Contractility of seminiferous tubules as related to sperm transport in the male

The mammalian testes have several mechanisms to propel the nonmotile spermatozoa in the seminiferous tubules through the rete testis into the epididymis. These include (a) contractions of the testicular capsule and the seminiferous tubules and (b) fluid flow through the excurrent ducts resulting from active transport of fluids and electrolyte into the seminiferous tubules from the extracellular space. The efflux of fluids and sperm from the testis appears to closely parallel spermiation. An increased output of fluid may result from prostaglandins (PGF2 alpha) and possibly oxytocin (not all species respond to oxytocin) as a result of capsular contractions compressing and expelling the fluid from the tubules. Seminiferous tubular contractions do not result from nervous stimulation but are linked to PGs and cyclic nucleotide generation. They are regulated to some extent by androgens and the lesser response of the tubules to 5 alpha-dihydrotestosterone compared to testosterone can be explained by their interaction with androgen binding protein and their action on phospholipase A2 activity for PG synthesis.     

新生小鼠睾丸组织和作为异种移植物的人类胎儿睾丸组织在免疫缺陷小鼠中的发育情况(英文)

目的:采用同种和异种睾丸组织移植的方法,研究新生小鼠睾丸组织及人类未成熟睾丸组织异种移植物在免疫缺陷小鼠体内发育不同时期生精细胞的组成和基因表达情况中生精细胞的发育情况。方法:以免疫缺陷小鼠为受体,新生小鼠睾丸组织和人类未成熟睾丸组织为供体,分别进行同种和异种移植。通过对移植物的组织形态学观察和分子生物学检测,对各个时期同种移植物中的生精细胞组成及其特异性基因的表达情况进行评估并与末受损小鼠的情况相比较;对人睾丸组织异种移植物的存活及其生精细胞在异体异位的发育情况进行探讨。结果:新生小鼠睾丸组织在成年雄性去势免疫缺陷小鼠体内的发育状况在移植开始的一个阶段与在体睾丸组织的发育情况基本相同,各级生精细胞的出现及其基因表达均与在体睾丸组织中相类似,而移植7-8星期后生精小管发生退化现象。人未成熟睾丸组织在受体中存活并且进一步生长;组织学观察还发现,生精细胞的发育速度与在体相比具有加速的倾向。结论:新生小鼠睾丸组织同种移植物的发育与在体情况基本相同,而人类未成熟睾丸组织异种移植物的发育与正常生理状态相比较呈现出加速的倾向。     

Transformation,migration and outcome of residual bodies in the seminiferous tubules of the rat testis

Experiments were performed to study the transformation, migration and outcome of residual bodies (RBs) in the seminiferous tubules of the rat testes. One part of the testes from adult Sprague–Dawley rats was used to generate paraffin sections to observe RBs and RB precursors through specific staining, and the other part of the testes was used to generate ultrathin sections to observe RBs under a transmission electron microscope. Deep blue particles of different sizes were observed in some seminiferous tubules through specific staining for RBs and RB precursors. These particles first appeared in the seminiferous tubules at stage I of the spermatogenic cycle, and after spermiation, the particles travelled rapidly towards the deeper region of the seminiferous epithelium and soon appeared close to the basement membrane of the seminiferous tubule. All of the particles in the tubules disappeared at stage IX. Using transmission electron microscopy, components of different electron densities were observed in the RBs on the surface of the seminiferous epithelium, all of which gradually formed in the cytoplasm of spermatozoon in later stages of spermiogenesis. After the spermatozoa were released, the RBs in the epithelium travelled quickly to the edge of the tube and were gradually transformed into lipid inclusions. These lipid inclusions ultimately became lipidlike particles. The lipidlike particles were discharged into the interstitial tissue. RBs initiate their own digestive process before their formation during spermiation in the rat testes. After spermiation, the RBs transform into lipid inclusions and finally into lipidlike particles. These lipidlike particles can be eliminated from the seminiferous tubules.     

Antioxidant effect of manganese on the testis structure and sperm parameters of formalin‐treated mice

Manganese inhibits oxidative stress damage. The aim of this study was to investigate the protective role of manganese on testis structure and sperm parameters in adult mice exposed to formaldehyde (FA). Twenty adult male NMRI mice were selected and randomly divided into four groups: (i) control; (ii) sham; (iii) ‘FA’‐exposed group; and (iv) ‘FA and manganese chloride’‐exposed group. The FA‐exposed groups received 10 mg kg^?1 FA daily for 14 days, and manganese chloride was just injected intraperitoneally 5 mg kg^?1 on 2nd weeks. Mice were sacrificed, and spermatozoa were collected from the cauda of the right epididymis and analysed for count, motility, morphology and viability. The other testicular tissues were weighed and prepared for histological examination upon removal. Seminiferous tubules, lumen diameters and epithelium thickness were also measured. The findings revealed that FA significantly reduced the testicular weight, sperm count, motility, viability and normal morphology compared with control group (P ≤ 0.05). In addition, seminiferous tubules atrophied and seminiferous epithelial cells disintegrated in the FA group in comparison with the control group (P ≤ 0.05). However, manganese improved the testicular structure and sperm parameters in FA‐treated mice testes (P ≤ 0.05). According to the results, manganese may improve and protect mice epididymal sperm parameters and testis structure treated with FA respectively.     

Serum reproductive hormone levels and sperm production in male adult rats after treatment with arresting, a fraction obtained from seminiferous tubules conditioned medium

This study used seminiferous tubule (ST) segments from adult rats to condition culture medium that had been concentrated, size fractioned and administered 10-84 days to adult rats by subcutaneous or intratesticular injection and the effects on testes weight, testosterone, luteinizing hormone (LH) and FSH levels and (homogenization-resistant) epididymal sperm count were determined. The conditioned medium obtained 2 days after culture of ST was fractionated in a 30-100 kDa component. The fraction was injected subcutaneously or intratesticularly. This factor(s), named arresting, decreases sperm count in the epididymis from 13 days to 84 days of treatment without changes in serum LH or testosterone levels. The results of the present study suggest that arresting acts on spermiogenesis/spermiation and/or the entry of sperm into the epididymis from the efferent ductules.     

The effect of p-nonylphenol on the fertility potential of male rats after gestational, lactational and direct exposure

There is growing concern that abnormalities in male reproductive health are becoming more frequent. The most fundamental change has been the striking decline in sperm counts and semen quality. The effect of maternal exposure of rats to the oestrogenic environmental substance p-nonylphenol (p-NP) was determined in this study. Exposure to p-NP for the experimental period impaired general growth. The lower testicular mass indicated a direct toxic effect on the testis in animals exposed to p-NP during foetal life, the postnatal period and after weaning until termination at 10 weeks of age. The epididymal mass was also negatively affected by p-NP; this was supported by the decrease in the epididymal ratio. The total cauda epididymal sperm count was significantly lower in the 250 mg kg-1 p-NP dosage group compared to the control and 100 mg kg-1 p-NP groups. The overall lower sperm count with increased p-NP concentrations corresponded with the decreased testicular and epididymal masses. This emphasized the toxicity of p-NP on both testis and epididymis. Seminiferous tubule diameter, lumen diameter and seminiferous epithelium thickness were smaller in the exposed groups, even at the low dose level. These histological measurements further supported the finding of a low testicular mass. In spite of the measurements being smaller, p-NP had no effect on the stages of spermatogenesis except for one animal with disrupted spermatogenesis in some tubules, while others were normal.     

Protection of spermatogenesis against gamma ray-induced damage by granulocyte colony-stimulating factor in mice

The radioprotective effects of granulocyte colony-stimulating factor (GCSF) were further investigated with respect to the testicular system. Recombinant human GCSF (100 μg kg(-1) body weight/day) was administrated to male C3H/HeN mice by subcutaneous injection for three consecutive days before pelvic irradiation (5 Gy) and histopathological parameters were assessed at 12 h and 21 days post-irradiation (pi). The GCSF protected the germ cells from radiation induced- apoptosis (P < 0.01 vs. irradiated group at 12 h pi). GCSF remarkably attenuated radiation-induced reduction in testis weight, seminiferous tubular diameter, seminiferous epithelial depth and sperm head count in the testes (P < 0.05 versus irradiated group at 21 days pi). Repopulation index and stem cell survival index of the seminiferous tubules were increased in the GCSF-treated group when compared with the radiation group (P < 0.01). The frequency of abnormal sperm in the GCSF group was lower than that in the irradiated group at 21 days pi (P < 0.01). The decrease in the sperm count and in sperm liability in the epididymis caused by irradiation was counteracted by GCSF. The present study suggests that GCSF protects from radiation-induced testicular dysfunction via an anti-apoptotic effect and recovery of spermatogenesis.     

6‐Gingerol‐rich fraction prevents disruption of histomorphometry and marker enzymes of testicular function in carbendazim‐treated rats

Previous investigations demonstrated that 6‐gingerol‐rich fraction (6‐GRF) prevented testicular toxicity via inhibition of oxidative stress and endocrine disruption in CBZ‐treated rats. The influence of 6‐GRF on alterations in histomorphometry and marker enzymes of testicular function in CBZ‐treated rats which hitherto has not been reported was investigated in this study. The animals were orally administered either CBZ (50 mg/kg) alone or in combination with 6‐GRF (50, 100 and 200 mg/kg) for 14 consecutive days. Histomorphormetric analysis demonstrated that 6‐GRF significantly prevented CBZ‐mediated increase in the organo‐somatic index of the testes and seminiferous tubular diameter as well as the reduction in epithelium height and tubular length of testes in the rats. Similarly, 6‐GRF ameliorated CBZ‐induced disruption in the epithelium height as well as in the proportion of tubule and interstitium of the epididymis the treated rats. Furthermore, 6‐GRF prevented CBZ‐mediated increase in testicular acid phosphatase activity and the decrease in testicular alkaline phosphatase, aminotransferases, glucose‐6‐phosphate dehydrogenase and lactate dehydrogenase activities. Moreover, 6‐GRF ameliorated CBZ‐induced reduction in the testicular and epididymal sperm count and sperm motility in the treated rats. Conclusively, 6‐GRF enhances key functional enzymes involve in spermatogenesis and maintains histo‐architecture of testes and epididymis in CBZ‐treated rats.     

Pattern of Sertoli cell degeneration in cryptorchid prepubertal tests

Seventy-three testicular biopsies from 54 children (aged 2 months-14 years) with undescended testes were examined by light and electron microscopy. The biopsies included abdominal, inguinally fixed, inguinally moveable, and retractile testes. Alterations in Sertoli cell morphology were found in all biopsies. The alterations included dilated elements of rough endoplasmic reticulum, vacuolization of the cytoplasm, mitochondria with poorly preserved cristae, increase in electron density of the matrix, elongation of the nuclei, and irregularities of the nuclear membrane. According to the numerical appearance of these cells and to the extent of lesions in single Sertoli cells, seven phases in the continuous process of tubular alteration were distinguished. The most severe tubular damaged (phase VII) occurred when the seminiferous epithelium consisted exclusively of necrotic cells. All phases of tubular alterations were seen regularly in each of the biopsies investigated. Germ cells occurred only in phases I-IV and were never observed in tubules in phases V-VII. Significant differences became evident between inguinal and retractile testes by morphometric evaluation. It was demonstrated that the number of germ cells per cross-sectioned tubule (S/T value) correlated negatively with the percentage of tubules in phases V-VII. In contrast to inguinal testes, a complete absence of Sertoli cells and an S/T value less than 0.1 were never found in retractile testes and the percentage of tubules in phases V-VII was reduced significantly compared with inguinal testes. Our findings indicate that (i) maldescended testis in patients between 1 and 15 years-of-age is associated with a special pattern of Sertoli cell degeneration; (ii) Sertoli cell degeneration is a continuous process, which can lead eventually to complete dissolution of the seminiferous epithelium; (iii) total degeneration is not related to age but is dependent on testicular position; (iv) a defined phase of degeneration excludes germ cell development, and therefore enhanced Sertoli cell degeneration in cryptorchid testes must also account for the reduction in germ cell number.     

Cycloheximide prevents production of arresting, a fraction of 30-50 kDa obtained from seminiferous tubule conditioned medium

Aim: To evaluate the effect of a protein synthesis inhibitor cycloheximide on arresting activity in spermatogenesis and sperm count in male rats. Methods: The study used seminiferous tubule (ST) segments from adult rats cultured in vitro with or without cycloheximide to condition culture media, which have been concentrated, size fractioned (30-50 kDa) and administered 7 days to adult rats by intraperitoneal injections. The effects on testicular and epididymal weights, spermatogenesis and epididymal sperm count were determined. Results: The fraction (30-50 kDa), named arresting, obtained from the culture without cycloheximide decreased testicular and epididymal weights (P＜0.01) and reduced the epididymal sperm count significantly. Study of the spermatogenic cycle by transillumination showed spermatogenic arrest at stage VⅡ in rats treated with arresting compared to that observed in controls. The length of stage VⅡ in the group receiving the seminiferous tubules culture media with cycloheximide (30-50 KDa CHX-STCM fraction) was similar to control. Conclusion: The difference in the effect may be the result of the presence or absence of arresting, a protein secreted by the tubules. (Asian J Androl 2004 Dec;6:359-364)     

Age-related variation in seminiferous tubules in men. A stereologic evaluation

Tubular boundary tissue and seminiferous epithelia were evaluated stereologically in testes from 28 men aged 20 to 48 years and 28 men aged 50 to 90 years. Testes obtained at autopsy within 15 hours of death were perfused with glutaraldehyde, embedded in Epon (Ladd Research Industries, Inc., Burlington, VT), sectioned at 0.5 micron, and stained with toluidine blue. Volume densities (percentage of the testicular parenchyma) of various parameters determined by point counting and diameter measurements were used to calculate total volumes, length of tubules, and number of cells. Electron microscopy was used to determine the volume density of myoid cells in the boundary tissue. Significant (P less than 0.01) age-related reductions occurred in paired testicular weights, paired parenchymal weights, total volume of seminiferous tubules and of seminiferous epithelium, and length of tubules. The volume density and thickness of boundary tissue increased (P less than 0.01) with age. The volume of boundary tissue per man and the volume density of myoid cells in the boundary tissue did not vary with age. Although the number of myoid cells per man tended to be lower in the older group, the number of myoid cells per cross section of seminiferous tubule was increased (P less than 0.01) in older men. The age-related thickening of the boundary tissue was not due to an increase in boundary tissue but resulted from a reduction in the length of the seminiferous tubules.     

L-肉碱在奥硝唑所致大鼠睾丸和附睾损伤中的保护作用

目的:探讨L-肉碱(LC)在奥硝唑(ORN)所致大鼠附睾和睾丸损伤中的的保护作用。方法:40只雄性SD大鼠(200～230g)随机均分为5组:①A组:给予0.5%的羧甲基纤维素钠(溶剂)灌胃;②B组:每天给予400mg/kgORN灌胃;③C组:每天给予800mg/kgORN灌胃;④D组:每天给予[ORN(400mg/kg)+LC(100mg/kg)]灌胃;⑤E组:每天给予[ORN(800mg/kg)+LC(100mg/kg)]灌胃。上述各组均连续灌胃20d,末次给药24h后,所有大鼠麻醉后处死,分别取睾丸、附睾,进行称重和HE染色,计算睾丸、附睾系数并观察睾丸和附睾病理组织学改变。结果:①与A组相比,B组睾丸、附睾系数明显降低(P<0.05);而C组睾丸、附睾系数为极显著性降低(P<0.01);D组与A组相比无差异,E组与A组相比有极显著性差异(P<0.01);②HE染色显示,与A组相比,B组睾丸生精小管内各级生精细胞排列基本整齐,部分生精小管管腔内有脱落的生精细胞,附睾管腔中精子数目下降,有时可见散在的生精细胞;C组大鼠睾丸生精小管管腔内均可见坏死脱落的生精细胞,附睾管腔中精子数目明显减少,且有较多的非精子细胞成分。D组睾丸生精小管无明显改变,附睾管腔中精子数目也未见明显下降;E组睾丸生精小管管腔内精子数目减少,可见坏死脱落的生精细胞,附睾腔中精子数目明显减少,并伴有较多的非精子细胞成分。结论:奥硝唑(ORN)可导致雄性大鼠附睾和睾丸病理组织学改变,LC对ORN引起大鼠附睾和睾丸损伤具有一定的保护作用。     

睾丸精曲小管精子发生功能量化评价法分析无精子症患者睾丸生精功能

目的 :分析无精子症患者临床和病理资料 ,研究病理学量化评价睾丸精曲小管精子发生功能的方法的临床意义。　方法 :无精子症患者 112例 ,年龄 2 2～ 4 6 (2 9.0± 4 .4 )岁 ,婚龄 2～ 12 (4 .0± 2 .8)年、病程 2～ 6 (2 .70±1.0 2 )年 ,其中原发性无精子症 96例 ,继发性无精子症 16例 ;梗阻性无精子症 7例。不育症患者精液常规检查 3次确认无精子症 ,检测性激素水平 ,常规消毒下睾丸活检病理检查 ,在高倍镜下计数每个精曲小管中各类生精细胞数 ,测定小管直径、生精上皮高度和固有层厚度 ,按制定的精曲小管精子发生功能 10分 5级分度法加以评分 ,进行统计学分析。　结果 :精曲小管生精上皮 10分分度法评分结果 ,1分 5例 (4 .5 % ) ,2分 38例 (33.9% ) ,3分 2例(1.8% ) ,4分 6例 (5 .4 % ) ,5分 2例 (1.8% ) ,6分 17例 (15 .2 % ) ,7分 6例 (5 .4 % ) ,8分 19例 (17% ) ,9分 10例(8.9% ) ,10分 7例 (6 .3% )。精曲小管精子发生功能 5级分度法结果 ,1级 5例 (4 .5 % ) ,2级 38例 (33.9% ) ,3级 33例 (2 9.5 % ) ,4级 2 9例 (2 5 .9% ) ,5级 7例 (6 .3% )。多元回归分析结果 ,精曲小管精子发生功能分级与生精上皮高度、固有层厚度、精曲小管直径和血清卵泡刺激素 (FSH)具有极显著相关性 (P <0 .0 1)。组合     

1例环状22号染色体综合征致无精子症并文献复习

目的:探讨1例患有环状22号染色体综合征的无精子症患者的临床表型和遗传学特征。方法:收集1例环状22号染色体综合征患者的临床信息,结合文献加以分析。结果:患者身材矮小,体检双侧睾丸小,质地软,精液检查示无精子症。染色体核型为46,XY,r(22)(p11,q25),性激素示睾酮低下,睾丸大体病理示组织脆、易拉断,病理镜检示生精小管内支持细胞及生殖细胞数量均减少,细胞层次变薄,生殖细胞均为精原细胞,未见精母细胞和精子细胞,完全无精子发生。部分生精小管的管壁可见间质轻度纤维化。结论:环状22号染色体综合征的临床表型基本正常,但这种遗传异常使患者的睾丸组织严重受损,生精过程被阻滞而导致了无精子症。     

Effects of date seed oil on testicular antioxidant enzymes and epididymal sperm characteristics in male mice

The aim of this study was to evaluate the effect of date seed oil (DSO) on epididymal sperm characteristics and testicular antioxidant enzymes in male mice. DSO was diluted into isotonic saline solution (0.9%) and different doses (5, 10, 15 and 20%) were prepared. Fifty male mice were divided into five groups; in four groups DSO was given by intraperitoneal injection of oil solution for 28 days. The control group was injected by isotonic saline solution without DSO. Body and reproductive organ weights, sperm characteristics (count, motility, viability and morphology) were assessed. In addition, levels of malondialdehyde (MDA), activities of superoxide dismutase (SOD) and catalase (CAT) were investigated in testes. A significant increase in sperm count, motility and viability of all treated animal groups was observed when compared with the control group ( P  < 0.05). Unlike, the percentage of abnormal sperm was significantly lower in all treated groups than in the control group ( P  < 0.05). A significant decrease in MDA levels and marked increase in SOD and CAT activities in mice treated with high doses of DSO (15 and 20%) were also noted. We suggest that DSO can improve the epididymal sperm quality and could ameliorate the testicular strategy defences.     

Human chorionic gonadotropin deteriorates the histology of rat testes

OBJECTIVES: It is not yet certain whether early hormonal treatment in cryptorchidism is safe for germ cells. We investigated the histologic effects of human chorionic gonadotropin (hCG) therapy on descended testes of rats. DESIGN AND SETTING: Thirty male Wistar albino rats were randomized into two groups. The rats of the hCG group (n=15) were administered 50 IU/kg/day hCG once daily via the subcutaneous route for 15 days. Fifteen rats received subcutaneous isotonic saline and acted as controls. At the first month, testicular tissue was obtained after scarification in both groups. The histological examination was performed to evaluate the seminiferous tubular diameter, germinal membrane thickness, and the percentage of the open seminiferous tubule lumen in each testis to compare the two groups. RESULTS: The percentage of the open seminiferous tubular lumen in testicular tissues of hCG-treated rats was higher than that of controls (p<0.05). The mean germinal membrane thickness in testicular tissues of the hCG group was statistically lower than that of the control group (p<0.05). There was no statistical difference between mean seminiferous tubular diameter in testicular tissues of hCG-treated rats and controls, as expected (p>0.05). Additionally, there were two interesting cases of Sertoli cell only appearance in the hCG group. CONCLUSIONS: We may assume that hCG impairs the seminiferous tubule histology in normal testes of rats. Thus, further experimental studies on dose dependency and the reversibility of these effects are warranted.     

Warfarin‐induced vitamin K deficiency affects spermatogenesis in Sprague‐Dawley rats

Vitamin K is present in the testes though its actual function in male reproduction is poorly understood. This study investigated the harmful effect of extrahepatic vitamin K insufficiency on the testicular structure. Sprague‐Dawley rats were fed with a diet containing warfarin for 2, 4 and 8 weeks; control animals received a standard diet without warfarin. It was found that extrahepatic vitamin K deficiency that is induced by warfarin results in histopathological features that range from delayed spermiation, presence of multinucleated giant cells in the seminiferous tubules, germ cells degeneration, asthenozoospermia, oligozoospermia and increase in the percentage of abnormal sperm morphology when compared to the controls. Data obtained from the two groups were analysed using the Student t test. It is concluded that warfarin‐induced vitamin K deficiency has a negative impact on spermatogenesis.     

The number of spermatogonia in various congenital testicular disorders

Various congenital testicular disorders, including monorchism, retractile testis, cryptorchidism and male intersex, were investigated by counting the number of spermatogonia per seminiferous tubule. The results showed that all 7 cases of monorchism had normal numbers of spermatogonia per seminiferous tubule. However, in 29 cases of a retractile testis a normal testis was observed in 13 (44.8 per cent). Therefore testicular dysgenesis is suggested to exist in more than half of cases of the retractile testis. Of 150 cases of cryptorchidism 82 were bilateral and 68 were unilateral. There was no significant difference in the number of spermatogonia per seminiferous tubule between these 2 groups. The higher the testes were located the worse the ratio of spermatogonia per seminiferous tubule. Fewer or absent spermatogonia were observed in 2 patients less than 2 years old. Of 28 contralateral scrotal testes in patients with unilateral cryptorchidism 4 (14.3 per cent) had no spermatogonia per seminiferous tubule and 8 (28.0 per cent) had a decreased number of spermatogonia per seminiferous tubule. The male intersex patients had much damage even in the scrotal testes. From these results it is suggested that these congenital testicular disorders, except monorchism, have similar histological features. Moreover, these conditions are possibly related in etiology to the phenomenon of deficient androgen stimulation.     

The effect of graded unilateral testicular biopsy on the reproductive capacity of male rats

Fifty adult rats were subjected to unilateral testicular biopsy removing either 0.01, 0.1, 0.2 or 0.3 cc of testicular parenchyma. In addition, 20 rats underwent either hemicastration or sham surgery. After a 30-day recovery period each male was housed with two cycling females for 20 days. At the end of this breeding trial the percentage of fertile males, percentage of pregnant females and resulting embryo scores (no. of embryos X size of embryos) were determined for each group of male rats. After an additional 30 days (60 days post-biopsy) a second breeding trial was performed so as to note any long-term changes in fertility. In addition to the fertility parameters, mean seminiferous tubule diameters and serum testosterone levels were noted. After the first breeding trial the percentage of fertile males and percentage of pregnant females were inversely proportional to the amount of biopsy material removed (p less than 0.05). However, the hemicastrate and sham-operated groups did not differ from the O cc control animals. The results of the second breeding trial showed a significant improvement in the percentage of females becoming pregnant (p less than 0.05) and a tendency for improvement in the percentage of fertile males when compared to data of the first breeding trial. In addition, we found the mean seminiferous tubular diameter of the biopsied testes to be inversely proportional to the size of the biopsy (p less than 0.01) with no apparent effect on the contralateral testes. We conclude that removing relatively large amounts of testicular parenchyma during unilateral testicular biopsy transiently affects male reproductive capacity, at least in the healthy animal model studied here.     

E3 ubiquitin ligase ASB17 is required for spermiation in mice

BackgroundA major goal of spermiation is to degrade the apical ectoplasmic specialization (ES) junction between Sertoli cells and elongating spermatids in preparation for the eventual disengagement of spermatids into the lumen. E3 ubiquitin ligases mediate the process of ubiquitination and the subsequent proteasomal degradation, but their specific role during spermiation remains largely unexplored.MethodsAnkyrin repeat and SOCS box protein 17 (Asb17)-knockout mice were generated via a CRISPR/Cas9 approach. Epididymal sperm parameters were assessed by a computer-assisted sperm analysis (CASA) system, and morphological analysis of testicular tissues were performed based on histological and immunostaining staining, and transmission electron microscopy (TEM). The interactions between ASB17 and Espin (ESPN) were predicted by HawkDock server and validated through protein pull-down and immunoprecipitation assays.ResultsWe report that ASB17, an E3 ligase, is required for the completion of spermiation and that mice lacking Asb17 are oligozoospermic owing to spermiation failure. ASB17-deficient mice are fertile; however, spermatids exhibit a disorganized ES junction, resulting in retention within the seminiferous epithelium. Mechanistically, ASB17 deficiency leads to excess accumulation of ESPN, an actin-binding essential structural component of the ES. We determined that ASB17 regulates the removal of the ES through ubiquitin mediated protein degradation of ESPN.ConclusionsIn summary, our study describes a role for ASB17 in the regulation of cell-cell junctions between germ cells and somatic cells in the testis. These findings establish a novel mechanism for the regulatory role of E3 ligases during spermatogenesis.