Search PubMed⌕ Search

SEARCH · Search PubMed

Results for “EPIDIDYMITIS”

Search indexed PubMed citations on genomics, clinical trials, systematic reviews and public health. Explore titles, authors and supplied subject terms, then open the PubMed record.

Quote a phrase for an exact phrase match. Source license links do not imply unrestricted reuse.

At least 595 records · Page 33Linked to original sources

Comparative analysis of the ability of precursor germ cells and epididymal spermatozoa to generate reactive oxygen metabolites.

Male germ cells at various stages of differentiation from pachytene spermatocytes to mature caudal epididymal spermatozoa were examined for their ability to generate reactive oxygen species (ROS) using sensitive chemiluminescence techniques. In general, spermatozoa were found to spontaneously generate hydrogen peroxide as they progressed through the epididymis, maximal activity being observed on the release of mature cells from the caudal region into a modified Krebs-Ringer's solution. The spontaneous production of hydrogen peroxide rose rapidly during the first 10 min after the spermatozoa had been diluted into culture medium and thereafter stabilized, neither phorbol esters nor A23187 subsequently influencing this activity. Low levels of superoxide generation were also detected in suspensions of epididymal spermatozoa, but did not correlate with maturation status. However, superoxide production could be dramatically enhanced by the addition of exogenous NADPH, in a manner that was closely correlated with the stage of epididymal development being maximal for immature cells recovered from the caput epididymis in all species. Precursor germ cells (pachytene spermatocytes, round and elongate spermatids) similarly generated chemiluminescent signals compatible with the low level generation of ROS. Superoxide generation in these cells could again be stimulated by NADPH, via mechanisms that were inversely related to the stage of germ cell differentiation, the greatest activity being observed in pachytene spermatocytes. These results demonstrate that differentiating male germ cells have the potential to generate ROS, and have implications for the redox regulation of gonadal function and the development of reproductive pathologies involving oxidative stress.

Animals↗

Changes in binding of lectins to epididymal, ejaculated, and capacitated spermatozoa of the rhesus monkey.

BACKGROUND: The present study was undertaken to evaluate the changes in rhesus monkey sperm surface glycoconjugates during maturation, ejaculation, and capacitation in order to provide background information that would help in evaluating adverse effects, if any, caused by the use of contraceptive agents. METHODS: Adult sexually mature rhesus monkeys were castrated under ketamine anaesthesia. Percoll purified sperm from different epididymal segments and motile-ejaculated spermatozoa prior to and following in vitro capacitation were exposed to FITC-labeled lectins. Live or sperm prefixed with paraformaldehyde/alcohol were used. Quantitative analysis of changes in lectin binding was done immunoassay. RESULTS: The majority of live spermatozoa did not show binding of Con A and PNA, whereas uniform labeling of WGA to sperm from corpus epididymidis onward was seen. Unfixed spermatozoa showed marked variation in the pattern of lectin binding. The majority of spermatozoa fixed with paraformaldehyde or alcohol showed maximum lectin labeling over the acrosome, but the postacrosomal area invariably did not bind the lectins. Major changes in the localization of Con A, PNA, or WGA to prefixed spermatozoa were not seen during epididymal transit and in the ejaculate. In capacitated acrosome-reacted spermatozoa, Con A, PNA, and WGA were localized mainly in the equatorial segment. Binding of Con A and PNA was abolished by using lectins preincubated with appropriate inhibitor saccharides. Sperm, exposed to FITC-WGA preincubated with inhibitor sugar, did not show complete inhibition. Quantitative analysis of lectin binding by immunoassay showed increase in binding of lectins during epididymal transit with maximum binding in sperm from the corpus epididymidis. CONCLUSIONS: The variations in lectin labeling of live spermatozoa could be due to redistribution of sperm surface sugars or membrane damage. The changes in lectin labeling during maturation and capacitation may be associated with their role in ovum recognition and fusion.

Analysis of Variance↗

Effects of castration on thiol status in rat spermatozoa and epididymal fluid.

Mammalian spermatozoa gain their fertilizing ability as they mature in the epididymis, a process which is accompanied by oxidation of sperm protein thiols. Since sperm maturation is dependent upon normal androgenic support to the epididymis, the present work was designed to study the effects of castration on thiol status. Spermatozoa and epididymal fluid were isolated from the epididymides of male rats 5 days after castration or after 11 daily injections of the antiandrogen, cyproterone acetate. Spermatozoa and epididymal fluid were labeled with the fluorescent thiol labeling agent monobromobimane. Intact spermatozoa were evaluated by fluorescence microscopy, protein thiols were analyzed by electrophoresis, and fertilizing ability was examined after insemination of sperm suspension into the uterine horns of immature superovulated female rats. We found that both treatments resulted in an increase in cauda sperm thiols as shown by increased fluorescence in the intact spermatozoa. Protamines and nonbasic proteins were found to have increased levels of reactive thiols. The protein profiles of epididymal fluid from castrated rats were different from those of the controls, and the fluorescence patterns corresponded to the protein profiles. Our results indicate that testosterone withdrawal leads to inhibition of sperm thiol oxidation.

Androgen Antagonists↗

A maturation-related differential phosphorylation of the plasma membrane proteins of the epididymal spermatozoa of the hamster by endogenous protein kinases.

When the plasma membranes of caput and cauda epididymal spermatozoa of hamster were evaluated for their ability to undergo phosphorylation, a differential phosphorylation of the membrane proteins was observed. In the plasma membranes of the caput epididymal spermatozoa (immature), twelve proteins were phosphorylated (100, 76, 67, 65, 55, 52, 47, 42, 38, 32, 30, and 20 kD), whereas in the plasma membranes of cauda epididymal spermatozoa (mature), a differential phosphorylation pattern was observed with respect to the 94, 67, 52, and 47 kD proteins. The 94 kD protein was found to be phosphorylated and the 67 kD protein was found to be not phosphorylated in cauda spermatozoal plasma membrane (Cd SPM) in contrast to this protein in caput spermatozoal plasma membrane (Cpt SPM). The 52 and 47 kD proteins were also more intensely phosphorylated in Cd SPM than Cpt SPM. The 100 kilodalton protein, although present in both Cpt and Cd sperm plasma membranes, was found to be phosphorylated at the tyrosine residues only in the Cd SPM, as indicated by the Western blot using antiphosphotyrosine antibody. Further, a differential phosphorylation of the substrate proteins present in the Cpt and Cd SPM was seen when Mg2+ in the assay buffer was replaced by other divalent cations. For instance, Zn2+ stimulated the phosphorylation of an 85 kD protein in cauda SPM and not in the caput SPM and Ca2+ stimulated the phosphorylation of a 76 kD protein only in the cauda SPM. The phosphoproteins in both the plasma membranes were found to be phosphorylated predominantly at the tyrosine residue. The differential phosphorylation at a 100 kD protein at tyrosine in the Cd SPM (Western blot), which is absent in the immature Cpt SPM, also indicated that certain proteins in the hamster spermatozoa are phosphorylated in a maturation-specific manner.

Acrosome↗

Genomic organization and chromosomal localization of the murine epididymal retinoic acid-binding protein (mE-RABP) gene.

The murine epididymal retinoic acid-binding protein (mE-RABP) is specifically synthesized in the mouse mid/distal caput epididymidis and secreted in the lumen. In this report, we have demonstrated by Southern blot analysis of genomic DNA that mE-RABP is encoded by a single-copy gene. A mouse 129/SvJ genomic bacterial artificial chromosome (BAC) library was screened using a cDNA encoding the minor form of mE-RABP. One positive BAC clone was characterized and sequenced to determine the nucleotide sequence of the entire mE-RABP gene. The molecular cloning of the mE-RABP gene completes the characterization of the 20.5-kDa-predicted preprotein leading to the minor and major forms of mE-RABP. Comparison of the DNA sequence of the promoter and coding regions with that of the rat epididymal secretory protein I (ESP I) gene showed that the mE-RABP gene is the orthologue of the ESP I gene that encodes a rat epididymal retinoic acid-binding protein. Several regulatory elements, including a putative androgen receptor binding site, "CACCC-boxes," NF-1, Oct-1, and SP-1 recognition sites, are conserved in the proximal promoter. Analysis of the nucleotide sequence of the mE-RABP gene revealed the presence of seven exons and showed that the genomic organization is highly related to other genes encoding lipocalins. The mE-RABP gene was mapped by fluorescent in situ hybridization to the [A3-B] region of the murine chromosome 2. Our data, combined with that of others, suggest that the proximal segment of the mouse chromosome 2 may be a rich region for genes encoding lipocalins with a genomic organization highly related to the mE-RABP gene.

Amino Acid Sequence↗

CD52 mRNA is modulated by androgens and temperature in epididymal cell cultures.

Cultured rat epididymal tissue explants formed >90% pure, adherent growing epithelial cell monolayers. Despite their flattened and apparently androgen receptor-negative phenotype, these cells for a short period kept characteristics of the epididymal duct epithelium, i.e., expression of the tissue-specific marker CD52 and responsiveness of its mRNA toward temperature elevation and androgen withdrawal. When cells were grown on permeable supports at 33 degrees C, androgen supplementation or withdrawal specifically modulated the levels as well as the length of the CD52 mRNA. Elevation of the culture temperature to a quasi abdominal milieu of 37 degrees C selectively reduced the CD52 mRNA levels under all culture conditions. This reduction was not affected by the presence of androgens and was not accompanied by changes in length, suggesting that the modulation of CD52 mRNA in epididymal cells by androgens and by temperature is synergic, but may involve different molecular mechanisms. CD52 mRNA levels, however, were not stable in the primary cultures but decreased rapidly to undetectable levels after 4-5 days at all culture conditions. GAPDH mRNA levels, on the other hand, were stable throughout the culture period.

Androgens↗

Maturational changes of the CD52-like epididymal glycoprotein on cynomolgus monkey sperm and their apparent reversal in capacitation conditions.

A major epididymal secretory protein in men has a colinear cDNA sequence with lymphocyte CD52, a sialylated glycoprotein. Immunostaining and flow cytometric detection of cynomolgus monkey sperm CD52 during epididymal maturation showed increases from 20 to 85% stained sperm from the caput to the corpus with staining intensities doubled. Freshly prepared cauda sperm showed only 10% staining while they markedly increased in percentage and intensity of staining upon incubation at 37 degrees C under capacitating conditions, but not at 4 degrees C. Western blotting of proteins from fresh cauda sperm revealed no less antigen than corpus sperm. Staining of ejaculated sperm exhibited similar increases during incubation. Further washing with a high salt medium before staining to remove any electrostatically-bound molecules masking the antigen showed no effect. Incubation-induced increases in antigen binding were accelerated by the addition of neuraminidase (0.25 and 0.5 U/ml), but not affected by the sialyl residue-rich fetuin (5 mg/ml) competing for any endogenous neuraminidase. There were no concomitant decreases in the staining of sialic acid residues during capacitation-incubation. These findings suggest a cryptic antigen epitope site as a consequence of sperm maturation and subsequent re-exposure under capacitation conditions, but not due to the removal of sialic acid residues by endogenous neuraminidase. Involvement of endogenous proteases was also ruled out, as incubation in the presence of protease inhibitors did not hinder the increases but resulted in a dose-dependent enhancement in staining, suggesting some protease-sensitive unmasking process. In conclusion, the monkey epididymal secreted CD52 on sperm underwent changes in antigenic characteristics during sperm maturation which were reversed under capacitation conditions.

Alemtuzumab↗

Secretion of proteins and glycoproteins by perifused rabbit corpus epididymal tubules: effect of castration.

Protein synthesis in epididymal tissue of intact and castrated rabbits was studied after incubation of epididymal minces with [35S]-cysteine or [35S]-methionine and protein separation by two-dimensional gel electrophoresis. Regional differences in the pattern of protein synthesized were observed. Castration did not change overall protein synthesis, but it reduced these regional differences. The presence of 5 alpha-DHT in the culture medium of the proximal corpus epididymidis perfused for 24 hr did not increase overall protein synthesis in tubules from intact or castrated rabbits and did not reinitiate synthesis of the proteins that had disappeared after castration. The kinetics of glycoprotein synthesis and secretion were studied by light and electron microscopy autoradiography at 0.5, 2, 6, and 24 hr after exposure to [3H]-mannose, [3H]-fucose, and [3H]-glucosamine. Changes in the distribution of mannose- and glucosamine-labeled material indicated that the decline in grain density over the epithelium from 30 min to 24 hr coincided with an increasing reaction over the stereocilia border from 30 min to 2 hr and in the lumen from 2 to 24 hr. The distribution of fucose-labeled material indicated that the grain reaction over the epithelium declined more rapidly than with the mannose label. When the glucosamine-labeled sperm mass was released from the tubules, the labeled material was lost after the first washing, indicating that the glucosamine-labeled glycoproteins did not bind firmly to corpus spermatozoa within 24 hr. After castration, both mannose- and fucose-labeled materials migrated to the cell apex more rapidly than in the intact animal, but they were not released as readily into the lumen. The culture of epididymal tubules from castrated males with 5 alpha-DHT for 24 hr did not promote the release of either mannose- or fucose-labeled material into the lumen. However, testosterone given in vivo for 2 weeks restored secretion of mannose-labeled material into the lumen.

Animals↗

Morphological changes in the midpiece of wooly opossum spermatozoa during epididymal transit.

Several ultrastructural changes were found to occur in the midpiece region of wooly opossum spermatozoa during epididymal maturation. The changes include alterations in mitochondrial morphology, development of structural specializations of the plasma membrane, and acquisition of a prominent extracellular coating. The lamellar membrane network which is wound about the periphery of the mitochondria becomes more densely packed during sperm development and the reticular network of membranes noted in the center of the mitochondria of immature sperm disappears leaving a homogeneous electron dense central zone. During epididymal transit the plasma membrane over the sperm midpiece region shows extensive structural modification. In cross sections of paired spermatozoa the plasma membrane of the midpiece regions shows a very regular, repetitive scalloping. In longitudinal sections the scalloping is observed as continuous parallel ridges which extend slightly obliquely to the flagellar long axis. Each ridge appears to be greater in density than the interridge areas. In the epididymis a prominent extracellular coating of dense material is deposited over the midpiece surface; this material is similar in appearance to dense material seen in restricted areas of the epididymal lumen. At the proximal and distal ends of the midpiece the plasma membrane comes into intimate contact with underlying structural specializations and it is suggested that these zones of fusion may serve to preserve regional differences in membrane composition.

Animals↗

Ultrastructure of epididymal interstitial reactions following vasectomy and vasovasostomy.

The response of the male reproductive tract to vasectomy includes inflammation of the interstitial tissue of the epididymis. The pathogenesis of epididymal interstitial reactions and characteristics of the responding cells were studied by electron microscopy in Lewis rats at intervals following bilateral vasectomy, vasectomy followed 1 month later by vasovasostomy, or sham operations. In areas of interstitial reaction, numerous macrophages, monocytes, lymphocytes, neutrophils, and plasma cells occupied the connective tissue. Macrophages, containing many lysosomes and vesicles, aggregated and assumed the appearance of epithelioid cells. Processes of adjacent macrophages interdigitated with one another and closely approached the surfaces of lymphocytes. Many plasma cells with distended rough endoplasmic reticulum appeared in the interstitium. The majority of animals in the vasectomy and vasovasostomy groups exhibited epididymal interstitial changes by 2-3 months; the cauda epididymidis was the region most often affected. The ultrastructural features were indicative of chronic granulomatous inflammation and were consistent with an immune response that includes antigen presentation by macrophages to lymphocytes, lymphocyte differentiation, and local antibody production by plasma cells. The nearly complete absence of sperm or recognizable parts thereof in the interstitial tissue in the areas of the reactions suggests that these lesions formed in response to soluble antigens leaking from the duct. Vasovasostomy was not effective in reversing or retarding epididymal inflammation at the intervals studied.

Animals↗

Sclerotherapy for hydrocoele and epididymal cysts.

A prospective study was carried out on the efficacy of sclerotherapy for the treatment of hydrocoeles and epididymal cysts. Thirty-six hydrocoeles and 13 epididymal cysts were treated and followed up for between 1 and 2 years. Thirty-four hydrocoeles were cured, 1 failed to respond to treatment and 1 recurred after treatment. All 13 epididymal cysts were cured.

Adult↗

Similar biochemical properties of human seminal plasma and epididymal alpha-1,4-glucosidase.

We have studied some characteristics of alpha-1,4-glucosidases in human male reproductive organs in order to obtain information on the origin of the enzyme in seminal plasma. Acid and neutral enzymes could be distinguished on the basis of their selective inhibition either by SDS (acid enzyme) or MTT (neutral enzyme). Only the epididymis contained a significant amount of SDS resistant neutral alpha-1,4-glucosidase which was comparable to what has been isolated in seminal plasma. The similarity of epididymal and seminal plasma neutral enzymes was further confirmed by ultracentrifugation on sucrose density gradients, which permitted a complete separation of neutral (11S) and acid (4S) iso-enzymes. The 11S form was present in epididymis and in seminal plasma, but was totally absent in seminal vesicles, prostates and testis. The epididymal enzyme also had some of the unique characteristics found in the seminal plasma enzyme: it precipitated upon dialysis against distilled water, and its mobility on SDS polyacrylamide gel electrophoresis was identical to that of form 1 in seminal plasma. These results, although they do not constitute absolute proof of the identity of epididymal and seminal plasma alpha-glucosidase, certainly provide strong support for this hypothesis.

Adult↗

Growth and characterization of polarized monolayers of epididymal epithelial cells and Sertoli cells in dual environment culture chambers.

Epididymal epithelial cells isolated from mature rats and Sertoli cells isolated from 10-day-old rats were cultured in serum-free defined media on extracellular matrix impregnated filters maintained in dual environment culture chambers. Epididymal epithelial cells had a polarized appearance only when plated at high density (greater than 1 X 10(6) cells/cm2). Confluent monolayers of these cells formed a permeability barrier to inulin. Sertoli cells were columnar and highly polarized when grown on extracellular matrix-impregnated filters, cuboidal when grown on filters alone, and squamous when grown on plastic. Confluent polarized monolayers of these cells excluded the electron-dense tracer lanthanum nitrate by way of basal-tight junctions. Therefore, polarized monolayers of epididymal epithelial cells and Sertoli cells can be obtained by growing the cells at high density on extracellular matrix-impregnated permeable supports. By maintaining the monolayers in specially constructed culture chambers, the cells can develop a permeability barrier, and are able to achieve the separation of apical from basal compartments so important for their function in vivo.

Animals↗

Effect of corticosterone on rat epididymal lipids.

Corticosterone-induced changes in serum hormone profiles and the lipid composition of the caput and cauda epididymidis were studied. The analysis was conducted in both unwashed and washed (free from fluids and spermatozoa) epididymal tissues. Corticosterone treatment significantly depressed serum prolactin and testosterone but gonadotropins were unaltered. In the unwashed caput region, lipid analysis showed a significant decrease in total lipids, as well as in cholesterol, phospholipid, and the phosphatidyl inositol, phosphatidyl choline, and phosphatidyl ethanolamine fractions. However, in the unwashed cauda region, the total lipid and cholesterol content was not altered while total phospholipid and phospholipid fractions were significantly decreased. On the other hand, in the washed caput and cauda regions, corticosterone induced a significant increase in total lipid, glyceride, and the mono, di, and triglyceride fractions, leaving total phospholipid and its fractions unaltered. Following 20-day withdrawal of corticosterone treatment, all lipid classes returned to normal along with serum hormone profiles. Our findings imply that an excess of corticosterone influences epididymal lipids. These changes in the epididymal lipid pattern probably are reflected in fertility disorders in patients with glucocorticoid excess.

Animals↗

Effects of thawing procedure on postthawed in vitro viability and in vivo fertility of red deer epididymal spermatozoa cryopreserved at -196 degrees C.

In this study, we have determined the effects of individual factor and thawing procedure on in vitro viability and in vivo fertility of frozen-thawed red deer epididymal spermatozoa. The spermatozoa that were collected from 13 Iberian deer stags were diluted at room temperature in a Triladyl-20% egg yolk medium and frozen in nitrogen vapors. In the first experimental series, sperm samples were collected from 10 mature stags. For thawing, the frozen straws were subjected to 3 different procedures: I (37 degrees C for 20 seconds), II (60 degrees C for 8 seconds) and III (70 degrees C for 5 seconds). Sperm cryosurvival was judged in vitro by microscopic assessments of individual sperm motility (SM) and of plasma membrane and acrosome (NAR) integrities. Statistically significant variations were found (P <.05) between stags for most of the seminal parameters evaluated. The thawing procedure did not have an effect on the seminal characteristics evaluated after this process, except for SM (P <.05), with the best overall recovery rates after freezing and thawing found with the use of protocol I. Our results also show a differential resistance to return to isosmotic conditions of spermatozoa thawed using the different thawing protocols. In the second experimental series (insemination artificial trial), with spermatozoa from 3 stags, results of fertility were statistically higher (69.7% vs 42.4%, P =.014) when spermatozoa were thawed at 37 degrees C for 20 seconds than were warmed at 60 degrees C for 8 seconds. Therefore, thawing protocol I, which provides slow thawing rates, was the most beneficial for epididymal spermatozoa thawing of the cervid subspecies analyzed in this study. In summary, high in vitro survival and in vivo fertility of frozen-thawed deer epididymal spermatozoa were dependent on warming rates, but each stag exhibited its own sensitivity to cryopreservation.

Animals↗

Recapitulation of germ cell- and pituitary-specific expression with 1.6 kb of the cystatin-related epididymal spermatogenic (Cres) gene promoter in transgenic mice.

The Cres (cystatin-related epididymal spermatogenic) gene encodes the defining member of a new subgroup within the family 2 cystatins of cysteine protease inhibitors. Cres expression is highly tissue- and cell-specific, with messenger RNA (mRNA) present in the testicular round/elongating spermatids, proximal caput epididymal epithelium, gonadotroph cells in the anterior pituitary gland, and corpus luteum of the ovary. To begin to elucidate the molecular mechanisms controlling the tissue- and cell-specific expression of the Cres gene, transgenic mice were generated containing 1.6 kilobases (kb) of the mouse Cres promoter linked to the bacterial chloramphenicol acetyltransferase (CAT) reporter gene. A CAT enzyme-linked immunosorbent assay detected CAT protein in the testis, epididymis, isolated cauda epididymal spermatozoa, and anterior pituitary gland from mice heterozygous and homozygous for the transgene. However, reverse transcription (RT)-PCR did not detect CAT mRNA in any regions of the epididymis, suggesting that the CAT protein detected in the epididymis was from spermatozoa. RT-PCR also did not detect CAT mRNA in the ovary. RT-PCR analysis of the testes from mice of different postnatal ages showed CAT mRNA first detected at day 22, which correlated with the first appearance of Cres mRNA and with the presence of round spermatids. These studies demonstrate that 1.6 kb of Cres promoter contains the DNA elements necessary for germ cell and pituitary gland-specific expression but lacks critical sequences necessary for expression in the epididymis and ovary.

Animals↗

Glycoprotein secretions of the epididymis in the rabbit and hamster: localization on epididymal spermatozoa and the effect of specific antibodies on fertilization in vivo.

To assess the functional significance of glycoprotein secretions of the rabbit and hamster epididymis during sperm maturation and fertilization, antibodies have been raised against acidic protein fractions isolated from epididymal fluid. Specific antiserum was elicited against each of three rabbit glycoproteins designated R1, R2, and R3 with isoelectric points of pI 3.45, 4.15, and 4.65 respectively, and against one hamster glycoprotein (Hl), pI 3.40. Epididymal glycoproteins on the surface of washed spermatozoa from various regions of the epididymis were localized by the fluorescent antibody technique and by sperm agglutination with antiserum. They were first detected on restricted regions of spermatozoa from the distal caput and corpus epididymidis and each antigen had a characteristic binding pattern. The effect of specific antibodies on fertilization in vivo was tested in rabbits by preincubating cauda epididymal spermatozoa with heat-treated antiserum or univalent immunoglobulin fragments before their deposition into oviducts of does induced to ovulate. In all cases, fertilization rates were significantly reduced (P less than or equal to 0.05) compared with controls, the most effective antiserum being against glycoprotein antigen R1 found only on the anterior acrosome of spermatozoa. Heat-treated antiserum against H1 glycoprotein placed in the bursal cavity of ovulating females significantly inhibited fertilization in the hamster (P less than or equal to 0.005). These results are discussed in relation to the modification to the sperm plasmalemma during maturation.

Animals↗

Distribution of a proteinase inhibitor of epididymal origin in the tissues and secretions of the male reproductive tract of mice.

Monoclonal antibodies to a low molecular weight, acid-stable acrosin-trypsin inhibitor isolated from epididymal homogenates were used to localize the inhibitor in tissues and secretions of the male reproductive tract of mice. The inhibitor, identified by indirect immunofluorescence, is present in the testes and in the apical portion of the epithelial cells from the caput region of the epididymis of both intact and efferentiectomized animals. Sperm isolated from the testes and caput epididymal region show inhibitor-positive fluorescence on the anterior acrosomal region. The inhibitor could not be localized on ductus or electroejaculated sperm or ductus sperm previously incubated in a purified inhibitor solution. Furthermore, the inhibitor was not visible in the copulatory plug of recently inseminated animals or on sperm recovered from the uterus or from an artificial capacitating medium. The inhibitor could be detected by an enzyme-linked immunosorbent assay in the supernatants of detergent treated or frozen-thawed caput sperm but not of ductus sperm. The data suggest that the inhibitor, made in both the testes and caput epididymis where it associates with the sperm, is lost from the sperm or irreversibly masked during the epididymal sojourn.

Animals↗