| HOME | HELP | FEEDBACK | SUBSCRIPTIONS | ARCHIVE | SEARCH | TABLE OF CONTENTS |
|
|
|
|||||||
|
|||||||||
Regular Article |
a Centre de Recherche en Biologie de la Reproduction et Département d'Obstétrique-Gynécologie, Faculté de Médecine, Université Laval, Ste-Foy, Quebec, Canada G1V 4G2
ABSTRACT
Sperm surface proteins involved in fertilization can be added or modified during epididymal transit. P34H, a human epididymal-sperm protein, appears on the sperm acrosomal cap in the distal caput-proximal corpus epididymis. In previous studies, it was shown that P34H is present on spermatozoa in men of proven fertility, is absent in 50% of men presenting with idiopathic infertility, and that a high proportion of men with normospermic vasovasectomy produce spermatozoa deficient in this sperm surface protein. P34H mRNA was expressed in the principal cells of the epididymis of normal men, predominantly in the corpus region. Recently, results coming from the assisted reproductive technologies have questioned the importance of the human epididymis in sperm maturation. In order to understand the effect of obstruction on the physiological state of the human epididymis and its function in sperm maturation, we have analyzed the expression of P34H mRNA at the level of the vas deferens and along the epididymis of normal and vasectomized men. In situ hybridization experiments showed that obstruction of the vas deferens alters the pattern of P34H mRNA expression compared with the tract of normal tissues. The P34H transcript was detected in the proximal caput epididymis of vasectomized men at a much higher intensity than that observed in the same region of normal tissues, being restricted to the principal cells of the epididymal epithelium. Compared with the normal duct, the lumen of vasectomized men was distended throughout the duct and the height of the epithelium was maximal in the caput. P34H mRNA was detectable in vas deferens, was not affected by vasectomy, and a 912-base pair P34H transcript was restricted to the epithelial cells of the vas deferens. Thus, using P34H as a marker, these results show that vasectomy alters the pattern of gene expression along the human epididymis, and suggest that the vas deferens can be a major contributor to sperm maturation in certain situations.
epididymis, fertilization, gene regulation, sperm, sperm maturation, vas deferens
INTRODUCTION
The mammalian epididymis is a single convoluted duct that conveys sperm from the testis to the vas deferens. The epididymis can be divided into three major regions: caput, corpus, and cauda. Caput and corpus epididymides are involved in the acquisition of sperm fertilizing ability, whereas the cauda segment is specialized in sperm storage [1, 2]. The three regions can be distinguished by their epithelial cell morphology [3] and by their specific patterns of gene expression [4]. The composition of luminal fluid, to which spermatozoa are exposed, depends on the epithelial cells lining the tubule that synthesize and secrete new proteins and certain blood compounds that are selectively transported into the epididymal lumen. Specific proteins present in luminal fluid are in many species acquired by epididymal spermatozoa [5] and play a function in the development of male gamete fertility. Some of these epididymal proteins interact with the sperm surface, either being incorporated to the plasma membrane or by modifying existing residues and thereby developing, or activating, sites involved in gamete recognition [6, 7]. Other proteins from the epididymal fluid act as decapacitating factors [8].
The human epididymis is also divided into three segments, however, the human cauda epididymis is less prominent than in other species, whereas the caput region has a rather bulbous form [9, 10]. The epididymal transit time for human sperm has been estimated to require 2–6 days [11] compared with 10–13 days in most other mammalian species [12]. The histology of its epithelium and the cellular changes that spermatozoa undergo suggest that sperm maturation in the lumen epididymis occurs essentially as it does in other mammals [9]. However, certain clinical results challenge the concept that exposure of human sperm to the epididymal microenvironment is necessary for sperm maturation and the development of a fertile ejaculate [13]. Fertility has been re-established in some men undergoing surgical anastomosis of the vas deferens to the epididymal duct, to the vasa efferentia, or even directly to a seminiferous tubule [14]. Furthermore, successful manipulations with testicular spermatozoa in terms of fertilizing ability [14, 15] seem to cast doubt on the theory of epididymal-dependent sperm maturation in humans.
Our laboratory has previously described a 34-kilodalton (kDa) human epididymal sperm protein (P34H) that is involved in the interaction of spermatozoa with the zona pellucida [16, 17]. P34H appears on human spermatozoa in the distal caput-proximal corpus epididymis and its location is restricted to the acrosomal cap [17]. Spermatozoa with low amounts of P34H exhibit dramatically decreased ability to interact with the zona pellucida [18], suggesting that this protein may be used as a marker of epididymal sperm maturation in men [19]. Moreover, a high proportion of normospermic vasovasectomized men produces spermatozoa that are deficient in this sperm surface protein [20]. We have shown that a 912-base pair (bp) P34H mRNA is expressed in the epididymis from normal men, predominantly in the corpus region. High levels of the P34H transcript are also found in the principal cells of the proximal and distal sections of the corpus epididymis [21].
The present investigation was undertaken to understand the effect of obstruction on the physiological function of the human excurrent duct and on subsequent sperm maturation in it, using vasectomized men as a model. The P34H mRNA expression in the vas deferens and along the epididymis of normal and vasectomized men was investigated using Northern blot analysis and in situ hybridization methodologies. The results are discussed with regard to the function of the human epididymis in sperm maturation.
MATERIALS AND METHODS
Tissue Preparation
Human epididymides were obtained through our local organ transplant program. The donors were 20–39 yr of age with no medical antecedent that could affect reproductive function except vasectomy. Tissues were collected while artificial circulation was maintained to preserve organs assigned for transplantation [17]. Due to geographical constraints, it was not possible to process epididymal tissues from vasectomized men in a time schedule that was compatible with mRNA extraction. Tissues were then fixed with paraformaldehyde (see below) to perform in situ hybridization.
Segments of the vasa deferentia were obtained from healthy patients of proven fertility who were undergoing vasectomy or vasovasostomy. The vasectomy was performed under local anesthesia by high bilateral incisions in the scrotum. Once the vas was identified, a short segment of it was removed. Ligation of both ends was performed with metallic clips after cauterization of the lumen. The vasovasostomy was performed under regional anesthesia by two scrotal incisions. The scarred portion of vas was removed. Small segments of both abdominal and testicular ends were excised. A modified one-layer anastomosis was performed under the microscope with interrupted 9–0 nylon sutures. Tissues from the vas deferens as well as from proximal and distal portions of caput, corpus, and cauda epididymides were fixed in freshly prepared 4% (w/v) paraformaldehyde in PBS, embedded in OCT medium (10.24% [w/w] polyvinyl alcohol, 4.26% [w/w] polyethylene glycol, 85.50% [w/w] nonreactive ingredients), and stored at -80°C until used for in situ hybridization. Vas deferens segments obtained during vasectomy and tissue fragments of corpus epididymis were rapidly frozen in liquid nitrogen for RNA extraction.
In Situ Hybridization of Tissue Sections
In situ hybridization was performed using digoxigenin (DIG)-labeled RNA probes as previously described [21]. Vas deferens and epididymis cryosections were fixed with freshly prepared 4% (w/v) paraformaldehyde in PBS for 5 min at room temperature, incubated for 10 min in 95% ethanol/5% acetic acid at -20°C, and rehydrated by successive baths of decreasing concentrations of ethanol diluted with diethylpyrocarbonate (DEPC)-treated H2O. Target RNA was unmasked by enzymatic digestion with 10 µg/ml proteinase K (Roche Diagnostics, Laval, Canada) in PBS for 10 min at 37°C, followed by a 5-min incubation in 0.2% glycine. Sections were postfixed for 5 min with 4% paraformaldehyde in PBS, acetylated with 0.25% acetic anhydride, 0.1 M triethanolamine pH 8.0 for 10 min, and finally washed with PBS.
Tissues were prehybridized for 1 h with 250 µg/ml salmon sperm DNA preheated in a hybridization solution (0.3 M NaCl, 0.01 M Tris-HCl pH 7.5, 1 mM EDTA, 1x Denhardts solution, 0.2% [w/v] Ficoll 400, 0.2% [w/v] polyvinylpyrrolidone, 0.2% [w/v] bovine serum albumin, 0.2 mg/ml herring sperm DNA [Sigma Chemicals, Mississauga, ON, Canada] 10% dextran sulfate, 0.1% SDS, 5% dextran sulfate, 0.02% SDS, and 50% formamide). Sections were then incubated overnight at 42°C under coverslips with 25 µl of 2 ng/ml heat-denaturated antisense or sense 900-bp cRNA [21] probed with DIG (Roche Diagnostics) according to the supplier's instructions. Sections were washed twice in 2x SSC at room temperature followed by two 10-min washes at 42°C in 2x SSC, 1x SSC, and 0.2x SSC.
Hybridization reactions were detected by immunostaining with alkaline phosphatase-conjugated DIG antibodies (Roche Diagnostics). Nonspecific staining was blocked by 1 h preincubation with 5% (v/v) heat-inactivated sheep serum in Tris-HCl/NaCl buffer (0.2 M Tris-HCl, 0.2 M NaCl, 3% triton X-100). Sections were then incubated for 2 h at room temperature with the alkaline phosphatase-conjugated anti-DIG antibodies diluted 1:1000 in blocking solution, washed with Tris-HCl/NaCl buffer, and incubated with 0.1 M Tris-HCl pH 9.5, 0.1 M NaCl, and 0.01 M MgCl2. The hybridization signal was visualized after a 10- to 15-min incubation period with the phosphatase substrate, nitroblue tetrazolium chloride, and 5-bromo-4-chloro-3-indolylphosphate p-toluidine salt (Gibco-BRL, Gaithersburg, MD). Levamisole (2 mM; Sigma) was added to the reaction mixture to inhibit endogenous alkaline phosphatase. Microscope slides were immersed in 1 mM EDTA, 0.01 Tris-HCl pH 7.5, washed for 5 min in H2O, counterstained with neutral red, dehydrated through baths of ethanol, cleared in xylene, and mounted with Permount (Fisher Scientific, Nepeau, ON, Canada). Epididymis sections were processed in parallel to allow comparison. Segments of vas deferens recovered following vasovasostomy procedure were processed separately.
Histological Examination
Seven-micrometer cryosections of the same epididymal segments used to perform in situ hybridization were stained with 0.75% hematoxylin and 1% eosin for light microscopic observation. Histomorphometric measurements were performed using a semiautomated image analyzer, the Bioquant True Color Windows 98 (R&M Biometrics Inc., Nashville, TN) and a SummaSketch III professional (Summagraphics, Anaheim, CA) digitalizing tablet in conjunction with a Leitz Aristoplan microscope (Leica, Canada) and Dage MTI black-and-white cooled camera. System calibration and quality control for accurate measurements were performed periodically with a calibrate scale bar, 20 µm spacing, and area and perimeter reference preparations (coefficient of variation [%] = 1.35).
The results are presented as means ± SEM. Statistical analysis was performed by ANOVA using super ANOVA software (Abacus Concepts, Berkeley, CA). Results were compared by Scheffe' test. Differences were considered to be significant at P < 0.01.
RNA Isolation and Northern Blot Analysis
Vas deferens segments from five to seven men undergoing vasectomy were pooled for total RNA extraction. Frozen tissue samples were homogenized in a guanidium thiocyanate solution (4 M guanidium thiocyanate, 25 mM sodium citrate pH 7, 0.5% sarcosyl, 0.1 M 2-ß-mercaptoethanol) followed by CsCl fractionation according to the method described by Chirgwin et al. [22]. The RNA pellets were resuspended in TES solution (10 mM Tris-HCl, 5 mM EDTA, 1% SDS pH 7.4), extracted once with phenol/chloroform (1:1) and twice with chloroform/alcohol isoamyl (24:1). RNAs were precipitated with 0.1 vol of sodium acetate (3 M pH 5.2) and 2.5 vol of 95% ethanol. The RNA pellets were resuspended in DEPC-treated water, quantitated by absorbence measurement at 260 nm, and stored at -80°C until used. All solutions were treated with DEPC.
Twenty micrograms of total RNA prepared from different tissues were denaturated in 50% formamide at 65°C for 15 min and separated by electrophoresis in 1% agarose gels containing 2.2 M formaldehyde [22]. RNA was transferred to nylon membranes (Qiagen, Santa Clarita, CA), ultraviolet cross-linked, and prehybridized at 42°C for 4 h in 50% (v/v) formamide, 0.75 M NaCl, 0.05 M NaH2PO4, 0.005 M EDTA, 2x Denhardts reagent, 0.2 mg/ml herring sperm DNA (Sigma Chemicals), 10% dextran sulfate, and 0.1% SDS. Hybridizations were performed in prehybridization solution supplemented with 1 x 106 cpm/ml of P34H cDNA or actin cDNA [21] at 42°C for 16 to 20 h. cDNA probes were random-prime-labeled using the T7 Quick-Prime kit (Pharmacia Biotech, Baie D'Urfé, PQ, Canada) with [
-32P]dCTP. Blots were subsequently washed twice at room temperature in 1x SSC, 0.1% SDS for 5 min, and twice at 65°C in 0.1x SSC for 30 min. Blots were exposed to X-Omat film (Kodak, Rochester, NY) at -80°C using intensifying screens for 16–18 h. An RNA ladder (1.6–7.4 kilobase, Gibco-BRL) was electrophoresed in parallel and an actin probe was used as a constitutive internal control.
RESULTS
Patterns of P34H mRNA Expression in the Epididymides of Vasectomized and Normal Men
Figure 1 illustrates typical results of in situ hybridization experiments performed on 10 and 5 biological specimens obtained from normal and vasectomized men, respectively. P34H transcript was detected in the proximal caput epididymides of vasectomized tissues at a much higher intensity than that observed in the same region of normal tissues (Fig. 1, A and B). The hybridization signal decreased throughout the subsequent segments of vasectomized tissues. When in situ hybridization was performed on epididymal tissues from normal men, the P34H transcript was predominantly expressed in the corpus segment, with highest intensity in the distal corpus epididymis (Fig. 1, E and G). The cauda sections from vasectomized and normal men revealed only weak hybridization signals (Fig. 1, I–L). In both normal and vasectomized men, P34H mRNA staining was restricted to the principal cells of the epididymal epithelium. No signal was detected when a sense strand of P34H cRNA was used as a negative control (Fig. 1, G*).
|
Effects of Vasectomy on the Histology of Human Epididymides
The histology of the epididymis was greatly affected by vasectomy (Fig. 1). In both normal and vasectomized epididymides, the lumen diameter increases from proximal caput to the distal cauda. In all segments, the diameter of the lumen was greatly enlarged following vasectomy (Figs. 1 and 2). As a consequence of vasectomy, the lumen surface of the cauda epididymis reached up to 1200 x 103 µm2 compared with 400 x 103 µm2 in normal men (Fig. 2A). In all the epididymal segments, the surface of the epididymal lumen of vasectomized men was significantly greater when compared with normal epididymis (P < 0.01).
|
In normal men, the epithelium height varied from one epididymal segment to the other, a maximum being reached in the distal caput-corpus epididymis. Following vasectomy, the maximum height of the epithelium was observed in the proximal caput epididymis, where it reached 70 µm. The height of the epithelium then decreased gradually to reach about 25 µm in the distal cauda (Fig. 2B). In normal men, the epithelium was higher in the distal caput compared with the proximal caput (P < 0.01), reaching a maximum in the corpus segment and then decreasing from the distal corpus to the distal cauda region. The epithelium in proximal caput epididymis of vasectomized men was similar to that characterizing the corpus epididymis of nonvasectomized men (Fig. 2B).
Localization of P34H Transcripts in Vas Deferens
Vas deferens segments recovered during vasectomy procedures were obtained with a delay compatible with mRNA extraction. P34H cDNA was used to probe the total RNA from human vas deferens and compared with the corpus epididymis (Fig. 3). Only the corpus segment of normal men was analyzed because it has been previously shown to be the segment with the highest level of P34H transcription [21]. In both the vas deferens and the corpus epididymis, the P34H transcript was detectable as a single band of 912 bp (Fig. 3A). The amount of P34H mRNA in vas deferens was approximately half of the signal intensity detected in the corpus epididymis (Fig. 3B).
|
The cellular location of P34H mRNA expression was determined by in situ hybridization on human ductus deferens obtained during vasectomy. Figure 4 shows a high level of P34H mRNA expression in the epithelial cells bordering the vas deferens lumen. The P34H mRNA staining was restricted to the principal cells of the human vas deferens (Fig. 4A). No signal was detectable when negative control hybridization was performed with a sense strand of P34H cRNA (Fig. 4B).
|
Effects of Vasectomy on the Expression of P34H mRNA in Human Vas Deferens
In order to evaluate the effect of vasectomy on P34H transcription in the vas deferens, in situ hybridization was performed on both testicular and abdominal segments removed during surgical vasectomy reversal. The vas deferens histology showed great differences when comparing one individual with another (Fig. 5, A and B vs. C and D) as well as when comparing the testicular (Fig. 5, A and C) with the abdominal segment (Fig. 5, B and D). In the six cases studied, five showed a swollen lumen on the testicular site and shrinkage on the abdominal site. Two representative results are presented in Figure 5. In the sixth case, the lumen of the vas deferens was similar in both testicular and abdominal, being crenellated with few infoldings (Fig. 5, A and B).
|
P34H transcripts could be detected in the epithelial cells in both abdominal and testicular sites of the vas deferens (Fig. 5). For each patient investigated, P34H mRNA levels were equivalent in both testicular and abdominal segments (Fig. 5). Quantities of tissues obtained during vasovasostomy were insufficient to compare by Northern blot the mRNA quantities in testicular versus abdominal vas deferens segments from each individual.
DISCUSSION
Even though direct evidence of epididymal sperm maturation in humans has never been documented by fertilization of zona pellucida-intact oocytes by spermatozoa collected at different levels of an intact epididymis, there is substantial indirect evidence to support this concept [23]. In the majority of mammalian species investigated, epididymal spermatozoa acquire the potential to fertilize when transiting the corpus and cauda epididymal regions [24, 25]. Based on andrological parameters regarding spermatozoa collected along the human epididymis [10, 23, 26] and on histological descriptions of the human excurrent duct [3, 12], there is no reason to believe that the function of the epididymis in humans is different from other mammalian species [9]. The majority of studies on sperm maturation in humans have been conducted using pathological tissues. Pathologies associated with epididymal obstructions are puzzling because in these situations, a small proportion of spermatozoa seem to acquire fertilizing potential in the more proximal region of the epididymis [27]. The physiological function of the epididymis thus appears to be modified following ductal obstruction. Elucidation of these modifications may clarify the status of the human epididymis with regard to sperm maturation and to understand the significance of clinical results obtained in pathological situations affecting the excurrent duct [28].
Very few proteins secreted in the lumen of the human epididymis have been shown to interact with the sperm surface and to be involved in sperm maturation [4, 29]. P34H is one of them [17]. We previously showed that P34H mRNA is predominantly expressed in proximal and distal sections of the corpus epididymis in normal men (Fig. 1) and [21]. Following vasectomy, P34H mRNA is predominantly located in the proximal region of the caput epididymis (Fig. 1). Following excurrent duct obstruction in men, other sperm surface changes have also been shown to occur at a much more proximal level than in patented excurrent ducts [23, 30]. Considering the potential function of these proteins, spermatozoa can acquire fertilizing potential in the more proximal region of the obstructed duct [27, 31].
Results from vas deferens anastomosis at different levels of the human epididymis suggest that exposure to a minimal proximal segment of the epididymis is beneficial for the acquisition of sperm fertilizing ability [30, 32, 33]. Some factors normally not expressed in the normal duct may be synthesized in a more proximal segment under obstructive situations, perhaps explaining in part the fact that human spermatozoa can mature in a very proximal region of obstructed human epididymis.
The consequences of vasectomy on epididymal histology have been described in different animal models and may not necessarily reflect the human situation [34, 35]. Compared with that of the normal unobstructed excurrent duct, the lumen is distended throughout most of the epididymis of vasectomized men and the epithelium is lower than that in the epididymis of normal men (Fig. 2). This could be a consequence of a high pressure along the obstructed duct, especially in the cauda, where sperm and fluid accumulate [36]. This phenomenon would be expected to alter the molecular and ionic environment in the epididymal lumen and could potentially alter epithelial synthesis and secretory activities [5]. We denoted an interesting relationship between the epithelium height and cellular location of P34H transcripts in normal and vasectomized men (Fig. 2). In both cases, P34H mRNA is expressed in the epididymal segments with the highest epithelium height: the distal corpus of normal epididymis and the proximal caput of vasectomized excurrent ducts (Figs. 1 and 2B). This could be associated with the fact that in the adult epididymis, protein synthesis is proportional to the height of the epithelium [12]. It thus appears that under the conditions imposed by vasectomy, the epithelium of the proximal caput dedifferentiates in a way that mimics the P34H synthetic patterns of the corpus segment. In a classic study by Bedford [37], spermatozoa were recovered at different parts of rabbit epididymis previously ligated in the low corpus region. The fertilizing potential of these spermatozoa was then evaluated at different periods of time postligation. From these results it was concluded that "As rabbit spermatozoa seem to need only about four days to pass from the vasa efferentia to the proximal part of the cauda, one might perhaps have expected to find fertile spermatozoa in the distal part of the caput rather sooner than eight and one-half to ten days after ligation in the low corpus region." This delay, which is necessary for spermatozoa to acquire fertilizing ability when sequestrated in the upper part of ligated epididymis, may well be explained by the time necessary for the upper portion of the excurrent duct to differentiate in accordance with the duct obstruction. In this unphysiological obstructive condition, the epididymis shows the versatility necessary to express, in its most proximal part, proteins necessary to sperm maturation that are normally synthesized in lower regions of unobstructed excurrent duct. The intraluminal, or "lumicrine" mechanisms [5, 38] modulating the expression of these factors remain to be defined. With regard to the histological consequences of vasectomy on the human epididymis (Figs. 1 and 2), it can be speculated that the intraluminal pressure in the proximal caput epididymis of vasectomized men is comparable to the one influencing the corpus epididymis of normal men. Thus, this intraluminal pressure could be a candidate for such modulation of the transcriptional activity of the epithelium along the excurrent duct. Another possibility is that vas deferens obstruction slows down the flux of testicular fluid entry in the epididymis as well as the spermatozoa transit within the epididymis, generating the establishment of new gradients of lumicrine factors. Consequently, this would lead to dedifferentiation of the epididymal epithelium because it is well-documented that the terminal differentiation of the epididymal epithelium is achieved by the combined effects of androgens and testicular factors. This way, proximal regions of the epididymis would acquire characteristics of normally more distal regions.
The surgical success of vasovasostomy in men is higher than the recovery of fertility [39–41]. This discrepancy could be associated with epididymal damage caused by vasectomy (Figs. 1 and 2). A high proportion of vasovasectomized men possess low levels of P34H on their spermatozoa and these levels have been hypothesized to be predictive of subfertility [19, 20]. This suggests that at least in some men, epididymal spermatozoa are not processed in a proper way to acquire P34H. Epididymal transit in humans has been estimated to require 2–6 days [11, 42] compared with 10–13 days in other mammalian species [12]. Therefore, sperm maturation in caput and corpus epididymides must occur very quickly in humans. It can be hypothesized that spermatozoa in some vasovasostomized men are not able to properly acquire P34H in the caput epididymis and that the epididymal maturation process is incomplete when the male gamete reaches the distal cauda of the obstructed excurrent duct.
A P34H transcript similar in length to the one expressed in the corpus epididymis [21] is present in human vas deferens (Fig. 3). Cellular location of P34H mRNA is restricted to the epithelium of the vas deferens (Fig. 4). The expression pattern of P34H is similar to the HE5 mRNA, showing maximum levels in the distal parts of the epididymis and in the vas deferens [8, 43, 44]. HE1, HE3, and HE4 transcripts have also been shown to be expressed in the vas deferens [4]. In humans, vas deferentia are well-developed and the epithelium bordering the lumen contains principal cells showing ultrastructural properties reflecting glycoprotein synthesis and secretion [45]. Thus, the human vas deferens may be more than a supportive conduit.
Vasovasostomy can be performed at different levels of the vas deferens. At the epididymal level, the lumen of the vas appears rather circular (Fig. 5, C and D), whereas it is more crenelated at a more distal (inguinal) level (Fig. 5, A and B). As a consequence of vasectomy in humans and animal models, the vas deferens lumen is enlarged at the testicular site of the ligation and is rather shrunken at the abdominal site (Fig. 5) [34, 35]. This effect is more pronounced when vasectomy is performed at a proximal level (Fig. 5, C and D vs. A and B). P34H mRNA is expressed on both testicular and abdominal sides after vasectomy (Fig. 5), suggesting that P34H expression in the vas deferens is not under the control of "lumicrine" factors [10, 38]. P34H transcription in the epididymis and vas deferens may thus depend on different regulatory mechanisms.
In conclusion, using P34H as a marker, our results show that vasectomy greatly affects the transcriptional activity of the excurrent duct. This change may have consequences on the recovery of fertility following surgical vasectomy reversal and may also help to explain clinical observations that have called into question previously accepted theories on the function of the epididymis in humans.
ACKNOWLEDGMENTS
We thank Dr. F. Boué for assistance in tissue preparation, Mr. V. Emond for statistical analysis, and Drs. J.M. Bedford and J.L. Bailey for critical reading of the manuscript.
FOOTNOTES
First decision: 16 August 2000.
1 This work was supported by a Medical Research Council-Canada grant to R.S.Correspondence: Robert Sullivan, Unité d'Ontogénie-Reproduction, Centre de Recherche, Centre Hospitalier de l'Université Laval, 2705 Blvd. Laurier, Ste-Foy, PQ, Canada G1V 4G2. FAX: 418 654 2765; robert.sullivan{at}crchul.ulaval.ca 
Accepted: October 5, 2000.
Received: July 25, 2000.
REFERENCES
This article has been cited by other articles:
|
|
 |
|
  G. A. Cornwall New insights into epididymal biology and function Hum. Reprod. Update, March 1, 2009; 15(2): 213 - 227. [Abstract] [Full Text] [PDF]
|
|
|
|
 |
|
 V. Thimon, G. Frenette, F. Saez, M. Thabet, and R. Sullivan Protein composition of human epididymosomes collected during surgical vasectomy reversal: a proteomic and genomic approach Hum. Reprod., August 1, 2008; 23(8): 1698 - 1707. [Abstract] [Full Text] [PDF]
|
|
|
|
 |
|
 V. Thimon, E. Calvo, O. Koukoui, C. Legare, and R. Sullivan Effects of Vasectomy on Gene Expression Profiling along the Human Epididymis Biol Reprod, August 1, 2008; 79(2): 262 - 273. [Abstract] [Full Text] [PDF]
|
|
|
|
 |
|
 C. Legare, M. Thabet, J.-L. Gatti, and R. Sullivan HE1/NPC2 status in human reproductive tract and ejaculated spermatozoa: consequence of vasectomy Mol. Hum. Reprod., July 1, 2006; 12(7): 461 - 468. [Abstract] [Full Text] [PDF]
|
|
|
|
 |
|
 F. Saez, C. Legare, J. Laflamme, and R. Sullivan Vasectomy-Dependent Dysregulation of a Local Renin-Angiotensin System in the Epididymis of the Cynomolgus Monkey (Macaca fascicularis) J Androl, September 1, 2004; 25(5): 784 - 796. [Abstract] [Full Text] [PDF]
|
|
|
|
|
|
C. Legare, N. Verville, and R. Sullivan Vasectomy Influences Expression of HE1 but not HE2 and HE5 Genes in Human Epididymis J Androl, January 1, 2004; 25(1): 30 - 43. [Abstract] [Full Text] [PDF]
|
|
|
|
|
|
K. Doiron, C. Legare, F. Saez, and R. Sullivan Effect of Vasectomy on Gene Expression in the Epididymis of Cynomolgus Monkey Biol Reprod, March 1, 2003; 68(3): 781 - 788. [Abstract] [Full Text] [PDF]
|
|
|
|
|
|
D. J. Cohen, D. A. Ellerman, D. Busso, M. M. Morgenfeld, A. D. Piazza, M. Hayashi, E. T. Young, M. Kasahara, and P. S. Cuasnicu Evidence That Human Epididymal Protein ARP Plays a Role in Gamete Fusion Through Complementary Sites on the Surface of the Human Egg Biol Reprod, October 1, 2001; 65(4): 1000 - 1005. [Abstract] [Full Text] [PDF]
|
|
| ||||||||||||||||||||||||||||||||||||||||||||||||||||||||||||||||||||||||||||||
| HOME | HELP | FEEDBACK | SUBSCRIPTIONS | ARCHIVE | SEARCH | TABLE OF CONTENTS |
