Major contribution of epididymis to alpha-glucosidase content of ram seminal plasma

Acid alpha-glucosidase and L-carnitine (a well-known epididymal marker) were measured in rete testis and epididymal fluids of adult male rams. These fluids were collected by selective catheterization or by a micropuncture technique, respectively. Both parameters remained at a low and constant level in rete testis and all along caput and corpus epididymidis. Then they increased at equivalent rates in cauda epididymidis to much higher levels than those in seminal plasma (5 mU/mg protein and 10 mM, respectively). An optimum pH study of alpha-glucosidase activity in these fluids showed two well-separated peaks in rete testis and caput epididymal fluids around pH 4 and 7, respectively, but only a single peak at pH 4 in cauda epididymidis that was comparable to the one in seminal plasma. Sucrose density gradient fractions analyzed for their enzyme content in the absence or presence of sodium dodecyl sulfate (1% w/v), a selective inhibitor of acid alpha-glucosidase activity, allowed the demonstration of two enzyme forms at pH 6.8 in rete testis fluid sedimenting in the 7S and 4S regions of the gradient, while a unique 4S form was encountered in cauda epididymidis and in seminal plasma. Although the fate of the minor 7S component of the rete testis fluid in its epididymal transit is presently unknown, similarities between the enzyme in cauda epididymidis and seminal plasma are strong enough to support the hypothesis that epididymis contributes primarily to the acid alpha-glucosidase content of ram seminal plasma.     

Changes in protein composition of the luminal fluids along the epididymis of the tammar, Macropus eugenii

Micropuncture samples of luminal fluid were collected from the rete testis and along the epididymis. Quantitative analyses showed that the ductuli efferentes reabsorb about half the protein leaving the testis. Considerable protein is secreted by the caput epididymidis (initial segment) and there is a net loss of protein from the corpus and cauda epididymidis. Denatured, polyacrylamide gel electrophoresis showed that there are 5 proteins in rete testis fluid which are not present in blood (Mr of 14,700, 22,800, 24,100, 43,000 and 44,800). One of these proteins (Mr 14,700) is lost from plasma in the ductuli efferentes and 2 (Mr 43,200 and 44,800) are lost in the corpus epididymidis. Twelve proteins appear in the epididymal plasma and are not present in rete testis fluid or blood: 6 appear in the caput epididymidis (Mr 30,000, 31,000, 32,300, 17,400, 18,700 and 21,400), 3 in the corpus epididymidis (Mr 12,800, 39,800 and 90,600) and 3 in the cauda epididymidis (Mr 10,900, 56,300 and 63,000). A protein with the same molecular weight as a blood protein (149,500) accumulates in the corpus and cauda epididymidis. None of the samples of luminal fluid contained particulate matter other than spermatozoa, indicating that the tammar is a useful animal for micropuncture studies.     

Evidence for the presence of oxytocin in the ovine epididymis

The testes of several species contain oxytocin and/or neurophysin, but the content or localization of oxytocin in epididymal tissue has not been studied. The present study was undertaken to localize oxytocin and neurophysin in epididymal tissue of the ram, and to quantify oxytocin in the ductus epididymidis and fluids entering and leaving the ductus epididymidis. Neurophysin was not detected in the epididymis; thus, synthesis of oxytocin by the epididymis is unlikely. Immunohistochemical localization of oxytocin was confined to the epithelium and capillaries. Oxytocin immunostaining was most intense for epithelium of the caput and declined in corpus and cauda regions. However, based on radioimmunoassay, no difference in oxytocin concentration was detected among regions of the epididymis. Since rete testis fluid entering and cauda epididymal fluid leaving the epididymis contained at least fourfold more oxytocin than testicular venous plasma, it was concluded that regional differences in epithelial concentration of oxytocin may have been masked by oxytocin contained in the luminal fluid. It was concluded further that the epididymis of the ram does not synthesize oxytocin, but about 22 ng/day enters the epididymis in rete testis fluid. Most of this luminal oxytocin apparently is absorbed by the epithelium of the caput epididymidis, with additional adsorption in the corpus and cauda. Although a role for oxytocin in ductal contractility cannot be excluded, it is more likely that the luminal oxytocin influences epithelial or sperm function.     

5alpha-Reductase and 3alpha-hydroxysteroid oxidoreductase enzyme activities in epididymis and their control by androgen and the rete testis fluid

The 5alpha-reductase and 3alpha-hydroxysteroid oxidoreductase enzyme activities have been measured in epididymal tissues and the control of these activities by androgens and the rete testis fluid appreciated. The highest 5alpha-reductase enzyme activity was found in the caput, the lowest in the corpus epididymidis. Androgens have a positive control on the 5alpha-reductase but no effect on the 3alpha-hydroxysteroid oxidoreductase activity. Ligation of the efferent ducts decreased significantly both enzyme activities in the caput but not in the corpus or in the cauda epididymidis.     

The concentration of carnitine in the luminal fluid of the testis and epididymis of the rat and some other mammals.

Luminal fluid was collected by micropuncture techniques from the testis and epididymis of the rat, hamster, rabbit, boar and ram and the concentration of free L-carnitine in the fluid was estimated using enzymic methods. Carnitine was present in the testicular fluid of the rat in concentrations less than 1 mM but increased down the epididymis to reach 53 mM in luminal fluid from the cauda epididymidis, approximately 2000 times higher than in blood plasma. A high concentration was first found in the luminal fluid from the distal caput epididymidis, at about the point where the spermatozoa become motile. Carnitine was also present in the epididymal luminal fluid of the other species studied; the amounts were not as high as those in the rat but were still higher than those in blood plasma.     

Regulation of the elemental composition of the epididymal fluids in the tammar, Macropus eugenii

Micropuncture, microanalytical and microelectrode techniques were used to study electrochemical aspects of 7 elements and fluid in the ductuli efferents and ductus epididymidis of the tammar. Rete testis fluid was isosmotic with blood and had a lower pH. It also contained lower concentrations of bicarbonate, sodium, calcium, magnesium, phosphorus and sulphur and higher concentrations of potassium and chloride than blood. The luminal fluid was acidified further during passage through the sperm ducts and all of the elements which were studied moved in or out of the lumen, usually against an electrochemical gradient. The ductuli efferents reabsorbed 87% of the fluid leaving the testis without changing the intraluminal concentrations of sodium, potassium and calcium, but the concentrations of magnesium, phosphorus and sulphur increased. The caput epididymidis reabsorbed about half the fluid entering it: sodium concentrations decreased and those of potassium and phosphorus increased. There was also some fluid reabsorption and an increase in the values of potassium and phosphorus in the corpus epididymidis. There was little net transport of fluid in the cauda epididymidis; sodium, chloride, magnesium and phosphorus concentrations decreased and potassium values increased. Studies involving filtration through a dialysis membrane of blood and fluid from the rete testis and cauda epididymidis showed that, whilst some of the calcium, magnesium, phosphorus and sulphur was associated with high molecular weight compounds in blood, the association was not significant in the reproductive fluids.     

Maturation and regulation of the motility of spermatozoa in the epididymis of the tammar wallaby (Macropus eugenii).

Demembranated spermatozoa from the rete testis developed vigorous flagellation when reactivated with ATP, but showed no forward progression such as that seen in samples from the cauda epididymidis. The proportion of spermatozoa that were reactivated was smaller for samples from the rete testis than from the cauda epididymidis. Studies in vitro of undiluted micropuncture samples from the epididymis indicated that the activity of spermatozoa is suppressed as they develop the capacity for motility. However, as spermatozoa spontaneously became activated during the collection or subsequent incubation of undiluted samples, it was concluded that the suppressive action is labile. The activity of spermatozoa in vitro was examined in diluted samples from the cauda epididymidis. A concentration of 2.5 mmol extracellular calcium/l was better than lower concentrations. Diluents at pH 5.5 completely inhibited sperm motility when they contained 20 mmol lactate/l (but not glutamate) and the effect was reversed by readjusting the diluent to pH 7.4. However, lactate was not considered to suppress sperm motility in situ, as the plasma from the cauda epididymidis contained only 2.7 +/- 0.5 mmol lactate/l. There was no effect of sodium concentration (1 and 115 mmol/l), pH (5.5 and 7.4) or amiloride (0 and 1 mmol/l) on sperm motility, indicating that motility is not dependent on the concentration of sodium above 1 mmol/l or on a sodium-proton exchange system. The relative viscosity of plasma from the cauda epididymidis did not affect the motility of spermatozoa.     

A Comparative Study on the Chemical Composition of Plasma from the Cauda Epididymidis,Semen Fractions,and Whole Semen in Boars

A comparative study was carried out on the chemical composition of plasma from the cauda epididymidis, semen fractions, and whole semen of boars. A total of 22 boars were used in this study. The boars, which ranged in age from 8 to 14 months, were of Swedish Landrace and Swedish Yorkshire breed. All boars used presented a normal semen picture. A dummy sow and an artificial vagina were employed for semen collection. The semen was collected as whole semen and as semen fractions in 10 nil volumes. The contents of the cauda epididymidis was removed post mortem. The following parameters were investigated: sperm concentration, dry weight of spermatozoa and of seminal plasma, osmotic pressure, sodium, potassium, chloride, inorganic phosphorus, calcium, magnesium, total protein, GOT, GPT, and alkaline phosphatase in seminal plasma. Paper electrophoresis was carried out on seminal plasma. Tlxe results of the analysis are summarized in Tables 1–6. The sperm concentration was approximately 3.2 mill./mm3 in the cauda epididymidis, 1 mill./mm3 in the sperm-richest fraction (II) and 0.25 mill./mm3 in whole semen. The dry weight (expressed in per cent dry matter) of spermatozoa was highest in the cauda epididymidis (25.47 %), showing a tendency to decreasing in semen fractions I—IV and was lowest in whole semen (15.29 %). The per cent dry weight in plasma was higher in the cauda epididymidis (4.56 %) than in semen fraction I (2.20 %). In semen fractions I—IV the per cent dry weight rose from 2.20 (U to 4.51 % and reached the level of approximately 3.80 % in the sperm-free fractions V—VII. The osmotic pressure was significantly higher in the cauda epidi-dymal plasma than in the whole seminal plasma or the seminal plasma fractions. The same phenomenon was observed in a boar where the cauda epididymal content was collected in vivo from a patent established fistula. There appears to be a connection between the per cent dry weight of spermatozoa and the osmotic pressure, which means that the per cent dry weight of the cauda epididymal spermatozoa decreases when mixed with the accessory gland secretions, which have a lower osmotic pressure. The fall in per cent dry weights is thought to be caused by an intake of water. The amount of sodium, chloride and magnesium was higher in ejaculated seminal plasma than in cauda epididymal plasma. The reverse was true for inorganic phosphorus and potassium. Moreover the sperm-free fractions contained more sodium, chlorides and magnesium than the sperm-containing fractions, while the concentration of potassium and inorganic phosphorus was comparatively higher in the sperm-containing fractions. A connection is apparent between sperm concentration and the potassium, inorganic phosphorus and magnesium levels. Statistical analysis of the values of chloride and magnesium revealed significant differences between individual boars for most of the semen fractions. The concentration of plasma proteins in the cauda epididymidis was approximately the same as in whole semen and in the semen fractions except for fraction I, which contained a relatively low concentration. As regards total protein there were significant differences between individual boars in most of the semen fractions as well. The paper electrophoretic pattern of epididymal plasma was different from that of semen plasma. Thus there were three or four distinct components in the cauda epididymidis numbered 1, 2, 3, and 4, and three distinct components in whole seminal plasma numbered 3, 4, and 5, while the sperm-richest semen fractions contained four components (2, 3, 4, and 5) and the others three components, namely 3, 4, and 5. The level of GOT was high in the cautlu cpiflidymill contents (99.1 i. u./ml) compared with that for whole seminal plasma (99.1 i.u/ml). In semen fractions there was a clear positive correlation between the level of GOT and the sperm concentration. The GPT concentration wis as a whole low and. in contrast to GOT. somewhat higher in the sperm-free fractions than in the sperm-containing fractions. The concentration of alkaline phosphatase was very high in cauda epididymal plasma (31,463 i. u./ml) as well as in the sperm-rich fractions (e.g. 7,096 i. u./ml in fraction II). Preliminary investigation has moreover revealed a very low alkaline phosphatase concentration in seminal plasma of vasectomized boars, which condition suggests thai the main origin for alkaline phosphatase in boars is the testis and epididymis.     

Beta-galactosidase in the seminal plasma and reproductive organs of the bull

The distribution of beta-galactosidase activity was studied in different reproductive organs, seminal plasma and spermatozoa of the bull. The highest specific activity of beta-galactosidase was found in testis and in different parts of the epididymis, where the activity seemed to be partly in secretory (cauda secretion) and partly in non-secretory, bound form (caput to cauda epididymidis). Gel filtration on Sepharose 6B at pH 7.0 revealed two beta-galactosidase forms (GF-1, Mr approximately 500,000-600,000 and GF-2, Mr approximately 190,000-220,000) in reproductive organs and seminal plasma. The pH-optimum of both beta-galactosidase forms was about 3.75-4.75. Hg2+ and p-chloromercuribenzoate inhibited strongly these activities. Further, form GF-2 seemed to be slightly more sensitive to the thermal inactivation at 50-70 degrees C than form GF-1. In chromatofocusing beta-galactosidase activities in bull seminal plasma coeluted with those of the cauda epididymidis (pI-values 7.5-6.4). On the contrary, prostate, Cowper's gland, testis, ampulla and seminal vesicles had enzyme activities eluting at lower pI-values (6.3-4.2). Thus, the seminal plasma activity is mainly an indicator for the function of the epididymal cauda.     

Sperm maturation, fluid transport, and secretion and absorption of protein in the epididymis of the echidna, Tachyglossus aculeatus

Extratesticular sperm maturation in the echidna mainly occurs in the initial segment of the ductus epididymidis. The process involves the development of motility, migration and loss of the cytoplasmic droplet, a decrease in permeability to Congo red and the formation of sperm bundles. The spermatozoa are supported in the bundles by a matrix of electron-dense material; the bundles are very motile is undiluted samples of luminal fluids. Micropuncture studies of anaesthetized echidnas showed that the ductuli efferentes absorb 74% of the fluid and 46% of the soluble protein that enters them. The initial segment of the ductus epididymidis absorbs 83% of the fluid which enters it, and its secretions increase the concentration of protein in luminal fluid by 107%. Denatured, linear-gradient polyacrylamide gel electrophoresis of micropuncture samples showed that 1 protein (apparent M4 = 100 500) which is not present in blood plasma is present in rete testis fluid, and a glycoprotein which is present in rete testis fluid (apparent Mr = 78500) is absorbed by the ductuli efferentes. Six proteins which are not present in blood plasma are secreted into the initial segment of the ductus epididymidis; 5 are glycoproteins (apparent Mr = 48500, 39000, 32000, 20500 and 19000) and one (apparent Mr = 82500) is not. The most prominent electrophoresis bands corresponded to the glycoproteins with apparent molecular weights of 48500, 20500 and 19000.     

Changes in lipase and phosphatase activities of rat spermatozoa in transit from the caput to the cauda epididymidis.

Rat spermatozoa from the cauda epididymidis, freed from their cytoplasmic droplets and acrosomes, were found to have a lower lipid content and to incorporate [14C]glucose into their glycerides and glycerophosphatides at a lower rate than spermatozoa from the caput epididymidis. Against the background of the activities of some glycolytic enzymes which remained constant the activity of alkaline phosphatase decreased in spermatozoa migrating through the epididymis, whereas the activity of monoglyceride lipase increased. The corresponding enzyme activities of non-flagellate germ cells of the testis were measured for comparison. The triglyceride lipase of non-flagellate germ cells and of spermatozoa from both caput and cauda epididymidis was activated by cyclic 3':5'-AMP.     

Changes in the protein composition of rat spermatozoa during maturation in the epididymis

Spermatozoa from the testis and cauda epididymidis were solubilized by detergent treatment and electrophoresis on SDS polyacrylamide gels revealed that the relative amounts of 13 detergent-extractable proteins decreased during passage of spermatozoa through the epididymis, 6 increased, whilst the remainder showed little or no change. Lactoperoxidase-catalysed iodination of plasma membrane proteins showed that the components carrying most of the label in testicular spermatozoa had Mr values of 110 000, 94 000, 84 000, 55 000 and 42 000 whereas on cauda epididymal spermatozoa the Mr values were 47 000, 24 000, 17 000, 14 500 and 13 500. Substantial differences were also noted in the protein composition of rete testis fluid and cauda epididymal plasma. The results support the concept that there is a considerable reorganization of the molecular architecture of the plasma membrane of spermatozoa during maturation in the epididymis.     

beta-N-acetylglucosaminidase in the reproductive organs and seminal plasma of the bull

The highest specific activity of beta-N-acetylglucosaminidase (beta-NAG) was found in the different parts of the epididymis, where the activity seemed to be partly in secretory and partly in non-secretory, tissue-bound form. Epididymal spermatozoa also contained moderate beta-NAG activity. The beta-NAG was separated by chromatofocussing and anion exchange chromatography with HPLC into multiple forms with distinct pI values (8.0-4.0). The cauda epididymidis, ampulla and the seminal vesicles formed the major secretory sources of the high beta-NAG activity in bull seminal plasma. The major secretory forms of beta-NAG in caput and cauda epididymidis showed distinct elution profiles. In the fractionation with gel filtration on Sepharose 6B, the beta-NAG activities derived from bull testis and caput epididymidis had smaller molecular weights than did the secretory enzymes in seminal plasma, seminal vesicle secretion and cauda epididymidis. Maximum activity of all beta-NAG isoenzymes was observed at pH 5.0. They were almost totally inactivated at 60 degrees C and about 75-80% of the activity was lost at 55 degrees C. All the isoenzymes were strongly inhibited by thiol reagents but not with other metal ions and chelating agents. Histochemical studies showed a strong granular (lysosomal) reaction for beta-NAG in basal cells and basal parts of the principal cells in all but the initial segment of the epididymis. An apical (secretory) reaction was prominent in the distal caput and corpus as well as in distal cauda. After the distal caput the luminal sperm mass became increasingly mixed with a beta-NAG-positive material. The epithelial cells of the ampulla and seminal vesicle displayed a moderate apical (secretory) reaction.     

Transport of IgG across the blood-luminal barrier of the male reproductive tract of the rat and the effect of estradiol administration on reabsorption of fluid and IgG by the epididymal ducts

In rats immunized systemically with tetanus toxoid the concentration of specific anti-tetanus-toxoid-specific IgG in fluid from the rete testis and cauda epididymidis were respectively 0.6% and 1.4% the concentration in blood serum. The extratesticular duct system reabsorbed 97% of the IgG and 99% of the fluid leaving the rete, but estradiol administration affected the site of reabsorption. In untreated rats, the ductuli efferentes reabsorbed 94% of the IgG and 96% of the fluid leaving the rete, whereas estradiol-treated rats reabsorbed 83% of the IgG and 86% of the fluid, and the ductus epididymidis fully compensated for these different effects of estradiol on the ductuli efferentes. The concentrations of IgG in secretions of the seminal vesicles and prostate gland were lower (0.1% and 0.3% respectively of the titers in blood serum) than in fluids from the extratesticular ducts, and were not affected by the administration of estradiol. RT-PCR showed that Fcgrt (neonatal Fc receptor, also known as FcRn) is expressed in the reproductive ducts, where IgG is probably transported across epithelium, being particularly strong in the ductuli efferentes (where most IgG was reabsorbed) and distal caput epididymidis. It is concluded that IgG enters the rete testis and is concentrated only 2.5-fold along the extratesticular duct system, unlike spermatozoa, which are concentrated 95-fold. Further, the ductus epididymidis can recognize and compensate for changes in function of the ductuli efferentes.     

过氧化物酶6在大鼠附睾中的表达及分布

通过双向电泳结合质谱技术分离鉴定正常成年大鼠附睾头段与尾段管腔液中的蛋白组成,从附睾头段及尾段管腔液的22个差异蛋白点中鉴定出12个蛋白质.其中11个蛋白质在不同种属哺乳动物的附睾组织中已有鉴定报道,而过氧化物酶6(peroxiredoxin 6,Prdx6)为新发现的存在于附睾头段及尾段管腔液中的体液蛋白.采用RT-PCR、Western印迹及免疫组化技术,对该蛋白在大鼠附睾中的表达及分布进行了分析.实验表明,Prdx6与精子的成熟、贮存及保护有一定关系,其具体机制值得进一步深入研究.     

A 105- to 94-kilodalton protein in the epididymal fluids of domestic mammals is angiotensin I-converting enzyme (ACE); evidence that sperm are the source of this ACE

SDS-PAGE analysis of luminal fluid from the ram testis and epididymis revealed a protein of about 105 kDa in the fluid in the caput epididymal region. The molecular mass of this fluid protein shifted from 105 kDa to 94 kDa in the distal caput epididymidis and remained at 94 kDa in the lower regions of the epididymis. The possible sperm origin of this protein was suggested by the decrease in intensity of a 105-kDa compound on the sperm plasma membrane extract and by its total disappearance from the fluid of animals with impaired sperm production caused by scrotal heating. The 94-kDa protein was purified from ram cauda epididymal fluid, and a rabbit polyclonal antiserum was obtained. This antiserum showed that membranes of testicular sperm and sperm from the initial caput were positive for the presence of an immunologically related antigen. The protein was immunolocalized mainly on the flagellar intermediate piece, whereas in some corpus and caudal sperm, only the apical ridge of the acrosomal vesicle was labeled. The purified protein was microsequenced: its N-terminal was not found in the sequence database, but its tryptic fragments matched the sequence of the angiotensin I-converting enzyme (ACE). Indeed, the purified 94-kDa protein exhibited a carboxypeptidase activity inhibited by specific blockers of ACE. All the soluble seminal plasma ACE activity in the ram was attributable to the 94-kDa epididymal fluid ACE. The polyclonal antiserum also showed that a soluble form of ACE appeared specifically in the caput epididymal fluid of the boar, stallion, and bull. This soluble form was responsible for all the ACE activity observed in the fluid from the distal caput to the cauda epididymidis in these species. Our results strongly suggest that the epididymal fluid ACE derives from the germinal form of ACE that is liberated from the testicular sperm in a specific epididymal area.     

Resorption versus secretion in the rat epididymis

Micropuncture samples were taken from the rete testis, caput epididymidis and cauda epididymidis of anaesthetized adult rats and assayed for total protein, sodium and potassium concentrations. Intraluminal sperm concentrations were determined and used to calculate the amount of fluid resorbed from the efferent duct and epididymal lumen. It was demonstrated that large amounts of protein (30.2 mg/ml cauda volume) and sodium (241.8 mequiv./l) and smaller amounts of potassium (19.4 mequiv./l) are resorbed from the rat epididymal lumen between the caput and corpus epididymidis. This occurs despite increases in intraluminal concentrations of protein (from 22 to 28 mg/ml) and potassium (from 16 to 50 mequiv./l). Resorption is an important aspect of epididymal control of the intraluminal environment.     

Immunolocalization of clusterin in the ram testis, rete testis, and excurrent ducts

Clusterin, a glycoprotein that elicits cell aggregation, has previously been isolated from ram rete testis fluid, and has been partially characterized. In experiments reported, we have used monoclonal antibodies against clusterin in combination with indirect immunofluorescence microscopy to investigate the distribution of clusterin in the adult ram testis, rete testis, and excurrent ducts. Tissue blocks (5 mm3) were fixed in periodate/lysine/paraformaldehyde containing 0.1% glutaraldehyde and, after embedding, 5-microM sections were prepared for immunolocalization. In the testis, 2 basic patterns were observed: 1) strong to moderate staining for clusterin in the adluminal region with little staining in the basal region of the seminiferous epithelium and germinal cells; and 2) moderate staining throughout the seminiferous epithelium between germinal cells. In the rete testis, strong clusterin staining was localized intracellularly in the rete epithelial cells, most often associated with the luminal surface. In the epididymis, intracellular clusterin was localized in some principal cells of the caput epididymidis. The luminal surfaces and spermatozoa within the lumen were strongly positive. In the vas deferens, clusterin staining was associated with the luminal surface only. The presence of clusterin was clearly detected in unwashed isolated epididymal spermatozoa, but not in spermatozoa washed with phosphate-buffered saline containing 0.05% Tween 20.     

Distribution of 5 alpha-reductase in the epididymis of the tammar wallaby (Macropus eugenii) and dependence of the epididymis on systemic testosterone and luminal fluids from the testis

The activity of 5 alpha-reductase was much higher in the caput and corpus epididymidis than in the cauda epididymidis. Orchidectomy caused a reduction in 5 alpha-reductase activity in the caput and corpus epididymidis, and regression of the epithelium and reduction in mass of all regions of the epididymis. Subsequent testosterone therapy caused a substantial increase in amount of epithelium and overall mass of the cauda epididymidis but showed little or no increase in any of the responses measured in the caput and corpus epididymidis. We concluded that the caput and corpus epididymidis of the tammar respond to factors other than testosterone, probably some constituent in the luminal fluid, and therefore are homologous with the initial segments of the epididymis in eutherians.     

The histochemical localization of prostaglandin synthetase activity in reproductive tract of the male rat.

PG synthetase activity was assessed histochemically in the reproductive tract of male rats. Moderate activity was observed in tails of spermatozoa within the corpus and cauda epididymidis but there was no activity in the caput epididymidis or the seminiferous tubules. The sperm tail activity was maximal for cells within the vas deferens. PG synthetase activity was also observed in individual adipose cells adhering to the testicular capsule, epididymis and vas deferens, and in isolated interstitial cells of the testis and the caput, corpus and cauda epididymidis. Specific cells in the capsules of the testes, epididymis and vas deferens also produced PGs. The activity observed in the interstitial cells of the testis and the caput epididymidis was less than that for the other tissues in terms of the proportion of possible cells. The demonstration of PG synthetase activity paralleled to known loss of arachidonic acid from the phospholipids of the spermatozoa as they pass through the male tract. Endogenous substrate was not limiting in the assay system, even in the testis and caput epididymidis where PG synthesis was not normally observed, indicating that a PG synthesis inhibitor may be present in these two tissues. PG synthetase activity within teased seminiferous tubules was markedly increased by physical trauma. Indomethacin diminished but did not eliminate synthesis.