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This research aimed at revealing the structural features of Tibetan sheep's testicular and ovarian vasculature and providing theoretical basis for Tibetan sheep's physiological adaptability in plateau and low-oxygen environments. Through scanning electron microscopy, corrosion casts of the feature of the gonad arterioles were observed and analysed. The results of this study found that centrifugal arteries, centrifugal and centripetal arterioles were distributed in a 'dendritic' fashion in the testis lobule, the ovarian arteries and arterioles, which had a spiral shape. Testicular Tibetan Sheep knot-like artery had a denser spiral structure, and there were more branches in the microarteries. On the testis lobule and arteriole of caput epididymidis, the arteriole surface shows the 'fusiform' indentation to be more shallower. The ovarian artery had a higher degree of helix; its surface was distributed like a 'bark-like' indentation; and the ring was narrower and denser. Nevertheless, the arteriole network had a high concentration and a wide number of branches, as that of the ovarian arteriole network which had more end branches, the surface of the arterioles of ovaries and testicles was scarred and denser. The studies indicate that the structural features of testicular lobule, epididymal arterioles and ovarian arterioles are more conducive to increase the oxygen supply to the gonads tissue and controlling blood flow velocity and metabolism to respond to high altitudes and low-oxygen environments.

Scrotal sonography with a 7.5 MHz sector scanner was performed on 658 consecutive patients of our infertility clinic. The incidence of pathological findings was unexpectedly high. Forty per cent of the patients revealed pathological structures such as varicoceles (21%), hydroceles (7%), epididymal abnormalities (6%), spermatoceles (6%), intratesticular hyper- and hypoechoic changes (4.5%), intratesticular cysts (1%) and tumours or carcinoma in situ (CIS) (0.6%). Sonographic evaluation and measurement of the caput epididymidis was compared with palpation. Sonography distinguished size ranges of "normal" and "thickened" epididymides as diagnosed by palpation. Cystic structures were proven in 56% of cases with "thickened" epididymides. The sonographically determined diameters of doppler-negative blood vessels were significantly smaller than those of doppler-positive vessels. Sonography revealed a higher occurrence of varicoceles than diagnosed by palpation (76% by palpation). Only 58% of sonographically identified hydroceles and only 67% of sonographically detected spermatoceles were detected by palpation. One testicular tumour and one case with CIS were only seen by sonography and not suspected on palpation. The results demonstrate that sonography represents a valuable tool in the routine diagnosis of andrological patients.

Epididymal sperm reserve was determined in 6 sexually mature fertile buffalo-bulls having normal process of spermatogenesis. The relative distribution of spermatozoa in the caput, corpus and cauda epididymidis averaged 5.42, 0.75 and 11.45 billion respectively. Total epididymal sperm reserve per bull averaged 36.2 billion. In terms of percentage the caput, corpus and cauda epididymidis contained 30.76, 4.25 and 64.99 per cent sperm respectively.

This study was designed to explore the different expression of L-PGDS (lipocalin-type prostaglandin D synthase) in rat epididymidis and to gain further insight into the potential function of L-PGDS in male reproduction. The expression of L-PGDS in rat epididymidis was assessed using real-time quantitative PCR and immunoblotting. The distribution of L-PGDS in rat epididymidis was explored by immunohistochemical methods. The result of immunohistochemistry displayed that L-PGDS was mainly distributed in epididymidis and localized within the cytoplasm and the cilia of the epithelial cells. Real-time quantitative PCR and immunoblotting showed that L-PGDS was strikingly expressed in the caput epididymidis, while a moderate to weak expression was observed in the corpus and cauda epididymidis, the level of mRNA was 0.52 ± 0.02 in the caput, 0.48 ± 0.03 in the corpus and 0.32 ± 0.01 in the cauda epididymidis, the level of protein expression in caput, corpus and the cauda groups was 1, 0.89 ± 0.03 and 0.62 ± 0.01, which suggested that L-PGDS may play certain kind of role during the process of the spermatozoa maturation.

Phospholipids and sterols are known to have multiple functions in reproductive tissue of mammals. High concentrations of the cholesterol precursor desmosterol have been described in testis, epididymis, and spermatozoa of various species. These findings and the recent discovery of some cholesterol precursors as meiosis-activating sterols suggest important functions of cholesterol precursors in fertility. Many sterol intermediates appear from the 19-step conversion of lanosterol, the first sterol synthesized in the cascade of cholesterol synthesis, to cholesterol. The bio- chemical basis of the genetically inherited Smith-Lemli- Opitz syndrome has been described as a defective conver- sion of 7-dehydrocholesterol to cholesterol. Since this dis- covery, interest has focused on this special cholesterol pre- cursor. Here, we report high concentrations of 7- and 8-dehydrocholesterol in caput epididymidis and spermato- zoa derived from caput epididymidis of Sprague-Dawley and Wistar rats, which comprised up to 30% of total sterols. In contrast to caput epididymidis, 7- and 8-dehydrocholes- terol were barely detected in cauda epididymidis or testis. Desmosterol increased several times from caput to cauda epididymidis. This is the first report of the natural ap- pearance of high concentrations of dehydrocholesterols in mammalian tissue, and it underlines the putative impor- tance of cholesterol precursors in reproductive tissue. — Lindenthal, B., T. A. Aldaghlas, J. K. Kelleher, S. M. Henkel, R. Tolba, G. Haidl, and K. von Bergmann. Neutral sterols of rat epididymis: high concentrations of dehydrocholesterols in rat caput epididymidis. J. Lipid Res. 2001. 42: 1089-1095.

The objectives of the present study are to characterize the motility and penetrability into zona-free hamster eggs of boar spermatozoa from 7 regions of the epididymis. Spermatozoa from the caput epididymidis were immotile or exhibited a flagellant or circular type of movement. However, 80% of the cells from the proximal cauda showed an intensive, forward movement. When the spermatozoa from each region of the epididymis were coincubated with zona-free hamster eggs after preincubation for inducing the acrosome reaction, they exhibited high penetration rates (95-100%) and average number of spermatozoa (3.4-5.8) in penetrated eggs irrespective of their origin. These findings indicate that most of the spermatozoa acquire the ability to exhibit progressive motility during their transit through the corpus, and that at least some of the cells located in the proximal caput have the ability to fuse with egg plasma membrane.

Epididymal cysts are the commonest intrascrotal cystic swellings and are invariably benign. The incidence increases with age and the commonest site is the caput epididymidis. The vast majority are asymptomatic and indications for surgery are uncommon but can include pain or cosmesis. Surgical extirpation of these cysts risks epididymal obstruction and should not be taken lightly in patients who may want to father children.Recurrence following cyst excision is very common due to the nature of the epididymis. Excision of the whole epididymal gland prevents this but with the consequence of causing irreversible unilateral testicular obstruction.

Endothelin-1 (ET-1) is a potent vasoconstrictor localized for the first time in porcine aortic endothelial cells (Yanagisawa et al., 1988). Endothelin receptors can be classified as subtype A (ET-A) and subtype B (ET-B). The aim of this study was to examine the expression of ET-1 and its receptors in the human epididymis. Morphologically, the human epididymis is commonly divided into three major parts: caput, corpus and cauda epididymidis (Holstein, 1969). The caput epididymidis contains mainly parts of efferent ducts (Yeung et al., 1991) while the corpus and cauda epididymidis comprise epididymal duct.

We report a rare case of systemic sarcoidosis involving the epididymis. An irregularly shaped heterogeneous lesion was identified with ultrasonography in the left caput epididymidis. Microscopically, a number of noncaseating epi-thelioid cell granulomas were found in the epididymal tissue.

Drastic measures are required to curtail the ever burgeoning world population. Fortunately, the male partner is becoming more aware of family planning (WHO 1980) and the problem seems to be less one of a willingness to contribute than a lack of a suitable method (but see Nieschlag, this volume). As an alternative to the testicular approach, the epididymis has often been mooted as an attractive site for attack by a contraceptive designed for use by men (Hinton 1980; Ford and Waites 1986) for three main reasons: (a) the onset of infertility (and rapid return to fertility after withdrawal of treatment) should be far quicker than any agent attacking the testicular production of spermatozoa; (b) damage to the genetic material, a possible sequela of action on dividing germ cells, may be obviated when attack is on maturing cells and (c) the natural function of the epididymis (that of mixing its secretions with spermatozoa) would be exploited. Concerning point (a), there may not be much difference in onset of action between an agent acting on spermiation or acting at the level of the caput epididymidis. Considering point (b), recent evidence has shown that administration of cyclophosphamide can cause embryonic malformation when given to male rats in which the ligated efferent ducts prevent spermatozoa from being attacked by the drug in the testis (Robaire, personal communication). The prime advantage of an epididymal approach, therefore, would be that the drug of choice would be delivered to, and thorough mixed with, spermatozoa, thus preventing the normal sperm-secretion interactions or creating a hostile environment for spermatozoa.

Development of the testis, epididymis and prostate in 53 male beagles was examined histologically with PAS-hematoxylin stain from birth to sexual maturity. The diameter of the seminiferous tubules of the testes was less than 100 microns until 20 weeks of age, however, it increased markedly between 22 and 28 week of age, reaching 180 +/- 7 (mean +/- SD) microns at 28 weeks of age. Only Sertoli cells and gonocytes (or spermatogonia) were detected in the seminiferous tubules until 16 weeks of age. Spermatocytes and spermatids appeared in the tubules at 20 and 22 weeks of age, respectively. Spermatozoa were first observed in the testes of 2 of the 5 dogs at 26 weeks of age and were found in the testes of all the 3 dogs at 28 weeks of age. The diameter of the ducts in the cauda epididymidis was 146 +/- 4 microns at 20 weeks of age. Thereafter it increased markedly, reaching 341 +/- 14 microns at 28 weeks of age. The height of the epithelium and stereocilia in the ducts of the caput epididymidis increased markedly at about 28 weeks of age. A large number of spermatozoa was seen in the lumens of the ducts of the corpus and cauda epididymidis after 32 weeks of age. The shape of the lumens in the glandular alveoli of the prostate became irregular as a result of projection of the glandular epithelium into the enlarged lumens and the epithelial cells of the alveoli became PAS-positive at 24 weeks of age.(ABSTRACT TRUNCATED AT 250 WORDS)

Microvasculature of the epididymis was investigated by scanning electron microscopy of vascular corrosion casts. The basic structure of blood supply to the boar epididymis consists of two superimposed vascular networks. Capillaries surrounding the epididymal duct constitute the inner level. They form polygonal meshes around the efferent ductules whereas circular capillaries strongly predominate in the subsequent region of the caput epididymidis. This annulate feature is progressively lost from corpus to cauda, where the capillary network once again has a polygonal appearance. The outer network is composed of feeding and draining vessels. Intertubular arteries pass between the loops of the epididymal duct and give rise to longitudinally oriented vessels attributable to only one adjacent duct segment. They feed the capillary network via circular ramifications debouching in different sectors of its circumference. The sparse veins draining the capillaries encircling the efferent ductules give way to a gradually increasing number of confluent veins up to the cauda.

The effects of a single subcutaneous injection of CdQ2 (0.04 mmol/kg body weight) were studied on the testes and caput epididymidis of a non-scrotal mammal, Hemiechinus auritus, and scrotal laboratory mouse. The histological structure of the testes and caput epididymidis of the hedgehog remains normal after 21 days of CdCl2 injection. Testes and sex accessory glands did not show any significant change in weight. The testes and sex accessory organs of mice under comparable condition showed weight loss and involution in tubule diameter. A temperature differential of 1°C was found to exist between the rectum and the cremaster sac of the hedgehog. This small temperature difference and the absence of a counter-current mechanism may be involved in conferring the CdCl2 resistance to the testes and epididymis of the hedgehog.

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.

A technique is described for the rapid isolation of principal cells from enzymatically dispersed rat caput epididymidis by differential sedimentation into calf serum. Sedimentations were prepared in common glass separatory funnels. Sperm-free, principal cell populations that were 66.6% pure and averaged 106 cells were isolated after 10 minutes of sedimentation. This represents a twofold enrichment in principal cells over that achieved in the dispersed tissue suspension. Based on dye exclusion tests, viability of principal cells after separation was 90% suggesting that the cells are well suited for physiologic study.

We have been able to culture caput epididymal tubules from rats by modifying an organ culture system (Orgebin-Crist et al, 1980) which was used to culture rabbit corpus epididymal tubule segments. The morphology of the epithelium was consistently good throughout seven days in culture, although sloughed epithelium was commonly seen during the first 24 hours. Evidence of this sloughing was much less frequent thereafter. Throughout seven days of culture, autoradiography of SDS-PAGE of luminal fluid obtained from tubules cultured in medium containing 14C-L-leucine showed incorporation into bands identical to those stained by Coomassie Blue. Rat epididymal alpha-lactalbumin was consistently localized on the luminal surface of the epithelium and the middle piece of the spermatozoa. Spermatozoa appeared to have normal morphology throughout the first three days in culture; thereafter, decapitated spermatozoa were frequently seen. Caput spermatozoa only quiver in place prior to culture, but after three days in culture, 53% of the spermatozoa from distal caput tubules are progressively motile upon dilution in a balanced salt solution. Since the transit time for spermatozoa in the caput epididymidis of the rat is approximately three days, it should be possible with this culture system to study maturational events involving interactions between spermatozoa and the epididymal epithelium.

Micropuncture techniques developed for the study of renal physiology have been adapted for investigation of the male reproductive tract. Ultramicro specimens were obtained in vivo from the tubules of the rat testis and epididymis. These samples were analyzed for sperm morphology and concentration. The new methods developed to conduct these studies are discussed in detail. The mean in vivo spermatocrits were 0.411 plus and minus 0.029, 0.355 plus and minus 0.019, and 0;731 plus and minus 0.028 in the seminiferous tubule, caput epididymidis, and caudal spermatocrit was significantly higher than the spermatocrit in the caput or seminiferous tubule. The percentages of abnormal spermatozoa in the caput and cauda were 5.5% plus and minus .7% and 4.3% plus and minus .6%, respectively.

Scrotal insulation for 48 h raised subcutaneous scrotal temperature by 4 degrees C in hybrid Bos indicus X Bos taurus bulls. The incidence of decapitated spermatozoa in the ejaculate increased significantly between 6 and 14 days and that of protoplasmic droplets and tail abnormalities between 20 and 23 days after insulation, respectively. Simultaneously, the percentages of spermatozoa with lost and damaged acrosomes increased significantly 12-17 days after insulation. At slaughter 23 days after scrotal insulation sperm production rates and gonadal reserves had not been affected by insulation, but epididymal reserves were markedly reduced, particularly in the cauda. Elevated testicular temperature therefore had an effect on immature spermatozoa in the caput epididymidis and on spermatids, but it is suggested that selective sperm resorption in the rete testis and excurrent ducts may prevent some of these changes being expressed in the ejaculate.

Summary. The specific activity of the type I and type II isoenzyme forms of the cAMP-dependent protein kinase (EC 2.7.1.37) in the caput epididymidis of the intact rat was less than that of the caudal region while the isoenzyme ratio (type II :type I) of the former was greater than that of the latter, with type II being the predominant form in both regions. By 7 days after castration, the specific activities in both regions had decreased to the same level. The isoenzyme ratio of the caudal region increased to that of the caput region which remained unchanged after castration. The change in the isoenzyme ratio in the caudal region was mainly due to loss of the type I isoenzyme. The castration effects were reversed by testosterone administration.

In order to obtain the information on the morphological changes occuring in sperm at various regions along the epididymis, forty one boars of Randrace breed were used for the examination of the morphology of sperm in epididymal content from four regions of epididymis. Samples were collected post mortem from the proxi-mal and distal parts of caput and cauda epididymides, respectively.The results obtained are as follows:There was a highly significant decrease in the incidence of abnormal sperm heads (pear-shaped, narrow at the base and narrow) during the passage from the proximal to the distal region of caput epididymidis. The decrease in the incidence of abnormal head with these types may be due to selective resorption or dissolution of sperm in the epithelium of caput epididymidis. Migration of cytoplasmic droplet from the prox-imal to distal position of middle-piece increased progressively during the passage of sperm through the epididymis, and largest migration took place from the proximal to distal region of caput epididymidis. While the incidence of bent tail sperm increased during the passage along the epididymis, it reached maximum in the proximal region of cauda epididymidis. These finding suggest that ability of selective sperm resorption in epididymal epithelium of caput is very active, and it contribute to the improvement semen picture after ejaculation. Studies on morphological characteristics of ejaculated sperm would be important for evaluation of the function at different regions of epididymis.

Experiments were performed to further the understanding of epididymal processes involved in the acquisition of sperm motility. Samples of luminal contents were collected by micropuncture from four regions of the rat epididymis. These samples were incubated in various diluents to observe the effects of the diluents on sperm motility. Consonant with previous reports, 40 mM glycerylphosphorylcholine (GPC) and 60 mM DL-carnitine reduced overall motility scores of cauda epididymidal spermatozoa but did not prevent normal initiation of motility. Additionally, control sperm cells and cells treated with carnitine could reinitiate full motility after becoming immotile. Spermatozoa treated with GPC could not reinitiate motility. The sperm cells in our system thus react to GPC and carnitine in fundamentally different ways, the exact nature of which remains to be determined. Spermatozoa from the distal caput epididymidis evidenced high motility scores when diluted in a 5% egg yolk + 10 mM caffeine diluent. It was demonstrated, however, that the subjective appearance of full motility in these immature cells was not supported by actual progressive motility as measured in an assay of linear distance traveled. It was concluded that neither 10 mM caffeine, 5% egg yolk, nor their combination was sufficient to induce progressive motility in immature rat spermatozoa.

Gossypol acetic acid was administered orally to mice of two inbred strains, BALB/c/O1a and CBA/Gr, at daily doses of 10 or 20 mg/kg for about 4 weeks. Treated mice of both strains showed a reduction in sperm counts. This was more marked in CBA mice, which also had smaller testes size than did BALB/c mice. The treatment had no significant effect on testicular weight but the caput epididymidis and seminal vesicles of treated mice weighed less than those of control mice.

Studies of epididymal function would be facilitated if principal or basal cells could be cultured. Principal cells from the caput epididymidis were isolated by elutriation and suspended (4 X 106 /ml) in culture medium supplemented with serum. Cells were cultured at 34#{176}C within a floatingcollagen matrix prepared by mixing equal volumes of the principalcellsuspension and an ice-cold collagen solution when plating the cells in the culture dish. After 20-24 h, serum-free medium was used. Cultures contained both isolated cells and clusters of cells surrounded by collagen fibers, but cell division was not seen. Based on observations by transmission electron microscopy, 82% of the cells in Day 5 cultures were principal cells and 75% of these cells were morphologically normal. Fine structure of principal cells on Days 1, 3 or 5 was similar to that of cells in situ. Metabolism of �3 HI testosterone was evaluated over Days 1-3 and 3-5. Virtually all

Tissue pieces from the caput epididymidis of the rat were incubated in vitro with (35S) methionine to produce radioactive secretory proteins. The radioactive secretory proteins so formed were tested for their ability to bind to washed rat spermatozoa collected from the rete testis and cauda epididymidis, and to rat erythrocytes. The sperm and erythrocytes bound approximately 5% of the total radioactive protein. Binding was protein-specific in that only selected proteins became associated with the cells. Binding was not cell-specific, however, since testicular spermatozoa, caudal spermatozoa, and erythrocytes all bound the same proteins to a similar degree.

Spermatozoa from the testis and various regions along the epididymis of the rat were collected by micropuncture and their motility after dilution was estimated over a 15-min period by using a Quantimet image analyser. The motility of sermatozoa from the rete testis and seminiferous tubules was too low to be measured. The estimate of motility of spermatozoa from the proximal caput epididymidis was much lower than that of spermatozoa from the other regions. Spermatozoa from the distal part of the caput showed sustained motility for 15 min, whereas those from the caudal region and ductus deferens, although active initially, became less active during this period.

Intra-testicular temperatures of conscious boars were in the range 35.0-36.5 degrees C; values for the caput epididymidis were 35.5-37.0 degrees C and for the cauda epididymidis 35.3-37.0 degrees C. The modal temperatures of these tissues were approximately 2.5, 1.5 and 1.9 degrees C respectively below rectal temperature (38.2 degrees C) and each tissue temperature varied diurnally. With increasing environmental temperature (from 23 to 34 degrees c), testicular and epididymal temperatures increased, and the differential between tissue and rectal temperature levels diminished. The temperature of the caput epididymidis changed most with rising environmental temperature. It is possible to predict testis or epididymal temperature from environmental or rectal temperature.

An examination of the site of origin of the 17β-hydroxy-5α-androstan-3-one (5αDHT) binding protein that exists in cytosol prepared from the caput epididymidis from sexually-mature intact rabbits was approached in the following way: Rabbits a) had the ductuli efferent es unilaterally ligated, b) were hemicastrated, c) were made unilaterally cryptorchid. These procedures were designed to decrease or eliminate the flow of testicular fluid into the epididymis. When this occurred, there was a marked decrease or total elimination of 5αDHT binding to cytosol prepared from the caput from the experimental epididymis, as compared to cytosol from the contralateral control side. These results suggest that the 5αDHT binding moiety in cytosol prepared from the caput epididymidis from intact sexually-mature rabbits is of testicular origin and is not the target tissue “receptor.”

The secretory activity of the middle segment of the mouse caput epididymidis was studied using 3H-fucose as a precursor to glycoprotein. Young adult male mice were injected with a concentrated solution of 3H-fucose interstitially, ie beneath the connective tissue capsule of the epididymis. Two animals were killed and prepared for light microscopic radioautography at each of six intervals between 10 minutes and 24 hours after injection. Silver grains were concentrated over the supranuclear Golgi region at 10 minutes and over the apical ends of the cells 30 minutes and 1 hour after injection. Quantitative analysis showed that luminal radioactivity increased greatly beginning with the 2-hour samples. The results indicate that the epididymal epithelium synthesizes and secretes glycoproteins, and that 1 to 2 hours are required for terminal glycosylation, intracellular transport, and release of the secretory product.

The highest levels of carnitine and acetylcarnitine were found in the cauda, and spermatozoa from the proximal cauda contained significantly greater amounts of carnitine than those removed from the corpus or caput epididymidis. Acetylcarnitine levels (as a % of the total carnitine pool) were greater in all regions of the rabbit epididymis than has been reported in other species. It is suggested that the accumulation of carnitine is involved in sperm maturation.

The fluid transporting spermatozoa out of the testis through the epididymis is known to undergo many changes. About 50% of the fluid secreted by the seminiferous tubules is reabsorbed by the first part of the epididymal duct system (Crabo & Gustafsson, 1964; Levine & Marsh, 1971). Between the caput epididymidis and the ductus deferens, a further 50% of the remaining fluid is reabsorbed. Seminiferous tubule fluid and rete testis fluid contain several protein fractions not seen in the serum, as has been shown by polyacrylamide gel electrophoresis (Kormano, Koskimies & Hunter, 1971; Koskimies & Kormano, 1973). The fate and significance of most of these proteins is unknown. Recently, it has been shown electrophoretically that bovine epididymal plasma from the cauda region contains at least three proteins not detected in the rete testis fluid

Sixteen rabbits were injected with thymidine-3H and tissue sections or spermatozoa smears were evaluated by autoradiography. Two successive ejaculates were collected every second day. Analyses of labelled germ cells in twenty-four testes taken 1 hr to 32 days postinjection showed that one cycle of the seminiferous epithelium required 10\m=.\7 \m=+-\0\m=.\5days and that labelled spermatozoa should enter the caput epididymidis 31\m=.\4days post-injection. Labelled spermatozoa were found in the proximal portion of four capita epididymidum 32 days and one caput 33 days post-injection, but not in eleven other capita epididymidum 28 to 31 days post-injection. Labelled spermatozoa first were detected in ejaculated semen from five rabbits on Days 38, 39, 41, 42 and 42. The mean number of grains/spermatozoon in autoradiograms of successive samples agreed closely with the scintillation count activity

When spermatozoa from specific segments of the epididymis were inseminated intra-tubally, ten hours before ovulation, virtually no ova were fertilized by sperm samples taken from the regions proximal to the middle of the corpus epididymidis. Sperm from the caput epididymidis and the proximal half of the corpus region not only fail to fertilize, but are also apparently unable to establish contact with the surface of the zona pellucida. Although a maximal fertilization rate was obtained with sperm samples from the lower part of the corpus epididymidis, significantly greater numbers of supplementary and zona surface spermatozoa were found in association with tubal ova exposed to similar numbers of sperm from the cauda epididymidis. This latter finding suggests that the cauda region contains a relatively higher percentage of mature spermatozoa, and thus that a proportion of spermatozoa do not become functionally mature until they have passed from the corpus epididymidis. Approximately 7% and 5% of ova exposed to spermatozoa from the lower corpus and cauda regions, respectively, contained three and occasionally four pronuclei, quite probably as a consequence of polyspermic fertilization. As no polyploid ova were found after similar exposure to greater numbers of ejaculated spermatozoa (Adams and Chang, '62), it is conceivable that there may be other systems on the sperm head, as well as those concerned with penetration of the zona, which also mature in some way during epididymal passage.

Ligatures were placed unilaterally on the ductus deferens (experiment 1), on the ductus deferens and the middle of the corpus epididymidis (experiment 2) and on the ductus deferens, corpus epididymidis and ductuli efferentes (experiment 3) in 39 rabbits. The untreated contralateral side served as a control. Vasectomy alone appeared to have no effect upon the testes, or upon spermatozoa accumulated during a period of 12 weeks proximal to the ligature. In experiment 2 severe disruption of spermatogenesis occurred. Diameter of the seminiferous tubules decreased, testes atrophied, and the stages of the seminiferous epithelium were abnormal and often not classifiable. Some regeneration was observed after 12 weeks. In experiment 3 there was only a moderate and more transient disturbance of spermatogenesis. This occurred in spite of an accumulation of fluid in the testis due to the ligature on the ductuli efferentes, which prevented testicular effluent from reaching the caput epididymidis. These results suggest that when testicular effluent is allowed to reach the caput, but nonresorbed residues are prevented from further transport (experiment 2), a feedback to the testis occurs which is more harmful than that produced by preventing tubular contents from leaving the testes.

The distribution of adrenergic nerves to the male reproductive ducts were studied by applying the highly specific method of Falck and Hillarp for the cellular demonstration of the adrenergic transmitter. In rats, guinea-pigs, and rabbits, the ducts of the testis and the caput epididymidis were found to lack adrenergic varicose terminals, as they also lack cholinesterase positive structures. Adrenergic terminals extend in the vas deferens and epididymis from the prostatic end as far as the upper mid-corpus level of the ductus epididymidis, occurring in the muscle layers and, except in the rat, in the lamina propria. In the cat, ductuli efferentes and caput epididymidis also receive an adrenergic innervation.

SUMMARY The content and concentration of sialic acid in the testis, caput epididy-midis, cauda epididymidis and ductus deferens show changes during the transition from the prepuberal to the puberal (mature) state in the rat. The peak of sialic acid is attained in the caput epididymidis and cauda epididy-midis and ductus deferens between days 40 and 45 prior to the entry of sperms into these regions. Following the entry of sperms there is a sharp decline in sialic acid till day 60 in the caput epididymidis and ductus deferens while in the cauda epididymidis the decline in sialic acid is only transient between days 45 and 50 and is followed by sharp increase at day 60. Efferent duct ligation caused a marked decrease in content of sialic acid in the caput epididymidis only. The significance of these changes is discussed in relation to the maturation of spermatozoa.

1. 1. Seven major lipids of rat spermatozoa from the caput, corpus and cauda epididymidis were separated and quantitated by TLC. 2. 2. Spermatozoa from the caput epididymidis had a significantly greater (P < 0.05) content of phospholipid, cholesterol, cholesterol ester and free fatty acid than those from the cauda epididymidis. 3. 3. Spermatozoa from the corpus epidiymidis had a significantly greater (P < 0.05) content of monoglyceride than those from the caput epididymidis and a greater content of phospholipid, cholesterol, free fatty acids and monoglyceride than those from the cauda epididymidis.

1. 1. The in vivo uptake and metabolism of 65Zn over, 1, 3, 6, 24 and 48 hr by rat spermatozoa from the caput, corpus and cauda epididymidis were determined. 2. 2. The differences in 65Zn content of spermatozoa from the caput epididymidis at 3 hr vs. the content at 24 and 48 hr approached significance (P 3. 3. The 65Zn level of spermatozoa from the corpus epididymidis at 1 and 3 hr differed significantly (P 4. 4. There were no significant (P

The absorption of L-carnitine from the duct of the proximal regions of the rat epididymis was investigated using a stopped-flow, split-droplet microperfusion technique. L-carnitine was absorbed from the duct of the proximal caput epididymidis by a time-dependent and saturable transport system (Km = 25 micron; Vmax = 0.65 pmoles absorbed/min/mm3 tubular volume). Furthermore, absorption appeared to be primarily sodium-independent, although the existence of a minor sodium-dependent pathway cannot be ruled out. A similar transport system was not evident along the distal caput epididymidis, where absorption of L-carnitine was attributable to passive diffusion only. The inward and outward movement of L-carnitine across the epithelium of the proximal and distal caput epididymidis appears to be regulated so that the spermatozoa come into contact with high levels of L-carnitine in the distal caput region.

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.

Smooth muscle electrical activity was recorded with suction electrodes from the partly or completely uncoiled epididymal duct of the rat in vitro. The electrical activity of the cauda epididymidis consisted of one or few spikes followed by a plateau of 1-2 sec. The frequency of electrical activity declined from the thicker-walled initial segment of the thin-walled initial segment, was increased to the level seen in the initial segment in the thicker, major portion of the caput epididymidis, declined in the corpus and fell steeply in the cauda epididymidis towards the vas deferens. Electrical activity spread over long distances in the distal cauda and epididymal vas. Elsewhere in the epididymis activity remained synchronous only for a short period in short segments.