Immunocytochemical localization of follicle regulatory-protein (FRP) in testis

Follicle regulatory protein (FRP) can exert paracrine control over follicular development. It is synthesized by the granulosa cells of the developing follicles and was localized in the cytoplasm of the mural cells by immunocytochemistry. When administered to male dogs and rats, FRP causes impairment of spermatogenesis. In the intact male rat, it has been postulated that FRP manifests its effects at a stage prior to the conversion of testosterone to dihydrotestosterone. Sertoli cells of the seminiferous tubules are implicated in testosterone metabolism. Furthermore, Sertoli cells in male gonads are regarded as the counterpart of granulosa cells in ovaries. The exact source of FRP in the male is not known. Therefore, it was of interest to study the localization of FRP in the male gonads. Testicular sections of the pig, dog, cat, rat, mouse, monkey, and man were immunocytochemically stained with monoclonal antibody to porcine FRP of ovarian origin. Sections of pig ovaries were used as controls throughout the study. Specificity of immunocytochemical localization was established by preabsorption. FRP antibody predominantly localized to the interstitial compartment of the pig testis. In the seminiferous tubules, FRP localization was limited to basal spermatogonia and Sertoli cells of tubules at few specific stages of spermatogenesis. The study also showed that the monoclonal antibody against porcine FRP is species-specific. Antibody binding was found only in pig testis, whereas tissues from the cat, dog, mouse, rat, monkey, and man did not display any immunocytochemical reaction. Since in the pig testis, Sertoli cells at specific stages of spermatogenesis showed FRP localization, it would appear that FRP production is not being carried out by Sertoli cells at other stages. Due to the fact that all of the interstitial cells stained with FRP and some of the Sertoli cells were stained with FRP-antibody, it is not possible to ascertain the exact cell type responsible for FRP synthesis and secretion in testis using immunocytochemistry. Since the antibody to FRP of ovarian follicular fluid origin bound to various testicular cells, it would appear that FRP or a protein of similar nature may also be present in the testes.     

Immunocytochemical localization of follicle regulatory-protein (FRP) in testis.

Follicle regulatory protein (FRP) can exert paracrine control over follicular development. It is synthesized by the granulosa cells of the developing follicles and was localized in the cytoplasm of the mural cells by immunocytochemistry. When administered to male dogs and rats, FRP causes impairment of spermatogenesis. In the intact male rat, it has been postulated that FRP manifests its effects at a stage prior to the conversion of testosterone to dihydrotestosterone. Sertoli cells of the seminiferous tubules are implicated in testosterone metabolism. Furthermore, Sertoli cells in male gonads are regarded as the counterpart of granulosa cells in ovaries. The exact source of FRP in the male is not known. Therefore, it was of interest to study the localization of FRP in the male gonads. Testicular sections of the pig, dog, cat, rat, mouse, monkey, and man were immunocytochemically stained with monoclonal antibody to porcine FRP of ovarian origin. Sections of pig ovaries were used as controls throughout the study. Specificity of immunocytochemical localization was established by preabsorption. FRP antibody predominantly localized to the interstitial compartment of the pig testis. In the seminiferous tubules, FRP localization was limited to basal spermatogonia and Sertoli cells of tubules at few specific stages of spermatogenesis. The study also showed that the monoclonal antibody against porcine FRP is species-specific. Antibody binding was found only in pig testis, whereas tissues from the cat, dog, mouse, rat, monkey, and man did not display any immunocytochemical reaction.(ABSTRACT TRUNCATED AT 250 WORDS)     

Prevention of development of post-traumatic atrophy of the rat testis by injection of aspirin

The left testis was punctured with a needle (diameter 3 mm) in 42 sexually mature Wistar rats. The development of atrophy of the testis was observed 12 days after the operation in control animals receiving “empty” suppositories: the weight of the injured organ was greatly reduced, the seminiferous tubules of the whole testis were empty, their spermatogenic epithelium had undergone degeneration or destruction, the permeability of the blood-testicular barrier (BTB) for endogenous globulins was increased, and sharp changes were found in the ultrafine structure of the principle components of the barrier — the tunica propria of the seminiferous tubules and the Sertoli cells. After injection of aspirin (0.5 g daily for 5 to 12 days) into the rats the development of post-traumatic atrophy of the testes was not observed. The aspirin had no effect on the character and intensity of pathological processes developing in the focus of injury, but it prevented the spread of destructive changes to the intact part of the testis and disturbance of the permeability of the BTB away from the region of injury. The effect of aspirin on the development of post-traumatic testicular atrophy is evidently connected with its inhibitory action on prostaglandin synthesis.     

孕期非那雄胺暴露致子代雄性小鼠生殖器官发育异常

目的:探讨孕期非那雄胺暴露对子代雄性小鼠生殖器官发育的影响。方法:CD-1小鼠在受孕后0~17 d给予非那雄胺处理,通过宏观观察、解剖分析与组织形态学染色观察子代雄性小鼠生殖器官的发育情况;通过免疫荧光染色分析子代雄性小鼠精子发生情况。结果:宏观观察结果显示,孕期非那雄胺暴露可导致子代雄性小鼠外生殖器官畸形,表现为阴囊未完全融合及阴茎畸形;此外,还观察到小鼠肛门与生殖器的距离显著缩短(P<0.01)。解剖分析结果显示,孕期非那雄胺暴露可导致子代雄性小鼠睾丸不同程度的不完全下降及长度显著缩短(P<0.01)。组织形态学结果显示,各阶段阴茎长度均显著缩短(P<0.01);睾丸生精小管密度和生精小管管腔成熟精子数均显著降低(P<0.01),生精小管管腔和睾丸间质间隙均显著增大(P<0.01)。免疫荧光染色结果显示,睾丸中支持细胞、睾丸间质细胞和精原细胞的密度均显著降低(P<0.01);生精小管细胞的caspase-3荧光强度显著增加(P<0.01),Ki67与沙漠刺猬因子(desert hedgehog,Dhh)荧光强度均显著降低(P<0.01)。结论:孕期非那雄胺暴露可导致子代小鼠生殖器官发育异常并影响精子发生。     

Reinitiation of spermatogenesis by exogenous gonadotropins in a seasonal breeder,the woodchuck (Marmota monax), during gonadal inactivity

The present study was undertaken (1) to document structural and functional changes in the testes of seasonally breeding woodchuck during active and inactive states of spermatogenesis and (2) to evaluate the ability of exogenous gonadotropins to reinitiate spermatogenesis outside the breeding season. During seasonal gonadal inactivity, there were significant (P < 0.05) reductions in volumes of several testicular features (testis, seminiferous tubules, tubular lumen, interstitial tissue, individual Leydig cells, Leydig cell nuclei, and Leydig cell cytoplasm) as compared with gonadally active animals. The diameter of the seminiferous tubules was decreased by 26%, and Leydig cell numbers also declined in the regressed testes. These changes were accompanied by a decline in testosterone (T) levels in both plasma and testis, and reduction in epithelial height of accessory reproductive organs. A hormonal regimen was developed that would reinitiate spermatogenesis in captive, sexually quiescent woodchucks. A combination of PMSG and hCG markedly stimulated testicular growth and function and restored spermatogenesis qualitatively. Quantitatively normal spermatogenesis was restored in 2 of 6 treated males. Morphometric analyses revealed substantial increases in seminiferous tubular diameter and in the volume of seminiferous tubules, tubular lumen, total Levdig cells, and individual Leydig cells in the hormone-treated animals. These increased values corresponded to 99, 75, 68, 51, and 200%, respectively, of the values measured in naturally active woodchucks. Leydig cell numbers, however, remained unchanged and approximated only 31% of the number found in naturally active testes. Hormonal stimulation also resulted in a significant rise in serum T as well as in the total content of testicular T, and a marked increase in epithelial height in various accessory reproductive glands. The most effective hormonal protocol for stimulating spermatogenesis was treatment with 12.5 IU of PMSG twice a week for 4 weeks followed by 12.5 IU of PMSG + 25 IU of hCG twice a week for 4 weeks.     

细辛对D-半乳糖所致衰老小鼠睾丸的形态学研究

本文研究了细辛对D－半乳糖所致衰老小鼠的抗衰老作用，应用光镜电镜技术测定小鼠睾丸的重量、生精小管直径、生精上皮细胞数、随龄变化的间质细胞数，同时观察了细辛对上述指标的影响。结果 1．随增龄、睾丸重量减轻，生精小管直径缩小。衰老时租精细胞缺如，仅有支持细胞或散在分布，间质细胞随龄递减。2．细辛可以使小鼠的曲细精管增粗，生精过程活跃，生精细胞增多，间质细胞增多。结论 细辛有一定抗衰老作用。     

Immunohistochemical analysis of the vimentin filaments in Sertoli cells is a powerful tool for the prediction of spermatogenic dysfunction

The close interaction between male germ cells and Sertoli cells, a type of somatic cell found in the seminiferous tubules of mammalian testis, is essential for the normal progression of spermatogenesis in mammals. Vimentin is an intermediate filament protein that primarily provides mechanical support, preserves cell shape, and maintains the nuclear position, and it is often used as a marker to identify Sertoli cells. Vimentin is known to be involved in many diseases and aging processes; however, how vimentin is related to spermatogenic dysfunction and the associated functional changes is still unclear. In a previous study, we reported that vitamin E deficiency affected the testes, epididymis, and spermatozoa of mice, accelerating the progression of senescence. In this study, we focused on the Sertoli cell marker vimentin and explored the relationship between the cytoskeletal system of Sertoli cells and spermatogenic dysfunction using testis tissue sections that caused male reproductive dysfunction with vitamin E deficiency. The immunohistochemical analysis showed that the proportion of the vimentin-positive area in seminiferous tubule cross-sections was significantly increased in testis tissue sections of the vitamin E-deficient group compared with the proportion in the control group. The histological analysis of testis tissue sections from the vitamin E-deficient group showed that vimentin-positive Sertoli cells were greatly extended from the basement membrane, along with an increased abundance of vimentin. These findings suggest that vimentin may be a potential indicator for detecting spermatogenic dysfunction.     

Renal receptors evoking a spinal vasometer reflex

1. A permeability barrier in or around the seminiferous tubules of rams has been demonstrated by studying the rate of passage of a variety of substances from blood plasma into fluid collected from the rete testis and into testicular lymph.2. All substances studied passed readily into testicular lymph.3. Tritiated water, urea, ethanol and bicarbonate in rete testis fluid equilibrated with blood plasma within 3 hr; Na(+), K(+), Rb(+), Cl(-), I(-), CNS(-), creatinine and galactose entered slowly and p-aminohippurate (PAH), glutamate, iodinated albumin, inulin and [(51)Cr]EDTA did not appear in rete testis fluid at all.4. Rubidium was excluded relative to iodoantipyrine from the testes of control and hypophysectomized rats and from rat testes heated to 37, 40, 43 and 45 degrees C; no such exclusion was seen in testes of rats which had been given cadmium chloride 5 months earlier so as to destroy the seminiferous tubules.5. It is suggested that this permeability barrier will regulate the access to the seminiferous epithelium of some constituents of blood plasma, isolate the germinal cells immunologically and help to maintain the concentration differences between rete testis fluid and lymph or blood plasma.     

Immunohistochemical analysis of connexin43 expression in infertile human testes

Connexin43 (Cx43) is abundantly expressed in mammalian testes and implicated in the regulation of cell-to-cell interaction between germ cells and Sertoli cells, which is essential to the normal process of spermatogenesis. In the present study, we investigated the relation between Cx43 expression and the degree of spermatogenesis in infertile human testes. Immunohistochemical analysis of Cx43 was performed on testicular biopsies from 29 patients with azoospermia (n=23) and severe oligospermia (n=6), who gave informed consent to this experiment. The degree of testicular spermatogenesis was evaluated by Johnsen score. In the interstitium, immunostaining for Cx43 was localized to some focal parts of plasma membrane between neighboring Leydig cells. In seminiferous tubules with normal spermatogenesis, Cx43 expression was found between Sertoli cells and germ cells. However, Cx43 expression in maturation arrest was decreased and located mainly in the basal compartment of seminiferous tubules. Finally, there was a significant positive correlation between histological score of spermatogenesis and intensity of Cx43 (p=0.0294). These data suggest that the alteration of Cx43 expression may be involved in spermatogenic impairment, and that the communication between Sertoli cells and germ cells through Cx43 may be important for maturation of spermatogenesis.     

Immunohistochemical study of flotillin-1 in the rat testis during postnatal development

The level and cellular localization of fotillin-1, a lipid raft protein, was examined in the testis of rats during postnatal development and spermatogenesis in order to determine if flotillin-1 is involved in testicular development. The testes of rats were sampled on postnatal days 7, 14, 21, 40, and 60, and analyzed by Western blot and immunohistochemistry. Western blot analysis detected flotillin-1 in the testes at days 7 and 14 after birth but the level decreased significantly at postnatal days 21, 40 and 60. At postnatal days 7, 14, 21, and 40, flotillin-1 immunolocalization was observed mainly in the Sertoli cells. However, there was little flotillin-1 immunolabeling in the spermatogenic cells from the seminiferous tubule of the testes. In the seminiferous tubule of the testes at postnatal day 60, flotillin-1 immunoreactivity in the Sertoli cells varied according to the stages of the spermatogenic cycle; intense immunoreactivity being observed in stages IX–III and less in stages IV–VIII. These results suggest that flotillin-1 participates in the developmental process of Sertoli cells and is involved in the regulation of spermatogenesis.     

Autoimmune nature of the disturbance of spermatogenesis in rats with experimental varicocele

Measured disturbance of the venous outflow from the left testis in rats causes the development of destructive changes in the spermatogenic epithelium both in the testis on the side of the operation and also in the contralateral organ. Disturbances of spermatogenesis in rat testes (foci of desquamation of spermatogenic epithelium, disorganization and degeneration of the sex cells, emptying of the seminiferous tubules) are similar to those in men with varicocele, so that the results of such experiments can be regarded as an experimental model of varicocele. In the experimental rats the permeability and fine structure of the blood-testis barrier were disturbed in both testes, the pattern of the morphological changes was similar with that observed during the development of autoimmune orchitis, and lymphocytes sensitized to spermatozoal antigens were found in the lymphoid organs. Taken as a whole, the results suggest involvement of immunologic mechanisms in the development of the pathological changes in the testes in varicocele.Laboratory of Human Embryonic Histogenesis, Institute of Human Morphology, Academy of Medical Sciences of the USSR. Department of Pediatric Surgery, N. I. Pirogov Second Moscow Medical Institute. (Presented by Academician of the Academy of Medical Sciences of the USSR A. P. Avtsyn.) Translated from Byulleten' Éksperimental'noi Biologii i Meditsiny, Vol. 87, No. 1, pp. 44–48, January, 1979.     

Germ cell transfer into rat, bovine, monkey and human testes.

Germ cell transplantation is a potentially valuable technique offering oncological patients gonadal protection by reinitiating spermatogenesis from stem cells which were reinfused into the seminiferous tubules. In order to achieve an intratubular germ cell transfer, intratubular microinjection, efferent duct injections and rete testis injections were applied on dissected testes of four different species: rat, bull, monkey and man. Ultrasound-guided intratesticular rete testis injection was the best and least invasive injection technique with maximal infusion efficiency for larger testes. Deep infiltration of seminiferous tubules was only achieved in immature or partially regressed testes. This technique was applied in vivo on two cynomolgus monkeys. In the first monkey a deep infusion of injected cells and dye into the lumen of the seminiferous tubules was achieved. In the second, transplanted germ cells were present in the seminiferous epithelium 4 weeks after the transfer. These cells were morphologically identified as B-spermatogonia and located at the base of the seminiferous epithelium. In summary, this paper describes a promising approach for germ cell infusion into large testes. The application of this technique is the first successful attempt of a germ cell transfer in a primate.     

Testicular development in cynomolgus monkeys

The testes from 136 male cynomolgus monkeys were examined histopathologically in order to investigate the relationship between the development of spermatogenesis and testis weight, age, and body weight. At Grade 1 (immature), Sertoli cells and spermatogonia were the only cell classes in the testis. At Grade 2 (pre-puberty), no elongated spermatids were observed in the testis, although a few round spermatids and small lumen formation were observed. At Grade 3 (onset of puberty), all classes of germ cells were observed in the testis, although seminiferous tubule diameters and numbers of germ cells were small. Slight debris in the epididymis was observed in almost all animals. At Grade 4 (puberty), almost complete spermatogenesis was observed in the seminiferous tubules and it was possible to ascertain the spermatogenesis stage as described by Clermont, although tubule diameters and numbers of germ cells were small. There was less debris in the epididymis than at Grade 3. At Grade 5 (early adult), complete spermatogenesis was observed in the seminiferous tubules. At Grade 6 (adult), complete spermatogenesis in the seminiferous tubules and a moderate or large number of sperm in the epididymis were observed. Moreover, sperm analysis using ejaculated sperm was possible. Logistic regression analysis showed that testis weight is a good indicator of testicular maturity.     

Experimental allergic orchitis in mice

Summary Experimental allergic orchids was induced in (C57BL/6J × A/J)F₁ mice by two injections of syngeneic testicular homogenate emulsified with adjuvants immediately followed by intravenous injection of pertussis vaccine, at a 2 week interval.Histologically, in the initial stage there was occasional focal degeneration and desquamation of both spermatogonia and Sertoli cells within limited parts of the seminiferous tubules, in the peripheral region of the testis. No inflammatory change was present. In some cases, however, inflammatory reaction in the rete testis and focal lymphocytic infiltration in the interstitium were also observed. Subsequently, marked infiltration of lymphocytes, monocytes, and polymorphs were found not only in the testes, but also in rete testis and epididymis. In later stages the inflammatory reaction gradually subsided, but the testes became atrophic due to progression of spermatogenic arrest. Many tubules were lined only with monolayers of Sertoli cells, surrounded by hyperplastic Leydig cells in the interstitium. At 5 months after the 2nd immunization, there was still variable depression of spermatogenesis and hyperplasia of Leydig cells with scattered fibrous scars in the seminiferous tubules, although good regeneration of germ cells appeared in some tubules.Immunological studies revealed that lymphocytes obtained from mice bearing developed orchitis showed a significantly enhanced response in the mixed culture with syngeneic testicular cells, and suggest that cellular immunity plays an important role in the induction of experimental allergic orchitis in mice.     

Reticulin fibres in the tunica albuginea and peritubular tissue of seminiferous tubules of adult male Wistar rats

Reticulin fibres are fine fibres that contain primarily collagen type III and are found in soft blood-forming or blood-processing tissues, and are supportive elements in kidney, liver and thymus. This study demonstrates for the first time the presence of reticulin fibres in the tunica albuginea and peritubular tissue of seminiferous tubules of adult rat testes after staining with the metallic silver impregnation method. Reticulin fibres of peritubular tissues may provide a supportive framework for germinal epithelium of seminiferous tubules to allow the periphery-to-centre progression of spermatozoa during spermatogenesis. The presence of fibres in all stages of the spermatogenic cycle suggests that they have structural functions.     

Three‐dimensional structure of seminiferous tubules in the adult mouse

Seminiferous tubules develop from sex cords, which are embryonic structures with simple C‐shaped arches. Histologically, the epithelium of adult mouse seminiferous tubules has been divided into 12 stages based on the associations of spermatogenic cells in four cycles of spermatogenesis. However, the gross characteristics of the seminiferous tubules themselves, including their number, length, run, and mutual relationships remain largely unknown. In the present study, we analyzed all seminiferous tubules in a single adult mouse testis with high resolution using serial paraffin sections and high‐perfomance three‐dimensional reconstruction software. There were 11 seminiferous tubules with an average length of 140 mm. Each tubule ran along circular paths within the testis while making convolutions with cranial and caudal hairpin turns. The cranial turns of all tubules were in contact with the tunica albuginea, whereas the caudal turns were not, resulting in funnel‐shaped networks of these tubules with tapered caudal portions. The caudally located networks surrounded the preceding cranially located networks from the bottom and outside, similar to stacked paper cups. Five out of the 11 seminiferous tubules were continuous from one end to the other both connected with the rete testis (10 connection points). Nine branching points, one blind end, and 18 more connection points with the rete testis were detected in the remaining six seminiferous tubules, making the paths of these tubules complicated to various degrees. The present study revealed that the 3D structures of seminiferous tubules were highly regular as a whole in the adult mouse testis.     

不同阶段生精小管组织学结构研究

目的探讨不同阶段人体睾丸生精小管面积、生精小管管腔面积变化和生精上皮在不同阶段的组织学特点,及其与生殖的关系。方法:应用常规组织制片技术和图像分析技术。结果①生精小管平均面积变化,从胚胎睾丸形成到青春期前,随睾丸逐渐发育增大,睾丸间质增多,但生精小管面积无明显增大;自青春期生精小管面积迅速增大,25岁左右达到峰值,45岁左右生精小管平均面积缓慢减少,55岁以后显著减少。②生精小管管腔面积变化,从胚胎睾丸形成到青春期前,生精小管几乎无管腔;青春期管腔开始出现并迅速增大,20岁左右达到峰值;于45岁左右管腔面积缓慢减少,55岁以后显著减少。③生精小管的组织学结构变化,从胚胎睾丸形成到青春期前,生精小管上皮由精原细胞和支持细胞组成,但随睾丸发育增大,睾丸间质增多,生精小管上皮和基膜间渐出现明显的间隙;青春期开始,生精小管上皮发育,生精细胞层数增加,管壁各级生精细胞典型,腔面可见精子;55岁后睾丸纤维化明显,生精小管皱缩,随年龄增长,生精上皮细胞数量渐减少,排列紊乱,基膜增厚。结论①生精细胞增殖旺盛是生精小管平均面积迅速增大的原因之一;生精细胞增殖旺盛的阶段是20～30岁,最佳时期是25岁左右。②生精小管管腔的出现与生精细胞的凋亡、基膜扩大的速率远远大于生精细胞的增殖水平有关,而生精小管管腔的出现有利于精子的生成与运输。③衰老睾丸生殖功能的下降与其组织结构的纤维化及生精小管基膜厚度增加等因素有关。     

Morphological alterations and distribution of occludin in rat testes after bilateral vasectomy

The aim of study was to investigate the fate and the morphology of the cells which constitute the spermatogenic line, and to determine the distribution of occludin in the testis in adult vasectomized Wistar rats. The rats were divided into two groups: control group (sham-operated) and vasectomized group. One, 3 and 6 months after sham and vasectomy operations, testis samples were examined. The weight of the testes was found to be reduced 3 and 6 months after vasectomy. There was vacuolization in the seminiferous tubules one month after vasectomy. The tubules showed severe atrophy 3 and 6 months after vasectomy. The occludin immunolabeling in the 3- and 6-month groups was weak and diffuse, and the density of the protein was found to be decreased. The increase in the number of apoptotic cells was accompanied by a time-dependent decrease in the number of haploid, diploid and tetraploid cells. This study demonstrated that vasectomy causes degeneration in the seminiferous tubules with alterations in occludin distribution with a decrease in the number of spermatogenic cells. Moreover, these alterations increase in a time-dependent manner.     

The role of angiotensin-(1–7) receptor Mas in spermatogenesis in mice and rats

Evidence regarding the components of the renin–angiotensin (Ang) system suggests that this system plays an important role in male reproduction. However, there are few data available in the literature on the effects of Ang-(1–7) on the male reproductive system. The present study investigated the effects of the genetic deletion and chronic blockage of Ang-(1–7) receptor Mas on spermatogenesis and male fertility. The localization of Mas in mouse and rat testes was determined by binding assays and immunofluorescence, whereas the testis structure and spermatogenic process were morphologically and stereologically analysed by light microscopy. Ang-(1–7) binding and immunofluorescence revealed the presence of Mas in the testes of mice and rats. Although the total numbers of Sertoli and Leydig cells per testis and Leydig cell size were similar in both wild-type and Mas -deficient mice, Mas ^−/– animals exhibited a significant reduction in testis weight and a greater volume of apoptotic cells, giant cells and vacuoles in the seminiferous epithelium. In both mice and rats, an increased number of apoptotic cells were found during meiosis. Due to disturbed spermatogenesis, daily sperm production was markedly reduced in Mas ^−/– mice. Moreover, chronic infusion of A-779 [an Ang-(1–7) antagonist] in rats significantly increased the total number of apoptotic cells and primary spermatocytes in particular stages of spermatogenesis. Taken together, these findings strongly suggest that Ang-(1–7) receptor Mas plays an important role in the regulation of spermatogenesis.     

杜仲对D-半乳糖所致衰老小鼠睾丸的形态学研究

目的 本实验以D－半乳糖所致衰老小鼠为研究对象，研究了杜仲的抗衰老作用。方法 应用光镜电镜技术观察小鼠睾丸的重量、生精小管直径、生精上皮细胞数、间质细胞数的随龄变化，同时观察了杜仲对上述指标的影响。结果 1、随增龄，睾丸重量减轻，生精小管直径缩小。衰老时生精细胞缺如，仅剩支持细胞或见散在分布，间质细胞随龄递减。2、杜仲具有一定的抗衰老作用，使生精过程活跃，生精细胞增多，间质细胞增多不明显，生精小管直径改变不显著。结论 杜仲具有一定的抗衰老作用。