Subtotal obstruction of the male reproductive tract.

Bilateral obstruction of the male reproductive tract is suspected in men with azoospermia, normal testicular volume and normal FSH. A testicular biopsy is required to differentiate between an obstruction and a testicular insufficiency. Unilateral or subtotal bilateral obstructions and epididymal dysfunction may cause severe oligozoospermia in men with a normal spermatogenesis. However, information on spermatogenesis in oligozoospermic men is lacking, since testicular biopsy is not routinely performed. Men with a sperm concentration of <1 x 10(6) spermatozoa/ml were investigated for possible partial obstruction by performing a testicular biopsy under local anaesthesia. Spermatogenesis was determined by the Johnsen scoring method. A testicular biopsy was performed in 78 men with severe oligozoospermia. The medical history showed male accessory gland infection in 12.8%, previous hernia repair in 14.1% and a history of cryptorchidism in 12.8%. A normal or slightly disturbed spermatogenesis (Johnsen score >8) was present in 39/78 (50%) of the men. Hernia repair occurred more often in men with normal spermatogenesis. A varicocele was predominantly seen in men with a disturbed spermatogenesis. FSH was significantly lower ( P<0.0001) in men with normal spermatogenesis. Subtotal obstruction of the male reproductive tract is a frequent cause of severe oligozoospermia in men with a normal testicular volume and a normal FSH. In other cases, an epididymal dysfunction might explain the oligozoospermia in men with a normal testicular biopsy score.

Increased serum inhibin B levels after varicocele treatment.

OBJECTIVE: Inhibin B is secreted by Sertoli cells in response to FSH and is the major feedback regulator of FSH secretion in man. The serum inhibin B level has emerged as a good marker of spermatogenesis and Sertoli cell function. Varicocele has been associated with infertility and disturbed spermatogenesis. We have studied the effect of varicocele treatment on serum inhibin B levels, with the aim of investigating the effect on spermatogenesis and the involvement of the Sertoli cell in varicocele pathophysiology. DESIGN AND PATIENTS: In a pre-post test design, the effect of varicocele surgery on inhibin B levels was studied in 30 infertile men. MEASUREMENTS: Endocrinology (inhibin B, FSH, LH, SHBG and testosterone) and semen analysis (sperm concentration, motility and morphology). RESULTS: In men receiving varicocele treatment, a significant increase in serum inhibin B levels was observed from 133.9 +/- 13.4 pretreatment to 167.8 +/- 16.1 ng/l after treatment (mean +/- SEM, P < 0.0001). No significant changes were observed in serum levels of FSH, LH and testosterone. The serum SHBG level decreased from 32.9 +/- 3.5 to 28.6 +/- 3.4 nmol/l (mean +/- SEM, P = 0.04) and the free androgen index was significantly increased from 66 +/- 5.9 pretreatment to 85 +/- 6.8 after treatment (P = 0.02, mean +/- SEM). Semen analysis showed a significant improvement in sperm concentration, from 6.5 +/- 1.9 pretreatment to 19.3 +/- 4.9 x 106/ml after treatment (P = 0.003, mean +/- SEM), and in sperm motility from the baseline level of 17 +/- 3 to 32 +/- 4% after treatment (P = 0.001, mean +/- SEM). CONCLUSIONS: Varicocele treatment can increase serum inhibin B levels, indicating improvement of spermatogenesis and Sertoli cell function. This finding suggests that the pathophysiology of varicocele involves impairment of Sertoli cell function or a different distribution of germ cell stages.

The advantages of standardized evaluation of male infertility.

Healthcare can be improved by standardization and by evaluation of diagnostic methods and treatments. In the field of andrology, in which large patient numbers are required for the evaluation of diagnostic procedures and treatments, structured data collection and multicentre studies are especially warranted. Concomitant with routine clinical practice, a large amount of clinical data are collected that may be used to evaluate andrological care. Structuring and electronic storage of data holds promise in terms of clarity and accessibility of the data and its use for validation studies. The aim of the present work was to study the merits of routine collection of a common dataset in a computer-based patient record (CPR) for standardization, quality of data and clinical research. It was studied whether the data were of sufficient quality and accessibility for much needed studies on aetiology, interventions and diagnostics in andrology. Data collection in a structured CPR promoted complete and comprehensive data. We describe the advantages, pitfalls and solutions with this approach. Data on the uniform examination of 1549 infertile men became readily accessible. Population characteristics, basal associations and original studies were enabled and provided insight into the efficiency of clinical practice. In 66% of men, a cause for their infertility was identified, which provides a better rationale for treatment than semen parameters alone. For more than 30% of the patients, a rational andrological treatment was available, which could be deployed before assisted reproductive technologies were resorted to. However, most treatments have not been properly validated. The thorough diagnostic evaluation identifies subgroups that require an evidence base for treatment and further study on aetiology and diagnosis. Structured collection of uniform patient data through a CPR was feasible and facilitated the evaluation of diagnostic and therapeutic modalities. The reported advantages, pitfalls and solutions with this approach may help other centres to decide on how to implement a CPR. Conscientious collection of a standard data set in infertility centres facilitates pooling of data and evidence-based multicentre research.

Is routine scrotal ultrasound advantageous in infertile men?

PURPOSE: We determine the value of routine scrotal ultrasonography in the evaluation of male infertility. MATERIALS AND METHODS: Scrotal color Doppler ultrasonography reports of 1,372 infertile men were reviewed to assess the prevalence of scrotal abnormalities and compared to clinical findings. RESULTS: The prevalence of scrotal abnormalities was 38%. Testicular tumor was found in 0.5%, varicocele in 29.7%, testicular cyst in 0.7%, testicular microlithiasis in 0.9%, epididymal cyst in 7.6% and hydrocele in 3.2% of the cases. Overall, 67% of sonography findings were not evident on palpation, and only 1 of 7 testicular tumors was suspected. Of the varicoceles 60% were not found on physical examination. The rate of testicular tumors (1/200) was higher than that reported for the general European population (1/20,000). CONCLUSIONS: Routine scrotal ultrasound provides valuable information in the diagnostic evaluation of infertile men and substantially more pathological conditions are detected compared to clinical palpation. The high prevalence of testicular malignancies underlines the clinical relevance of routine scrotal ultrasonography in infertile men.

Improvement of sperm count and motility after ligation of varicoceles detected with colour Doppler ultrasonography.

The debate regarding the efficacy of varicocele ligation for improvement of semen parameters and pregnancy rates is ongoing. In addition, no consensus exists as to the benefit of treatment of subclinical varicoceles. The aim of this study was to investigate, retrospectively, the effect of high ligation of both subclinical and clinical varicoceles on sperm count and motility. The value of several factors from history-taking and physical examination for the prediction of successful varicocelectomy was analysed. A total of 139 patients, operated on for a unilateral varicocele on the left side, were studied. Varicoceles were subclinical in 73 patients, based on colour Doppler ultrasonography, and 66 varicoceles were clinical, based on palpation in addition to ultrasonography. Comparison of semen parameters before and after surgery revealed a significant improvement. The median sperm count increased from 10.0 to 14.7, and from 18.2 to 28.6 million/ejaculate, in patients with subclinical and clinical varicoceles, respectively (p < 0.001). The percentage improvement in median sperm count in subclinical varicoceles was not statistically different from the improvement in clinical varicoceles. Mean progressive motility improved significantly after ligation (p < 0.001). The improvement in motility in subclinical varicoceles, from 16 to 23%, was significantly larger than the 24 to 27% improvement in clinical varicoceles. The increase in sperm count was related positively to testicular volume before surgery (p < 0.05). The increase in sperm motility was significantly lower in patients with a history of cryptorchidism (n = 22, p < 0.05). The present data show that ligation of varicoceles detected using Doppler ultrasonography, whether palpable or not, results in an increase in sperm concentration and motility.

Serum inhibin B as a marker of spermatogenesis.

Inhibin B is produced by Sertoli cells, provides negative feedback on FSH secretion, and may prove to be an important marker for the functioning of seminiferous tubules. The purpose of the present study was to examine the relationship between the spermatogenic function of the testis of subfertile men and the plasma concentrations of inhibin B and FSH. These parameters were estimated in a group of 218 subfertile men. Serum inhibin B levels were closely correlated with the serum FSH levels (r = -0.78, P < 0.001), confirming the role of inhibin B as feedback signal for FSH production. The spermatogenic function of the testis was evaluated by determining testicular volume and total sperm count. Inhibin B levels were significantly correlated with the total sperm count and testicular volume (r = 0.54 and r = 0.63, respectively; P < 0.001). Testicular biopsies were obtained in 22 of these men. Inhibin B was significantly correlated with the biopsy score (r = 0.76, P < 0.001). Receiver operating characteristic analysis revealed a diagnostic accuracy of 95% for differentiating competent from impaired spermatogenesis for inhibin B, whereas for FSH, a value of 80% was found. We conclude that inhibin B is the best available endocrine marker of spermatogenesis in subfertile men.

Immunoexpression of testis-specific histone 2B in human spermatozoa and testis tissue.

During mammalian spermatogenesis, the chromatin of the spermatogenic cells is profoundly reorganized. Somatic histones are partly replaced by testis-specific histones. These histones are then replaced by transition proteins and finally by protamines. This series of nucleoprotein rearrangements results in a highly condensed sperm cell nucleus. In contrast to spermatozoa from other species, human spermatozoa still contain a significant amount of histones, including testis-specific histone 2B (TH2B). In the present study it is shown that an antibody targeting tyrosine hydroxylase, which has been found previously to cross-react with rat TH2B, also specifically immunoreacts with human TH2B on Western blots, in immunohistochemistry of human testis tissue, and in immunocytochemistry of decondensed human spermatozoa. In human testis tissue, TH2B immunostaining first apparent in spermatogonia, shows marked variation, especially at the pachytene spermatocyte stage, and then reaches an intense signal in round spermatids. Shortly before spermatid elongation, a portion of the spermatid nucleus, corresponding to the acrosomal region, loses its immunoreactivity. During condensation of the spermatid nucleus, the immunodetectability of TH2B disappears gradually, from the anterior region of the nucleus onwards. At the final stages of spermiogenesis, the immunostaining is completely absent. Immunocytochemical staining of spermatozoa revealed no TH2B immunosignal, but immunostaining was observed when spermatozoa obtained from semen were decondensed to make nuclear proteins accessible to the antibody. There was, however, a striking intercellular variability in the intensity of staining of spermatozoa within an ejaculate. In a population of 35 men attending our Andrology Clinic, we observed interindividual differences in total sperm TH2B content, which showed a significant, although not very pronounced, negative correlation with normal morphology (P = 0.05).

Testis-specific expression of a functional retroposon encoding glucose-6-phosphate dehydrogenase in the mouse.

The X-chromosomal gene glucose-6-phosphate dehydrogenase (G6pd) is known to be expressed in most cell types of mammalian species. In the mouse, we have detected a novel gene, designated G6pd-2, encoding a G6PD isoenzyme. G6pd-2 does not contain introns and appears to represent a retroposed gene. This gene is uniquely transcribed in postmeiotic spermatogenic cells in which the X-encoded G6pd gene is not transcribed. Expression of the G6pd-2 sequence in a bacterial system showed that the encoded product is an active enzyme. Zymogramic analysis demonstrated that recombinant G6PD-2, but not recombinant G6PD-1 (the X-chromosome-encoded G6PD), formed tetramers under reducing conditions. Under the same conditions, G6PD tetramers were also found in extracts of spermatids and spermatozoa, indicating the presence of G6pd-2-encoded isoenzyme in these cell types. G6pd-2 is one of the very few known expressed retroposons encoding a functional protein, and the presence of this gene is probably related to X chromosome inactivation during spermatogenesis.

Comparison of the response of rat testis and accessory sex organs to treatment with testosterone and the synthetic androgen methyltrienolone (R1881).

We have studied the ability of the synthetic androgen methyltrienolone (R1881) to maintain testis and accessory organ weights, as compared to the effect of testosterone propionate (TP). In contrast to TP, R1881 is not metabolized and does not significantly bind to androgen-binding protein (ABP). Thirty-six rats were treated with ethane dimethane sulphonate (EDS) and GnRH antagonist (Org30267) to abolish all testicular androgen production, and recombinant human FSH (rec-hFSH, Org32489) was administered to ensure adequate FSH levels. Of these rats, five groups of four rats were treated daily with 0-, 50-, 100-, 200-, and 400-microgram TP, s.c., and four groups of four rats were treated daily with 150-, 300-, 600-, and 1200-microgram R1881, s.c. One control group of four rats received vehicle injections only. EDS treatment, followed by GnRH antagonist and rec-hFSH treatment for 17 days, significantly reduced testis, prostate, and seminal vesicle weights (P < 0.001, P < 0.01, P < 0.001, respectively). Simultaneous treatment with androgens prevented this organ weight decrease, in a dose-dependent manner. In all TP-treated animals, relative weights (% of control) of the acces, sory sex organs were significantly higher than the relative testis weights (P < 0.001). However, there was no difference in relative weights between testis and accessory sex organs in the R1881-treated animals. In another series of experiments, we investigated the effect of treatment with Finasteride, a 5 alpha-reductase inhibitor, on testis and accessory sex organ weights in rats treated with EDS and TP. Treatment with EDS, TP (300 micrograms/day) and Finasteride (40 mg/kg/day) did not alter testis weight as compared to the effect of treatment with EDS and TP alone. Prostate and seminal vesicle weights were, however, markedly reduced (significantly different from rats treated with EDS and TP alone; P < 0.01 and P < 0.05, respectively). Immunohistochemical analysis of androgen-receptor (AR) expression in the testis revealed that testicular AR immunoexpression is androgen dependent and that FSH alone is not able to maintain AR immunoexpression. Furthermore, the stage-dependent pattern of AR immunoexpression in Sertoli-cell nuclei, during the spermatogenic cycle, is identical in all TP- and R1881-treated rats. It is concluded that testes, prostate, and seminal vesicles are equally stimulated when the androgen receptor in these tissues is exposed to the same intracellular concentration of free androgen and that the low 5 alpha-reductase activity in the testis plays a critical role in the differential response of the testis and the accessory sex organs to T. Furthermore, stage-dependent AR immunoexpression in Sertoli cells does occur in the absence of testicular androgen production and is not due to androgen metabolism or local differences in androgen concentration.

Inactivation of the HR6B ubiquitin-conjugating DNA repair enzyme in mice causes male sterility associated with chromatin modification.

The ubiquitin-conjugating yeast enzyme RAD6 and its human homologs hHR6A and hHR6B are implicated in postreplication repair and damage-induced mutagenesis. The yeast protein is also required for sporulation and may modulate chromatin structure via histone ubiquitination. We report the phenotype of the first animal mutant in the ubiquitin pathway: inactivation of the hHR6B-homologous gene in mice causes male infertility. Derailment of spermatogenesis becomes overt during the postmeiotic condensation of chromatin in spermatids. These findings provide a parallel between yeast sporulation and mammalian spermatogenesis and strongly implicate hHR6-dependent ubiquitination in chromatin remodeling. Since heterozygous male mice and even knockout female mice are completely normal and fertile and thus able to transmit the defect, similar hHR6B mutations may cause male infertility in man.

Sexual arousal and the quality of semen produced by masturbation.

The influence of sexual arousal on the quality of semen produced by masturbation was investigated. One group of 29 patients referred to our andrology outpatient clinic (group A) and one group of 14 healthy potential sperm donors filled out a questionnaire after having produced two semen samples, at least 1 month apart, by masturbation. Changes in questionnaire scores between first and second visit were compared with changes in semen characteristics between those two occasions to identify statistically significant correlations. A second group of 23 subfertility patients (group B) were asked to produce a semen sample by masturbation in a designated room at the hospital without additional sexual stimulation, and a second sample while viewing a sexually explicit video. Differences in questionnaire scores and semen characteristics obtained with visual erotic stimulation (VES) and without VES were analysed. In group A, the change in sexual arousal and change in intensity of orgasm correlated with change in semen volume (r = 0.38, P < 0.05; r = 0.48, P < 0.01 respectively). In healthy donors and group B, however, no such correlation was found. With VES in group B, significantly higher scores were given for 'feeling at ease/relaxed' (P < 0.01), 'sexual arousal' (P < 0.001), 'quality of erection' (P = 0.01), 'intensity of orgasm' (P < 0.05), 'satisfaction after orgasm' (P < 0.05), and 'ease with which orgasm was achieved' (P < 0.001) with VES compared to without VES. There was no statistically significant improvement in semen quality with VES compared to without VES. It is concluded that sexual arousal has no significant influence on the quality of an ejaculate produced by masturbation. On the other hand, providing a patient with a sexually stimulating video is obviously a facilitative factor when the patient 'has to' produce a semen sample for analysis. The use of visual erotic stimulation is recommended when patients and donors have to produce a semen sample in the university surroundings of a fertility clinic.

Androgen receptor immunoexpression in the testes of subfertile men.

The localization and intensity of androgen receptor immunostaining was studied in the testes of 37 subfertile men with oligozoospermia and normal serum gonadotropin levels using a polyclonal antibody raised against a synthetic peptide corresponding to the first 20 N-terminal amino acid residues of the androgen receptor (AR). Furthermore, we investigated whether or not the immunoexpression of the AR in human Sertoli cells, in histologically normal testis tissue, is dependent on the stage of the spermatogenic cycle, as has been found in the rat. In the human testis, AR immunoexpression was observed in Sertoli cells, peritubular myoid cells, Leydig cells, and periarteriolar cells, but not in germinal cells. We found no evidence for a stage-dependent immunoexpression of AR in Sertoli cells. The intensity of AR immunoexpression varied substantially between biopsy specimens of different patients. There was, however, no correlation of the intensity of AR immunoexpression in either Sertoli cells or peritubular myoid cells with spermatogenic adequacy as measured by the method of Johnsen. When, in this study, the intensity of peritubular myoid cell staining was used as a standard to evaluate the intensity of Sertoli cell staining, no correlation was detected as well. Furthermore, serum gonadotropin levels were not correlated with AR immunoexpression levels in Sertoli cells and peritubular myoid cells. These results indicate that immunodetectability of the AR is not related to the condition of the spermatogenic epithelium in patients with oligozoospermia. Inappropriate expression of the AR is neither a cause nor a consequence of idiopathic infertility in the present group of patients.

High dose testosterone therapy for reduction of final height in constitutionally tall boys: does it influence testicular function in adulthood?

OBJECTIVE: We have studied the effect of treatment with high doses of androgens during puberty on testicular function in adult men with constitutionally tall stature, taking into account confounding factors interfering with sperm quality, since existing published data do not include whether testicular function is impaired by such treatment. DESIGN: Historical cohort study. PATIENTS: Forty-three previously androgen treated tall men (cases) and 30 non-treated tall men (controls). MEASUREMENTS: Physical examination, semen analysis and plasma levels of LH, FSH, testosterone (T), sex hormone binding globulin (SHBG) and inhibin. RESULTS: Sperm quality and testis volume were comparable between cases and controls. Mean sperm concentration was 66.4 x 10(6)/ml in cases and 66.2 x 10(6)/ml in controls. A left-sided varicocele was found in 45% of the cases and 37% of the controls. In cases we observed a significant effect of the age at start of androgen therapy on sperm motility (regr. coeff. (SE): 4.92 (2.41)%, P = 0.048). In addition, testicular size at start of therapy had a significant effect on sperm concentration (regr. coeff. (SE): 5.57 (1.54) x 10(6)/ml, P = 0.0012) and on total sperm count (regr. coeff. (SE): 43.1 (7.73) x 10(6), P = 0.0001). Plasma levels of T, SHBG and inhibin were not statistically different between the groups. Cases had significantly higher FSH levels (mean (SD) 3.3 (2.2) vs 2.1 (0.8) IU/I, P = 0.004) and significantly lower LH levels (mean (SD) 2.3 (0.9) vs 3.1 (1.4) IU/I, P = 0.019). We found a significant effect of age at start of therapy on plasma FSH level in the treated men (regr. coeff. (SE): -0.73 (0.18) IU/I, P = 0.0003). CONCLUSIONS: Treatment with high doses of androgens for reduction of final height in constitutionally tall stature has no long-term side-effect on sperm quality, testicular volume or plasma testosterone levels. However, treated men had significantly higher plasma levels of FSH compared with controls. The meaning of this difference remains to be established. Varicocele was present in 42% of the adult tall men.

Plasma levels of luteinizing hormone during hyperprolactinemia: response to central administration of antagonists of corticotropin-releasing factor.

Since high concentrations of prolactin (PRL) enhance the hypothalamic release of corticotropin-releasing factor (CRF), and CRF decreases the hypothalamic secretion of luteinizing hormone (LH)-releasing hormone (LHRH), it could be that CRF is involved in the suppressed secretion of LH during hyperprolactinemia. The aim of this study was to explore this possibility in hyperprolactinemic male rats. Hyperprolactinemia, induced by insertion of 3 pituitary glands under the kidney capsule, decreased plasma LH levels by 68% and caused a 2-fold increase in plasma corticosterone. Intracisternal administration of the CRF antagonist alpha-helical CRF(9-41) induced both in pituitary-grafted rats and in normoprolactinemic controls a 2 to 3-fold increase of LH in the plasma sample taken 1 h after injection of alpha-helical CRF(9-41). Plasma levels of LH in pituitary-grafted rats were 2-3 times higher during intracerebroventricular infusion for 7 days with CRF antiserum than during saline infusion. Furthermore, after infusion of CRF antiserum for 7 days into the lateral brain ventricle plasma LH levels had increased by 270% in normoprolactinemic male rats. These results indicate that hypothalamic CRF is involved in the control of LH release in male rats. To further investigate whether CRF is involved in the effect of PRL on LH secretion, we infused PRL, alone or together with CRF antiserum, for 7 days into the lateral brain ventricle of normoprolactinemic male rats. After 7 days of PRL infusion, LH levels had decreased by 45%, whereas plasma corticosterone was 150% higher. This action of PRL on LH and corticosterone was prevented when besides PRL also CRF antiserum was infused.(ABSTRACT TRUNCATED AT 250 WORDS)

Binding of epididymal proteins to rat spermatozoa in vivo.

The secretion of epididymal proteins and their binding to spermatozoa in rats were examined after retrograde perfusion of the superior and inferior epididymal arteries with [35S]methionine. PAGE revealed that the pattern of radioactive proteins in the luminal fluid was markedly different from the well-characterized pattern of secretory proteins obtained by in vitro incubation of epididymal minces with labeled methionine. Of the proteins secreted into the lumen, about 1% were associated with Percoll-purified spermatozoa. More proteins were associated with the spermatozoa in the corpus epididymidis than in the caput. Sequential extraction of spermatozoa with an isotonic buffer, a high-salt buffer, Triton X-100, and SDS revealed that almost half of the radiolabeled proteins could be extracted with the isotonic buffer. The firmly bound radioactive proteins remaining, which were extracted with Triton X-100 or SDS, consisted of one major band of 25 kDa and two minor bands of 30 kDa and 32 kDa. Analysis of the sperm-associated proteins at various times after the isotope was administered indicated that tight binding of proteins to spermatozoa occurs within 3 h after isotope injection.

Testicular regulation of epididymal protein secretion.

The effects of different androgen and testicular fluid levels on the protein synthesis and secretion of the epididymis of mice and rats were examined. In mice, the in vitro protein synthesis and secretion of five epididymal segments were measured from 3 days up to 8 weeks after efferent duct ligation. During the entire period, alterations in the rate of protein secretion per milligram tissue were small. At 8 weeks, the mean rate of protein synthesis per milligram ligated epididymal tissue was 80% of that of the control side. As a consequence of the weight loss of the ligated epididymis, however, the protein secretion per organ can be estimated to be reduced by 50%. Changes in the protein profile were only found in the proximal segment, where a 40-kd protein appeared and a 29-kd protein disappeared. In rats, the effects of efferent duct ligation were studied in vivo for up to 8 months. Structural changes were present both in the proximal and in the distal epididymis. The most conspicuous change in the protein profile of secretory proteins was the disappearance of a 27-kd protein from the proximal segment. In the distal epididymis, a 32-kd protein was no longer secreted. In mice, the effects of castration on the profile of secreted proteins demonstrated that, without androgen stimulation, some proteins are still secreted 6 weeks after castration. Administering low or high doses of testosterone propionate to castrated mice resulted in almost similar profiles of secretory proteins. However one protein secreted in the proximal epididymis was preferentially stimulated by the high dose of testosterone propionate.

Secretion and transport of mouse epididymal proteins after injection of 35S-methionine.

The presence of epididymal secretory proteins in crude luminal fluids of the epididymis of mice was investigated at varying times after i.v. injection of 35S-methionine or after incubation of epididymal minces with 35S-methionine. The amount of label incorporated into luminal proteins after in vivo injection was not significantly different at 4, 8, 12, and 16 h. The quantity of labeled proteins in the crude luminal fluids of Regions 1-3 (caput) was about two and four times higher than in Regions 4 (corpus) and 5 (cauda), respectively. Increasing the dosage of 35S-methionine strongly increased the amount of labeled protein present. Approximately half of the labeled protein present in the epididymis was found in the luminal fluid. Polyacrylamide gel electrophoresis revealed comparable patterns of proteins at 8 h after injection of isotope or after a 5-h in vitro incubation of minced epididymal tissues with isotope. The protein patterns from the five regions, however, were markedly different from each other and highly characteristic. Two proteins (25 kDa and 18 kDa) were found in crude luminal fluids of Regions 2 and 3 eight hours after in vivo injection, but not in Regions 4 and 5. One protein (29 kDa) was found in high amounts in Regions 4 and 5 eight hours after injection. Five days after injection, the three proteins were found in Regions 4 and 5. However, the 25-kDa protein was present in reduced amount, whereas the 18- and 29-kDa proteins accumulated in caudal fluid.(ABSTRACT TRUNCATED AT 250 WORDS)