatment with frequent ejaculation group. MAIN OUTCOME MEASURE: Resolution of leukocytospermia on semen smear. RESULTS: Significant resolution of leukocytospermia occurred in all treatment groups at 1 month compared with no treatment. The resolution was sustained at 2 and 3 months only in those who took antibiotics and frequently ejaculated. CONCLUSIONS: Antibiotic treatment, frequent ejaculation, and antibiotic treatment with frequent ejaculation effectively treat leukocytospermia immediately after the treatment phase. However, only antibiotic treatment coupled with frequent ejaculation is effective 3 months after treatment.

Adult↗

PubMed1993

A novel view of albumin-supported sperm capacitation: role of lipid transfer protein-I.

OBJECTIVE: To determine if one mechanism of albumin-mediated support of human sperm capacitation is lipid (cholesterol) transfer activity and contamination of albumin with Lipid Transfer Protein-I (LTP-I). DESIGN AND MAIN OUTCOME MEASURES: Measure lipid transfer activity in various bovine and human albumin preparations, relate this activity to albumin-supported capacitation (measured by zona-free hamster oocyte sperm penetration assay) and acrosome reactions; and attempt to detect LTP-I in active albumins. Remove LTP-I from albumin which supports capacitation and reassess this support. Reconstitute capacitation support by addition of purified LTP-I. SETTING AND SUBJECTS: Healthy sperm donors with normal semen analyses were recruited by the Reproductive Biology-Andrology Laboratory in a university medical center. RESULTS: Albumin preparations that effectively support capacitation have high levels of lipid transfer activity and of LTP-I, a protein responsible for lipid transfer activity. Preparations with lower levels of capacitation support have less lipid transfer activity. Removal of LTP-I from supportive albumin significantly reduces the capacitation support, and this is restored by purified LTP-I. Progesterone concentrations in these preparations are negligible. CONCLUSIONS: The variable abilities of albumin preparations to support in vitro sperm capacitation are largely dependent on the presence of contaminating LTP-I. The cholesterol transfer activity of this protein, which is present in human serum and follicular fluid, may be one mechanism in the process of capacitation.

Acrosome↗