Apparent fertility of human spermatozoa from the caput epididymidis

Fifty-one patients with obstructive azoospermia caused by blockage at the caput epididymidis have been followed for 4 years after undergoing "specific tubule" vasoepididymostomy, bypassing the corpus and cauda. The patency rate was 73%, and the pregnancy rate was 31%. There was no correlation between sperm count and pregnancy rate, but there was a strong correlation with sperm motility. With less than 20% motility, only 15% of the patients became pregnant, but with greater than 20% motility postoperatively, 58% became pregnant. If the wife was over 30 years old, only 21% got pregnant. If the wife was under 30, 67% got pregnant. "Redo" cases were just as likely to succeed as "first-time" attempts. In the "patent" cases, 43% of patients with spermatozoa that never reached or traversed the corpus or cauda epididymidis produced a pregnancy. Spermatozoa from the proximal caput produced a 33% pregnancy rate, whereas spermatozoa from the distal caput produced a 50% pregnancy rate. One-half of the pregnancies occurred more than 2 years postoperatively.     

Clinical observation of loupe-assisted intussusception vasoepididymostomy in the treatment of obstructive azoospermia (analysis of 49 case reports)

To evaluate the clinical outcomes of loupe-assisted intussusception vasoepididymostomy (VE) in the treatment of epididymal obstructive azoospermia (EOA), we retrospectively analyzed data from 49 patients with EOA who underwent two-suture longitudinal intussusception vasoepididymostomy (LIVE) between 2000 and 2007. The data included the surgical method, postoperative motile sperm count per ejaculation, percentage of progressive motile sperm and patency and pregnancy outcomes. There were a total of 49 men undergoing scrotal exploration, and epididymal obstruction was found in all cases. Bilateral or unilateral anastomoses were performed in 40 and 6 men, respectively. The postoperative courses of 42 patients were followed up for more than 6 months, and the courses of 38 patients were followed up for more than 1 year. The overall patency and pregnancy rates were 71.4% and 26.3%, respectively. Moreover, progressive motile sperm was more frequently present in those patients who had undergone anastomosis at cauda than at corpus or caput. Pregnancy was achieved only in those patients who had undergone anastomosis at least on one side of the cauda epididymis. We think that the loupe-assisted method, with a lower overall cost and a simplified surgical procedure, can achieve satisfactory patency outcomes and pregnancy results. Data from this paper also suggest that paternity outcomes occur more frequently after anastomoses at cauda than at corpus or caput.     

FERTILITY OUTCOME AFTER REPEAT VASOEPIDIDYMOSTOMY

PURPOSE: Historically, epididymal obstruction has been treated with surgical reconstruction. We determine whether it is worthwhile for patients to undergo repeat surgical reconstruction after failed vasoepididymostomy or whether they should be advised only to undergo sperm acquisition for assisted reproductive technique. MATERIALS AND METHODS: A total of 18 patients underwent repeat vasoepididymostomy performed by a single urologist (A. J. T.). Cases were divided based on the etiology of obstruction into groups 1--prior vasectomy (4), 2--congenital (7) and 3--inflammatory (7). Data were available regarding time of obstruction between initial and repeat vasoepididymostomy, quality of epididymal fluid, levels of anastomoses, semen analyses at least 12 months after surgery for all 18 men and pregnancy rates based on more than 18 months of followup in 12. RESULTS: Mean patient age at repeat vasoepididymostomy was 40.6 years (50.5, 36 and 39.4 years for groups 1, 2 and 3, respectively). Mean interval between vasectomy and initial vasoepididymostomy was 12.3 years (range 10 to 18). Mean interval between initial and repeat vasoepididymostomy was 19 months (range 12 to 41). Of the patients 10 underwent unilateral and 8 bilateral anastomoses, for a total of 26 repeat anastomoses. Overall patency rate was 66.7% (12 of 18) with sperm in the ejaculate in 75, 85 and 43% of patients in groups 1, 2 and 3, respectively. The patency rates according to the levels of the anastomosis were 66.7, 62.5 and 100% in the caput, corpus and cauda, respectively. Natural conception occurred in 3 of 12 couples (25%, 2 caput and 1 caudal anastomosis) during a mean followup of 23 months (range 13 to 34). All 3 cases had congenital obstruction. Pregnancy was achieved in 2 group 1 cases with cryopreserved sperm extracted at repeat vasoepididymostomy, and in 1 case each in groups 1 and 2 with microsurgical epididymal sperm aspiration and intracytoplasmic sperm injection. CONCLUSIONS: After repeat vasoepididymostomy two-thirds of men have sperm in the semen. Natural conception occurred in 25% of patients (3 of 12) followed for more than 18 months. Inability to establish pregnancy in the remaining 7 of 9 patients with sperm in the semen with a followup longer than 18 months may be due to epididymal dysfunction or partial obstruction and subsequent poor sperm quality. Aspiration of motile sperm and cryopreservation were possible in 11 of 18 cases at repeat vasoepididymostomy and should be recommended in case azoospermia remains or occurs after surgery. It appears worthwhile to offer patients repeat vasoepididymostomy after a failed initial procedure.     

Animal models for epididymoepididymostomy. Development of an alternative microsurgical procedure for vasoepididymostomy.

The present success rate for high level microsurgical vasoepididymostomy in patients with obstructive azoospermia is generally poor in comparison with more distal vasoepididymal bypasses, suggesting that the development of a high level bypass method which preserves the distal maturation and storage functions of the epididymis might increase the fertility success rate. To achieve this we have developed a segmental bypass of the distal caput-proximal corpus regions of the epididymis (epididymoepididymostomy) using the rat and rabbit as animal models. In this procedure the epididymides of 11 adult male Sprague-Dawley rats were exposed through a scrotal incision and a convolution of the duct in the proximal corpus region was attached to an opened convolution in the mid-caput epididymides using a standard microsurgical technique. Each male was rested for at least 3 months after the microsurgical bypass operation to allow the preoperative sperm contents of the caudal storage region to be replaced by post-bypass spermatozoa. Six of the 11 rats were proven fertile after surgery by siring litters from mating trials up to 11 months later. The patency of anastomoses was confirmed in 3 animals by laparotomy and recovery of large numbers of sperm with normal motility from the cauda epididymidis distal to the anastomosis site and also from the vas. Similar unilateral surgery in 2 adult male rabbits resulted in normal post-operative semen profiles in 1 and an in vivo fertilisation rate of 100% from 1 mating trial 8 months after surgery. The successful development of a reliable animal model for epididymoepididymostomy provides an experimental tool for studying the function of the epididymis. This technique may also have clinical application as an alternative to high level vasoepididymostomy in selected patients with obstructive azoospermia.     

Outcomes for vasovasostomy performed when only sperm parts are present in the vasal fluid

This article reviews the outcomes for vasovasostomy (VV) when only sperm parts were present in the vasal fluid. Thirtyfour patients who underwent bilateral (31) or unilateral (3) VV had either sperm parts bilaterally or sperm parts on 1 side and intravasal azoospermia on the contralateral side. Two of the procedures (1 unilateral, 1 bilateral) were repeat procedures. Patient and partner age were 42 +/- 1.2 (range: 34-54 and 33 +/- 0.9 (range: 23-42) years, respectively. Follow-up was 10 +/- 1.8 months. The obstructive interval was 10 +/- 0.9 (range: 4-27) years. The patency rate was 76% (26/34). The obstructive interval ranges for patent cases versus not-patent cases were 3 to 21 and 3 to 27 years, respectively. The obstructive interval did not differ between the patent and not-patent groups (9 years vs 11 years, P = 0.3978). The pregnancy rate for those with sufficient follow-up was 35% (7/20). Of the 8 failed cases, 2 had only an occasional sperm head bilaterally and 1 other had an occasional sperm head on 1 side and contralateral intravasal azoospermia. If these 3 cases were excluded, then the patency rate was 84% (26/31). The patency rate for VV performed when only sperm parts were present in the vas fluid was lower than previously reported patency rates with complete sperm but at least as good as most surgeons' experience with vasoepididymostomy. The pregnancy rate was also less than previously reported pregnancy rates with complete sperm. These data suggest that VV is indicated only when sperm parts are noted in the vasal fluid. There does not appear to be a threshold obstructive interval above which VE would be indicated in this setting. If only an occasional sperm head is noted in the vasal fluid, then the surgeon should consider vasoepididymostomy.     

Need for sperm retrieval and cryopreservation at vasectomy reversal

PURPOSE: Controversy exists on whether to obtain sperm for cryopreservation routinely at vasectomy reversal. With recent improvements in in vitro fertilization with intracytoplasmic sperm injection, it is now possible to obtain a small amount of testicular tissue for cryopreservation in the event of reversal failure. However, to our knowledge no studies exist of who is most likely to benefit from this procedure. MATERIALS AND METHODS: We reviewed 84 consecutive vasectomy reversals performed by 1 surgeon (J. I. S.) between July 1996 and March 2000 with followup available for 77. We grouped cases by procedure as vasovasostomy, vasoepididymostomy and vasovasostomy with vasoepididymostomy as well as bilateral or unilateral. Sperm was retrieved at reversal in 15 of 46 vasovasostomy (none used), 11 of 18 vasoepididymostomy (3 used) and 13 of 20 vasovasostomy with vasoepididymostomy (none used) cases. RESULTS: The overall anastomotic patency rate after unilateral or bilateral vasovasostomy, unilateral vasovasostomy with contralateral vasoepididymostomy and unilateral or bilateral vasoepididymostomy was 96%, 83% and 57%, respectively. The natural pregnancy rate without in vitro fertilization was 57%, 50% and 14%, respectively. The most recent vasoepididymal anastomoses were performed by the Berger triangulation technique with a 78% patency and 25% pregnancy rate. Only 8% of men with banked sperm eventually used it for assisted reproductive techniques, in whom unilateral or bilateral vasoepididymostomy failed in all. CONCLUSIONS: We currently do not recommend routine sperm retrieval for cryopreservation in men who undergoing vasovasostomy. We encourage men who require bilateral vasoepididymostomy to bank sperm at reversal. In men who undergo vasovasostomy with vasoepididymostomy we base the decision on preoperative counseling and intraoperative findings.     

附睾输精管吻合术治疗梗阻性无精子症

目的探讨附睾输精管吻合术在梗阻性无精子症治疗中的作用。方法选择23例确诊为梗阻性无精子症并初步怀疑为附睾水平梗阻的患者进行阴囊探查，观察睾丸、附睾及输精管情况，对其中19例确定为附睾水平梗阻并在附睾液中找到活精子的患者用8-0尼龙线施行双侧或单侧附睾输精管端侧吻合术，术后随访其疗效。结果19例获随访8～34个月，9例(47％)于术后3～9个月从精液中检出活精子，其中5例配偶受孕成功。结论阴囊探查简单、易行，有助于梗阻性无精子症的诊断和治疗，附睾输精管吻合术治疗梗阻性无精子症取得初步效果，值得进一步探讨。     

附睾梗阻性无精子症的手术治疗

目的 评价附睾梗阻性无精子症(EOA)的手术效果和影响因素. 方法回顾性分析51例EOA患者的临床资料.患者均在硬膜外麻醉下行阴囊探查术.放大镜辅助下,行单层纵向2针套叠式输精管附睾吻合术(LIVE).收集资料包括手术方法、随访时间、术后精子数平均值、a级精子百分率及复通率和受孕率. 结果 平均手术时间(134±36)min.49例一侧或双侧附睾有精子检出,其中1例一侧附睾对侧输精管检出精子;2例附睾未检出精子.49例附睾找到精子者中,48例行单侧或双侧LIVE,1例行单侧LIVE对侧输精管端端吻合.48例行单纯LIVE者失访4例,余44例随访7～17个月,32例精液中检出精子,复通率为72.7%;精子总数平均为(24±23)×106个;28例(87.5%)精液中检出a级精子,a级精子平均为(12.0±11.2)%.39例随访12个月,其中10例妊娠,受孕率为25.6%.术后妊娠与吻合口位置有关,本组妊娠均为吻合部位在尾部者. 结论 放大镜辅助下的LIVE操作简单、费用低,并能取得满意的复通率和受孕率;术中应考虑吻合口位置对妊娠的影响.     

Vasoepididymostomy for Vasectomy Reversal: A Critical Assessment in the Era of Intracytoplasmic Sperm Injection

Purpose

We compared vasoepididymostomy to microsurgical epididymal sperm aspiration and intracytoplasmic sperm injection for treatment of epididymal obstruction secondary to vasectomy.

Materials and Methods

Results in patients who underwent vasoepididymostomy for vasectomy reversal at our institution were compared to those reported previously for microsurgical epididymal sperm aspiration and intracytoplasmic sperm injection performed for obstructive azoospermia. The pregnancy rates, delivery rates, complications, cost per procedure and cost per delivery were compared. A cost per newborn analysis was performed using pregnancy and delivery rates, and reported cost estimates for the complications of assisted reproductive techniques.

Results

A total of 55 men underwent 58 vasoepididymostomies in an attempt to restore fertility after vasectomy. Median followup was 19 months (range 0 to 115). Median obstructive interval was 12 years. There were no major complications. The patency rate after 6 months was 85%. Of the couples 20 achieved 24 pregnancies and 16 had 17 live births. The pregnancy rate at 1 year was 44%. There were 4 miscarriages and there are 3 ongoing pregnancies. The live delivery rate was 36%. Assuming a 29% delivery rate for microsurgical epididymal sperm aspiration and intracytoplasmic sperm injection, the cost per newborn was $51,024, compared to $31,099 for vasoepididymostomy.

Conclusions

Vasoepididymostomy is more successful and more cost-effective than microsurgical epididymal sperm aspiration and intracytoplasmic sperm injection for vasectomy reversal. It does not expose the women to complications in the treatment of a male problem and it is indicated for treatment of epididymal obstruction secondary to vasectomy. Microsurgical epididymal sperm aspiration and intracytoplasmic sperm injection should be reserved for cases not amenable to surgical reconstruction.     

A modified vasoepididymostomy performed with the sling and blanket technique

A modification is presented for the end-to-end type of vasoepididymostomy known as the sling and blanket. We have exploited the differences in size between the vas and epididymis to gain a mechanical advantage. When the epididymis is transected the redundant tunic is preserved. The sling is created from the tunic, which is drawn forward and sutured to the vas posteriorly about 1 cm. from its cut end. The sling provides support so that the end-to-end anastomosis between the vas lumen and specific epididymal tubule may be completed in 1 plane and without rotation. The blanket is created from the remaining epididymal tunic, which is sutured anteriorly to cover the anastomosis and stabilize the vas. The procedure was performed on 8 patients with primary epididymal obstruction. The patency rate was 50% and the pregnancy rate was 25%. Although vasoepididymostomy remains a difficult microsurgical operation, this modification seems to be beneficial in selected cases.     

An assessment of the fertilizing ability of spermatozoa in the epididymis of the marmoset monkey (Callithrix jacchus)

The fertilizing ability of spermatozoa from different regions of the epididymis of the marmoset monkey, Callithrix jacchus , was assessed by determining their rate of fusion with zonaless hamster ova in vitro. This technique tests for functional competence and was validated using epididymal spermatozoa of the hamster whose fertility have been measured previously by in vivo fertilization experiments. The results suggest that some marmoset spermatozoa first acquire the ability to fertilize in the distal caput and proximal corpus epididymidis although the majority become fertile on reaching the proximal cauda region. Acquisition of fertilizing capacity was associated with a change in the degree and character of sperm motility. However, it is considered that modifications to the sperm plasmalemma which allow capacitation and the acrosome reaction to occur are of primary importance for sperm fertility. The development of sperm fertilizing ability in the marmoset is discussed in relation to that in other primates.     

Prospective analysis of outcomes after microsurgical intussusception vasoepididymostomy

OBJECTIVE: To prospectively analyse the outcomes of microsurgical vasoepididymostomy using the intussusception technique, as vasoepididymostomy is considered the most challenging reconstructive microsurgery in urology. PATIENTS AND METHODS: From 1998 to 2003, of 324 men with obstructive azoospermia who had undergone microsurgical reconstruction of the reproductive tracts, 68 (21%) had intussusception vasoepididymostomy bilaterally or unilaterally in a functionally solitary testis. The outcomes of these patients were analysed prospectively. RESULTS: The mean age was 39.8 years for the men and 31.8 years for their partners. The causes of obstruction were after vasectomy in 31%, infection in 22%, iatrogenic in 19%, trauma in 1.5%, and idiopathic in 27%. The median duration of obstruction was 18.8 years; 37% of patients had had previous failed attempts at reconstruction. The mean (range) follow-up was 15.2 (1-36) months. The overall patency (>10 000 sperm/mL) rate was 84% (53/63). Patency was achieved in 60% (38/63) of men at 1 month after surgery. The mean best sperm count was 12.8 (0.01-80) x 10(6)/mL, with a 21 (0-30)% motility. Among patients with a follow-up of > 1 year, the natural paternity rate was 40%. The median time to achieve a natural pregnancy was 14.3 (3-30) months. Pregnancy was achieved with in vitro fertilization or intracytoplasmic sperm injection in 31% of cases, all using fresh ejaculated sperm. CONCLUSIONS: A favourable patency and pregnancy rate can be achieved using microsurgical intussusception vasoepididymostomy. Even when assisted-reproductive technology is needed, fresh ejaculated sperm can be used without requiring a subsequent sperm retrieval procedure. Thus, microsurgical reconstruction of the reproductive tract should be primary therapeutic method in cases of azoospermia from epididymal obstruction.     

Correlation between changes in rat sperm membrane lipids, protein, and the membrane physical state during epididymal maturation.

An enriched plasma membrane fraction was isolated from caput, corpus, and cauda rat spermatozoa and analyzed for lipid and protein content, thermal phase transition temperature using electron paramagnetic resonance spectroscopy (EPR), and enzymatic assays of calcium-dependent ATPase activity. Based on sperm concentration, total membrane phospholipid, cholesterol, and protein content declined as sperm passed through the epididymis. A more refined analysis of the bulk plasma membrane phospholipid revealed that approximately 56% of the phospholipid consisted of choline (PC) and ethanolamine (PE) phosphoglycerides; the remainder consisted of sphingomyelin (SM), phosphatidylserine (PS), and diphosphatidylglycerol (DPG). The mole percent of PE increased in sperm proceeding from the caput to the corpus epididymis and then declined from the corpus to the cauda epididymis. The phospholipid-bound fatty acids consisted primarily of palmitate (C16:0) and stearate (C18:0), with a significant increase in the mole percent of the docosapentenoyl acyl group (C22:5) in cauda sperm. Arrhenius' plots of the EPR peak height signals using the lipid soluble spin label, 5-doxyldecane, and the calcium-dependent ATPase activity as a function of temperature demonstrated a change in the apparent fluidity of the membrane and energy of activation of the calcium-dependent ATPase associated with the three sperm membrane preparations. These data suggest that the apparent fluidity and biochemical composition of the sperm membrane change during epididymal maturation.     

Microsurgical vasoepididymostomy with sperm cryopreservation for future assisted reproduction

BACKGROUND: Although obstructive azoospermia is treatable with microscopic seminal reconstruction, the number of patients who choose to undergo vasoepididymostomy is limited because of recent advances in assisted reproductive technology (ART). We attempted to define the outcome of surgical reconstruction in patients with suspected epididymal obstruction and no previous history of vasectomy. METHODS: We described 40 eligible end-to-side vasoepididymostomy procedures performed on 24 azoospermic patients who had either bilateral or unilateral epididymal obstruction. RESULTS: The overall patency rate following surgery was 54% (13/24) and for four patients (17%), natural intercourse resulted in pregnancy. Two pregnancies were initiated with intracytoplasmic sperm injections using frozen sperm collected during vasoepididymostomy. CONCLUSIONS: In the era of modern ART, microsurgical vasoepididymostomy with cryopreservation of sperm collected during the operation is recommended for patients with epididymal obstructions.     

Microsurgical vasoepididymostomy: a prospective randomized study of 3 intussusception techniques in rats

PURPOSE: Vasoepididymostomy is a technically challenging but cost-effective treatment for obstructive azoospermia. We evaluated the outcomes of 3 intussusception vasoepididymostomy techniques, namely 3 suture triangulation, 2 suture transverse and a new 2 suture longitudinal technique. MATERIALS AND METHODS: Male Wistar rats were randomized into 4 experimental and 1 control groups. After 3 weeks of vasal obstruction bilateral vasoepididymostomy was performed. In group I, 3 sutures were placed in triangular fashion. In group II, 2 sutures were placed perpendicular to the tubule. In group III, 2 sutures were placed longitudinal to the tubule. The tubules were then opened in the direction of the needles and anastomosed to the vasa. After 5 months patency was evaluated in blinded fashion. RESULTS: The functional patency rate (presence of motile sperm in the vas) was 64%, 64% and 93% in groups I to III, respectively (p <0.001). As evaluated by methylene blue retrograde vasography toward the epididymis, the mechanical patency rate was similar for the 3 techniques, that is 86%, 86% and 93% in groups I to III, respectively. The sperm granuloma rate was significantly lower in group III (36%, 21% and 0% in groups I to III, respectively, p <0.001). CONCLUSIONS: Transverse 2 suture vasoepididymostomy has a patency rate similar to that of the 3 suture technique. Our new 2 suture longitudinal technique, which allows a larger opening in the epididymal tubule for anastomosis, is superior to the 2 and 3 suture techniques with respect to the patency and sperm granuloma rates.     

Development of sperm motility patterns in the murine epididymis

The maturation of sperm motility in the epididymis of the mouse was assessed using a computer-assisted sperm analysis system. Spermatozoa were immotile in the most proximal regions of the epididymis but developed motility rapidly in the proximal caput epididymis; the percentage motility remained high thereafter. In the caput, flagellar beat was erratic with little progression, but in the proximal corpus region circular movement patterns were reflected in reduced linearity (LIN) and straightness (STR) of the sperm tracks, although velocities were little changed and wobble (WOB) increased. In the mid-corpus region, however, all velocities, LIN, STR and WOB, increased markedly. In more distal regions there was little change in these parameters. Distribution curves of the kinematic parameters of spermatozoa obtained from each region indicated that the most heterogeneous population was that from the mid-corpus epididymis; the most homogeneous was that from the mid-cauda region. Individual sperm tracks revealed slowly progressing spermatozoa in the distal caput, transforming to motion in small circles, interrupted by more linear progression. More distally, linear progression was interrupted by looping movements and a generally progressive path was observed thereafter, with less deviation from the average path as the spermatozoa matured. Spermatozoa displaying motion compatible with passing the uterotubal junction were first found in the proximal corpus epididymis, in agreement with earlier in-vivo fertilization studies on where fertilizing capacity is achieved with epididymal spermatozoa.     

计算机辅助分析人、家兔、大鼠和小鼠附睾精子运动能力

本研究应用计算机辅助精子分析（ＣＡＳＡ）定量分析了人、家兔、大鼠和小鼠精子附睾成熟过程中，精子运动能力的发生和发展。同时对这几种动物和人进行了系统分析和比较。结果表明：在不同种属之间，其运动的发生和发展具有一定的差异；各种不同种属动物精子在各自附睾成熟过程中，其运动能力的两个方面参数，运动速度和运动方式的发展是不平行的；附睾尾部精子的运动能力（包括运动速度和直线程度）最强。     

Investigation of epididymal sperm maturation in the golden hamster

During passage of hamster spermatozoa through the epididymis their maturation is shown to involve changes in the sperm head, midpiece (mitochondria) and tail. The sum of these changes results in a dramatic increase in the fertilizing potential of the spermatozoa. When comparable numbers of spermatozoa from the caput or corpus epididymis were injected into one uterine horn of mature females, following ovulation induction, and spermatozoa from the cauda epididymis were injected into the contralateral horn, no fertilization was observed with caput epididymal spermatozoa, 1.7% of oocytes were fertilized by corpus epiddymal spermatozoa, whereas 79.5% fertilization was obtained with cauda epididymal spermatozoa. Total sperm numbers increased from caput to corpus to cauda [28.3 ± 12.2, 40.6 ±20.8, 1434 ±62 mihon, respectively]. The percentage of progressively motile spermatozoa increased from 27.9 ±6.4 to 33.8 ± 4.8 to 70 ± 10.7 during this passage. Viability, measured by exclusion of the dye, propidium iodide, was significantly less in spermatozoa from the cauda than from the proximal or mid-caput epididymis. The percentage of the live cells that were stained intensely by rhodamine-123 (a measure of mitochondrial membrane potential) increased during epididymal passage from 22.8 ±7.8% in the proximal caput epididymis to 57.2 ± 16.5% in the cauda epididymis. Staining with acridine orange (a measure of DNA packaging in the sperm head) indicated an increase in chromatin condensation in cauda epididymal spermatozoa, when compared to those obtained from the caput or corpus.     

Erratum

During passage of hamster spermatozoa through the epididymis their maturation is shown to involve changes in the sperm head, midpiece (mitochondria) and tail. The sum of these changes results in a dramatic increase in the fertilizing potential of the spermatozoa. When comparable numbers of spermatozoa from the caput or corpus epididymis were injected into one uterine horn of mature females, following ovulation induction, and spermatozoa from the cauda epididymis were injected into the contralateral horn, no fertilization was observed with caput epididymal spermatozoa, 1.7% of oocytes were fertilized by corpus epididymal spermatozoa, whereas 79.5% fertilization was obtained with cauda epididymal spermatozoa. Total sperm numbers increased from caput to corpus to cauda [28.3 ± 12.2, 40.6 ± 20.8, 144 ± 62 million, respectively]. The percentage of progressively motile spermatozoa increased from 27.9 ± 6.4 to 33.8 ± 4.8 to 70 ± 10.7 during this passage. Viability, measured by exclusion of the dye, propidium iodide, was significantly less in spermatozoa from the cauda than from the proximal or mid-caput epididymis. The percentage of the live cells that were stained intensely by rhodamine-123 (a measure of mitochondria1 membrane potential) increased during epididymal passage from 22.8 ± 7.8% in the proximal caput epididymis to 57.2 ± 16.5% in the cauda epididymis. Staining with acridine orange (a measure of DNA packaging in the sperm head) indicated an increase in chromatin condensation in cauda epididymal spermatozoa, when compared to those obtained from the caput or corpus.     

Loss of sperm surface sialic acid induces phagocytosis: an assay with a monoclonal antibody T21, which recognizes a 54K sialoglycoprotein

Using a monoclonal antibody T21, we reported that a mouse sperm maturation-associated antigen sialoglycoprotein of 54000 daltons (54K sialoglycoprotein) was secreted at the distal caput to proximal corpus epididymidis and that the 54K sialoglycoprotein had a hidden determinant (cryptodeterminant), which could be eliminated by sialidase treatment (Toshimori et al. (1988): Histochemistry 90:195-200; (1990a): Biol Reprod 42:151-160; (1990b): Arch Histol Cytol 53:339-349). This study evaluated the mouse sperm susceptibility to phagocytosis by macrophage in vitro. Comparisons were made between sperm from the caput epididymidis (caput sperm) incubated in modified Krebs Ringer's solution (MKR) and caput sperm incubated in MKR containing cauda fluid, and between sialylated (sialidase-untreated) sperm from the corpus and cauda epididymidis (corpus/cauda sperm) and desialylated (sialidase-treated) corpus/cauda sperm. The results showed that macrophages were least actively engaged in phagocytosis for caput sperm incubated in MKR containing cauda fluid, and most active for desialylated corpus/cauda sperm. Incubation of caput sperm in MKR containing cauda fluid revealed that the 54K sialoglycoprotein in cauda fluid could be bound to the flagellar surface of caput sperm. These results together with previous findings strongly suggest that the 54K sialoglycoprotein bound to immature sperm during maturation in the epididymis is implicated in the protection of sperm from phagocytosis with the aid of sialic acid residues.