Studies on relationship between testicular capsule and sperm transport in rat testis

Aim: In SD rats, histological changes in the testis were observed after bilateral capsulotomy (of the tunica albuginea) in order to investigate the physiological role of the testicular capsule on sperm transport. Methods: Bilateral longitudinal capsulotomy was devised to disrupt the capsular contractile function. With this technique, only the tunica vaginalis and tunlca albuginea were slit open, leaving the tunica vasculosa intact to embrace the underlying testicular parenchyma. After capsulotomy, the structural changes in the seminiferous tubules, the transitional distal seminiferous segment, and the rete testis were observed. Results: In the capsulotomized testis, there was sperm retention at the transitional seminiferous segment and progressive degenerative changes in seminiferous tubules. Conclusion: The results clearly indicated that an intact testicular capsule was required for normal sperm transport from the seminiferous tubules into the rete testis. This is the first attempt to study the physiological role of the testicular capsule in intact animals.     

On the Microscopic Anatomy of the Rete Testis A Scanning Electron Microscopic and Light Microscopic Study

The microscopic anatomy of the transitional zone of the seminiferous tubules, the tubuli recti and the rete testis in adult rats was studied with histological serial sections, semithin sections and scanning electron microscopy. In paraffin section most transitional zones of the seminiferous tubules seemed to be obliterated by the modified Sertoli cells. Thinner plastic sections showed always a lumen, however. PAS - positive material, throught to represent masses of degenerating spermatozoa surrounded by Sertoli cell nuclei was found in 20% of transitional zones. About 80% of the tubuli recti had an initial widening which surrounded the bulging Sertoli cell bodies of the transitional zones.
The intratunical rete consisted of five to seven intercommunicating channels, usually of small caliber. One wide communication was regularly present, however. The extratesticular rete was usually formed of two wide cavities. From their subdivisions the five to seven ductuli efferentes arose. The rete epithelium varied from very thin squamous to cuboidal and even columnar. The epithelial cells contained a flagellum surrounded by peripheral microvilli. Loose connective tissue was found under the epithelium of all parts of the rete.     

The Connection between the Seminiferous Tubules and the Rete Testis in the Domestic Fowl (Gallus Domesticus) Morphological Study

The tubules connecting the seminiferous tubules proper to the rete testis in the fowl were studied with the aid of light and electron microscopy. The material examined ultrastructurally was fixed by vascular perfusion through the thoracic aorta. The seminiferous tubules were joined to the rete testis in three different ways; they were either linked by a terminal segment and a tubulus rectus, by a terminal segment only, or opened directly into the rete cavities. The terminal segment of the seminiferous tubules was lined with columnar cells (modified Sertoli cells). These cells were characterized by having an indented nucleus with a prominent nucleolus, many mitochondria, a sizable Golgi apparatus, electron dense bodies and many cytoplasmic protrusions into the lumen. Intraepithelial lymphocytes as well as macrophages in the lumina of the terminal segment, the tubuli recti and the rete testis were also observed. Myoid cells were found in the boundary tissue of the terminal segment.     

Functional and Structural Aspects of the Rat Seminiferous Tubules after Treatment with Exogenous Cyproterone Acetate, Testosterone, Progesterone and Oestradiol

Cyproterone acetate, testosterone propionate, progesterone and oestradiol were given to adult rats for 30 days, and the effects on the seminiferous tubules were studied. The contractility of the seminiferous tubules was not affected by cyproterone acetate or progesterone, but was totally abolished by testosterone and oestradiol. The effects of these steroids on spermatogenesis were studied histologically and electron microscopically.
Cyproterone acetate was observed to induce a clear-cut increase in the lipid content of the Sertoli cells and mitochondrial changes in all stages of the cycle of the seminiferous epithelium.
The increase of lipid content was smaller with progesterone. Oestradiol caused an accumulation of phagocytosed lipid material in Sertoli cells. These steroids did not change the protein composition of the rete testis fluid.     

Degeneration of the seminiferous epithelium with ageing is a cause of spermatoceles?

A spermatocele refers to the cystic accumulation of semen in the male reproductive tract. Although it is thought to be caused by narrowing of the lumen of the excurrent duct with resultant cystic dilatation of the duct, the pathogenesis of the narrowing remains unknown. In the present study, we histologically examined spontaneous spermatoceles in C3H/He mice to elucidate the pathogenesis of the lesions. Testes, efferent ducts, epididymides and vas deferens obtained from young and aged C3H/He mice were embedded in plastic for histological observation at the light microscopic level. It was found that spontaneous spermatoceles were localized in the rete testis and efferent ducts of aged mice, as seen in man. The dilated rete testis and efferent ducts contained many degenerated and aggregated germ cells derived from the exfoliated seminiferous epithelium in the aged testis. In particular, it was noted that the agglutinated germ cells obstructed the narrow lumen of the efferent ducts, resulting in the failure of transport of germ cells to the caput epididymis, and spermatoceles were consistently found in the region between the rete testis and the obstructed site in the efferent ducts. However, no inflammatory cell infiltration, traumatic injury or spermatic granulomas were found in the occluded region. These results suggest that agglutinated germ cells may occupy the narrow lumen of the efferent ducts, resulting in the formation of a spermatocele. It may be that a senile change to the seminiferous epithelium, which releases immature germ cells into the lumen of the seminiferous tubules, is the cause of this type of spermatocele.     

Histologic changes in the mouse testis after bilateral vasectomy

Aim: To study the effect of vasectomy on histological appearance of the testis. Methods: Parkes strain mice were used as the animal model; they were bilaterally vasectomized (Vx) or sham-operated (So) and killed at intervals of 4, 6, 9, and 12 months after the operation. Testes were excised from 5 Vx and 5 So mice at each interval and processed for histological examination. Results: Testes of So mice showed normal histological features. By contrast, marked alterations were observed in the seminiferous tubules in testes of Vx mice, except in those killed 4 months after the operation. The seminiferous epithelium in the tubules was only 2 - 3 layers thick and showed much depletion of germ cells; in severe cases, the epithelium consisted of only a thin layer of Sertoli cells, spermatogonia and a few spermatocytes. Exfoliation of germ cells, occurrence of multinucleated giant cells and vacuolated appearance of the epithelium were of common features in the tubules. Furthermore, lumen of the rete testis in Vx mice was greatly dilated and showed accumulation of spermatozoa with immature germ cells; in mice vasectomized for 6 - 12 months, several macrophages ingesting spermatozoa were often observed in the lumen of the rete testis. Spermatic granuloma was also sometimes noticed in corpus or in cauda regions of the epididymis in mice vasectomized for 6 - 12 months. Conclusion: We suggest that consequences of vasectomy should be thoroughly understood in order to make this method rather more popular as a reversible method of male contraception.     

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。     

Spermatogenesis in Snell dwarf, little and congenitally hypothyroid mice

The status of spermatogenesis in Snell dwarf, little and congenitally hypothyroid mice was studied. In all of these mice with a hormone deficiency the seminiferous tubules were smaller in size and contained fewer spermatogonia, spermatocytes, spermatids and spermatozoa than did those of normal control mice. There was no substantial difference in the Johnsen score between the hormone-deficient mice and normal control mice, but the former had underdeveloped seminiferous tubules with a corresponding paucity of germ cells, which may be partly responsible for the infertility of these mice. In the present study, growth hormone and thyroxine were administered separately to growth hormone-deficient and thyroxine-deficient mice, respectively. Such replacement therapy brought about an increase in cell counts of the seminiferous tubules and in sperm counts in both groups.     

Oxytocin promotes spermiation and sperm transfer in the mouse

Spermatogenesis is a complex process during which developing germ cells move from the base of the seminiferous tubule towards the lumen where they are shed. Studies in the rat suggest that seminiferous tubule contraction, induced by exogenous oxytocin, promotes spermiation. This study examines the role of testicular oxytocin in development of the testes, spermatogenesis and spermiation in the mouse. Groups of wild-type (WT) mice, oxytocin knockout mice (OTKO) deficient in testicular oxytocin and mice containing an oxytocin transgene (bOT4.2) that over express testicular oxytocin were killed between days 5 and 45 post partum. The testes and epididymides were removed weighed and prepared either for histological and morphometric study by light microscopy, for sperm counts (epididymis), or extracted for determination of oxytocin content (testis - day 45 only). Testicular oxytocin concentrations were significantly greater (p < 0.05) in bOT4.2 mice than in WT or OTKO mice. No differences in testicular and epididymal weight, or in diameter and area of seminiferous tubules between the mice genotypes were found at any given time. Germ cell development was similar in all genotypes and was comparable with previous studies. The timing of spermiation between the groups was significantly different (p < 0.001) with bOT4.2 < WT < OTKO and the appearance of epididymal sperm was significantly different (p < 0.05) with bOT4.2 < WT < OTKO. There were significant correlations between the percentage of tubules containing residual bodies and epididymal sperm count (p < 0.05) and between the percentage of animals containing residual bodies and the percentage of animals containing epididymal sperm (p < 0.01). These data suggest that in the mouse oxytocin, whilst not involved in germ cell development, is important in the process of spermiation and sperm transfer in the mouse.     

Effect of testicular capsulotomy on lipid droplets in the seminiferous tubules of rats

Aim: In order to reveal the histochemical alteration that might occur during the processes of the spermatogenic disruption induced by testicular capsulotomy, the location and alteration of lipid droplets in the seminiferous tubules were observed in the present study. Methods: Osmium tetroxide was used to demonstrate the lipid droplets in the seminiferous tubules of capsulotomized and sham-operated control testes. Results: In the seminiferous tubules of the sham-operated rat testes, many small lipid droplets were located close to the basement membrane of the seminiferous tubules. But for the capsulotomized testes, the lipid droplets in the seminiferous tubules had increased in size and number, with many lipid droplets migrated towards the lumen of the tubules. Conclusion: The results indicated that a progressive fatty degeneration occurred in the seminiferous tubules after testicular capsulotomy.     

Effect of ultrasound on testicular electrolytes (sodium and potassium).

The testes of 50 rats were placed in a cup filled with water and received 1 W/cm2 of ultrasound for 15 min. Fluid was collected from the seminiferous tubules and rete testis of the treated and control groups at 1, 8, 12, and 24 hr intervals. Ultrasound increased the sodium concentration in the fluid of the seminiferous tubules, decreased the sodium concentration in the fluid of the rete testis, increased the potassium concentration in the fluid of the rete testis, and decreased the potassium concentration in the fluid of the seminiferous tubules. Fourteen, slightly sedated, monkeys (Macaca fascicularis) were treated with 1/2 W/cm2 of ultrasound for 30 min. Water was used as the coupling agent for seven monkeys and 3% NaCl was used as the coupling agent for the other seven monkeys. The efficacy of ultrasound treatment in reducing sperm count to zero and achieving zero motility was increased when 3% NaCl was used. Sperm count was at the level of presonication after 20 weeks when water was used as a coupling agent.     

S-100 Protein immunoreactivity in bovine testis

The present study deals with immunohistochemical localization of S-100 protein in the bovine testis. Immunoreactivity for the protein was seen in Sertoli cells of the seminiferous tubules and as a particularly intense staining in the terminal tubular segment (transitional region, middle portion, and terminal plug), which is mainly composed of modified Sertoli cells. Immunoreactivity was also found in epithelial cells of the straight testicular tubules and rete testis, and in the endothelium of capillaries, veins and lymphatic vessels. Although the functional significance of S-100 protein immunoreactivity in the Sertoli cells remains unclear, the present results suggest that it may be involved in the microtubule assembly-disassembly system. The specificity of the immunolabelling observed should enable the antigen and/or antibody to S-100 to be used as an investigative and diagnostic tool in the study of bovine Sertoli cell function.     

Evidence of interepithelial seminoma spread into the rete testis by immunostaining of paraffin sections with antibodies against cytokeratin and vimentin

Summary Seminomas are tumors of high proliferative activity and show a marked tendency towards local invasion with the capacity for interepithelial spread within the seminiferous tubules as well as into the rete ductules. Immunohistologic investigations were carried out on paraffin sections of 47 typical seminomas. Immunostaining with antibodies against cytokeratin and vimentin allows the convenient detection of even small rete residuals in cases of subtotal rete destruction as well as the identification of discrete interepithelial seminoma spread within the rete ductules, thus facilitating seminoma staging.     

Electron microscopic evidence for deep invaginations of the lamina propria towards the seminiferous tubule lumen in a patient with varicocele

Ultrastructural studies on biopsy tissue from the right testis of a 39-year old patient with varicocele revealed 2.5-5 microns thick invaginations of the lamina propria towards the lumen of the seminiferous tubules. These invaginations were of various lengths. The presence of invaginations was confirmed through examination of serial semi-thin sections. In some seminiferous tubules two neighbouring deep invaginations were joined together thus completely encircling and thereby separating the basal compartment, and in some cases even the adluminal compartment, of the seminiferous tubule. The invaginations were surrounded continuously by the basement membrane and contained collagen fibres, cell processes of myoid cells and in some cases also their nuclei.     

Assessment of protein synthesis and secretion by rat seminiferous and epididymal tubules in vivo

In vivo microperifbsion and micropuncture were used to study tubule protein synthesis and proluminal secretion by the male reproductive tract in vivo . Somniferous and caput and cauda epididymal tubules were perihsed for 3 h. with [³⁵S]-methionine. Perifused interstitial fluid (IF), lumen fluid (LF), and tubule extract (TE) were collected. Proteins were separated by SDS-PAGE, and autoradiograms were developed.
Trichloroacetic acid precipitable proteins in each fluid were determined and a protein synthesis index (PSI) was calculated. PSI values demonstrated that the cauda epididymis synthesized less protein in vivo than did either seminiferous or caput tubules.
Seminiferous tubules synthesized and secreted into the tubule lumen a relatively constant panel of proteins. Epididymal tubules synthesized and secreted proteins in a region-specific manner. In the caput epididymis the most prominent secreted bands were consistent with the heavy and light chains of epididymal clusterin. In the cauda epididymis, the most prominent synthesized and secreted protein was a 25 kDa protein consistent with the protein D. The above approach to studying protein synthesis and secretion will allow direct study of the physiological and path physiological effects on this important epithelial hnction in vim     

Ontogeny and cellular origin of an interleukin-1 -like factor in the reproductive tract of the male rat

We have recently isolated an interleukin-1 (IL-1)-like factor from the rat testis, which originates from the seminiferous tubules and is a protein with an MW of 17,000 and a pI of 5-6. This paper reports on the appearance of the IL-1-like factor during postnatal development and investigates its cellular origin further. IL-1 activity was measured by a murine thymocyte proliferation assay. Very low IL-1 activity was present in culture medium conditioned by seminiferous tubules from rats aged 10 or 20 days. From 30 days of age, increasing amounts were detected, reaching a maximum level in adult animals (60-90 days). No IL-1 activity was found in medium conditioned by peritubular cells. Sertoli cell-enriched seminiferous tubules obtained from experimentally cryptorchid or from prenatally irradiated rats produced much higher levels of IL-1 activity than did those obtained from intact testes. IL-1 activity was detected in efferent duct fluid after ligation of the efferent ducts for 24 h, indicating that the IL-1-like factor was secreted into the tubular lumen. Low levels of IL-1 activity were detected in extracts of epididymal tissue and epididymal sperm, whereas ejaculated seminal plasma, seminal vesicle fluid and extracts of seminal vesicles (together with the coagulating glands) and ventral and dorsolateral prostate lacked IL-1 activity. Instead, seminal plasma inhibited testicular IL-1 activity dose-dependently without affecting cell viability in the thymocyte cultures. Although its biological function remains to be defined, our results indicate that the testicular IL-1-like factor is produced by Sertoli cells and that its appearance during development coincides with the initiation of active spermatogenesis in the rat testis.     

Obstruction of the tubuli recti and ductuli efferentes by dilated veins in the testes of men with varicocele and its possible role in causing atrophy of the seminiferous tubules

Hormone measurements, spermiograms and testicular biopsies studies were performed in young with varicocele. In addition, the testes and epididymides of 27 adults with varicocele were obtained from autopsies. Light and electron microscopic examination of biopsy and autopsy specimens revealed two types of lesions in testes with varicocele: 1) a diffuse lesion consisting of abnormal spermatozoa and spermatid morphology and sloughing of immature spermatozoa and spermatid; 2) focal lesion, distributed irregularly throughout the testicular parenchyma, affecting several small groups of seminiferous tubules. Each of these groups corresponded to a testicular lobule and showed different degrees of tubular atrophy, so that the focal lesions were distributed in a mosaic pattern. The testicular interstitium showed dilated veins and venules, and progressive collagenization. Some testes showed dilated veins in the rete testis, which compressed several tubuli recti and caused tubular atrophy in the seminiferous tubules opening into these tubuli recti. Other testes showed dilated young veins among the ductuli efferentes, and the rete testis channels appeared to be dilated. Among the different etiological mechanisms which have been suggested to for testicular lesions in varicocele, tubular obstruction at the level of either the tubuli recti or the ductuli efferentes might be responsible for lesions leading to testicular atrophy.     

5-氟脲嘧啶诱发的小鼠睾丸形态学早期变化

目的:通过观察化疗药物5-氟脲嘧啶诱发小鼠睾丸组织形态学早期变化特点,提出一种简易实用的小鼠少精/弱精/无精模型制备方法,为相应生精机制研究和药物疗效观察提供方法学建议。方法:小鼠尾静脉一次性注射化疗药物5-氟脲嘧啶(250mg/kg),分别在注射前,以及注射后第3、7、11、14天取小鼠睾丸,制备石蜡切片,HE染色观察形态学变化。结果:小鼠睾丸内完整致密排列的生精小管管壁中各级精母细胞/精子细胞,在注射5-氟脲嘧啶之后第3、7、11天呈现进行性减少,管壁进行性变薄,在第11天达到最低点,并可见管壁明显肿胀和裂纹;第14天生精小管肿胀基本消失,但裂纹依然存在,可见精母细胞明显增多,但未见成熟精子。结论:小鼠尾静脉一次性注射5-氟脲嘧啶可能是一种简单、有效的化疗药物诱发生殖功能损伤动物模型制备方法。     

口服丙烯酰胺对雄性大鼠生长发育及生殖机能的影响

目的:研究丙烯酰胺对雄性大鼠的生殖毒性作用。方法:30只21日龄断奶未成熟雄性大鼠随机分为3组,实验组Ⅰ和实验组Ⅱ分别通过自由饮水方式口服5 mg/kg.d和10 mg/kg.d的丙烯酰胺溶液8周,对照组饮用自来水。分两批(第4周和第8周时)对体重、脏器重等指标进行检测,并做睾丸和附睾的组织形态学观察;第8周时,同时检查附睾尾精子密度和精子形态。结果:两实验组大鼠体重增加显著低于对照组(P<0.05),至实验8周时,睾丸、附睾性器官发育已受到影响,实验组Ⅱ大鼠附睾尾部精子密度明显低于对照组(P<0.05),实验组Ⅰ与对照组差异不显著(P>0.05)。睾丸出现不同程度的病理变化,发生调亡的生精小管周围间质细胞显著增多(P<0.05)。结论:丙烯酰胺会对生精小管产生毒性作用而导致雄性大鼠精子生成减少。     

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.