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1.
Imbalances in the proliferation and apoptosis processes are involved in numerous epithelial alterations. In the seminiferous epithelium, normal spermatogenesis is regulated by spermatogonia proliferation and germ cell apoptosis, and both processes are involved in diverse pathological alterations of the seminiferous epithelium. Other physiological phenomena including aging and short photoperiod, in which apoptosis and proliferation seem to play important roles, cause testicular changes. Aging is accompanied by diminished proliferation and increased apoptosis, the latter occurring in specific states of the seminiferous cycle and considered the cause of epithelium involution. However, there is no clear evidence concerning whether proliferation decreases in the spermatogonia themselves or is due to an alteration in the cell microenvironment that surrounds them. As regards the factors that regulate the process, the data are scant, but it is considered that the diminution of c‐kit expression in the spermatagonia, together with the diminution in antiapoptotic factors (Bcl‐xL)) of the intrinsic molecular pathway of apoptosis play a part in epithelial regression. A short photoperiod, especially in rodents, produces a gradual involution of the seminiferous epithelium, which is related with increased apoptosis during the regression phase and a diminution of apoptosis during recrudescence. Proliferative activity varies, especially during the total regression phase, when it usually increases in the undifferentiated spermatogonia. In other species showing seasonal reproduction, however, decreased proliferation is considered the main factor in the regression of the seminiferous epithelium. Little is known about how both phenomena are regulated, although data in rodents suggest that both the intrinsic and extrinsic pathways of apoptosis contribute to the increase in this process. In conclusion, regression of the seminiferous epithelium in physiological situations, as in many pathological situations, is a result of alterations in equilibrium between the proliferation and apoptosis of germinal cell types. However, both physiological phenomena showed important differences as regard proliferation/apoptosis and their regulation pathways, probably as a result of their irreversible or reversible character.  相似文献   

2.
A morphometric study was conducted on the testis of the domestic quail Coturnix coturnix japonica to determine testicular kinetics. We investigated the variability along the year of testicular parameters such as seminiferous tubule diameter, germinal epithelium height and amount of meiotic figures of maturing spermatids in the seminiferous epithelium and of sperm in the tubular lumen. The results of morphometric analysis showed the occurrence of an annual testicular cycle defined by four distinct phases: a resting phase (at the end of summer), a recrudescence phase (in the fall), a proliferative phase (at the end of winter and beginning of spring), and a regression phase (spring and summer). We also observed that the testes of adult quails present elevated and maximal spermatogenic activity in fall-winter (short-day period) and at the beginning of spring, respectively, and lower values in spring and summer (long-day periods), with minimum values at the end of summer.  相似文献   

3.
Quantitative analysis of testis structure was performed during early post-natal development in Wistar rats. For this purpose, at 1, 7, 14, 21, 28, 35, 42, 60 and 90 days after birth, weights and volumes of testes were recorded and fixed in Bouin's solution. For stereological studies, 5-μm paraffin sections were stained with haematoxylin-eosin. Relative and then absolute volumes of seminiferous tubules, germinal epithelium, seminiferous tubuli lumina and interstitial tissue were estimated by point-counting method. The results showed that weight and volume of testis in rats increase 75- and 86.28-fold during post-natal development, respectively. The greatest growth rate (2.96-fold) of testis was observed between days 35 and 42. Also, diameter of seminiferous tubules increased significantly (P<0.001) between different ages and represented 5.55-fold increase during post-natal development. The percentage volume of tubular tissue increased 1.4-fold between birth and 90 days of age. Interstitial tissue formed 36.68±0.90% of testicular parenchyma at birth. This percentage decreased progressively during post-natal development until 90 (9.00±0.55%) days of age. Lumen of seminiferous tubules was recognized at day 28, and its relative volume increased with age. This study provides systematic data on the stereological characteristics of developing Wistar rat testis.  相似文献   

4.
The object of this study was to determine the details of morphological dynamics of spermatogenesis in Syrian hamsters exposed to both short photoperiod and low ambient temperature. Eight-week-old male hamsters, kept in a long photoperiod (14 h L, 10 h D), were transferred to a short photoperiod (6 h L, 18 h D) and kept there for 13 weeks to induce testicular regression. Some hamsters were then transferred from the room at 23 degrees C to that at 5 degrees C (5 degrees C group). Remaining hamsters were continuously kept at 23 degrees C (23 degrees C group). Thereafter, the morphology was examined. As a result, it took only 8 weeks until spermatogenesis recovered in the 23 degrees C group. However, it was not until 20 weeks that spermatogenesis was recognized in the 5 degrees C group. As the regulation of seasonal testicular activity is characterized by coordinated shifts in the relationships among mitosis, meiosis, and apoptosis, the changes in the proliferative and apoptotic activities were examined. Although no significant difference in proliferative activity of spermatogonia between the 5 degrees C and the 23 degrees C groups was confirmed, a notable increase in the rate of apoptosis was observed in the 5 degrees C group. Furthermore, this increase was more salient during the hibernation period. These findings suggest that both cold ambient temperature and hibernation caused the delay of testicular recrudescence and this delay arose from the increase of apoptotic activity but not the change in proliferative activity in spermatogonia in the 5 degrees C group.  相似文献   

5.
The position and histological structure of the testes of 33 brown hares (Lepus europaeus) were studied from July to December. From July to September, the testes were located in the scrotum; in October and November, in some animals, the testes were positioned more or less in the inguinal canal towards the abdominal cavity, and in December none of the investigated animals had testes located in the scrotum. Testes were weighed and a quantitative analysis of tissue components was performed: the diameter of the seminiferous tubules, the depth of the seminiferous epithelium, the thickness of the tunica albuginea, the thickness of the peritubular tissue and the relative proportion of seminiferous tubules were determined. The tunica albuginea and peritubular tissue were thickest in September, October and at the beginning of November. In the same months the testis weight was low, and the diameter of the seminiferous tubules, the depth of the seminiferous epithelium and the relative proportion of seminiferous tubules in the testis tissue were significantly lower than in other months. We did not find any correlation between testicular regression or testis weight reduction and the change in the position of the testes. During recrudescence of spermatogenesis in November and December the testes were located in the inguinal canal.  相似文献   

6.
Five Syrian hamsters were exposed to a short photoperiod (8L:16D) during 159 days. Atrophied testes were removed, fixed in Allen's solution; paraffin sections of the testicular tissues and whole-mounted seminiferous tubules were prepared. The numbers of various types of spermatogonia were investigated and compared with those in animals maintained in natural photoperiod (12L:12D). All the types of differentiated spermatogonia (A1, A2, In, B1, B2) were significantly decreased in number after the treatment of short photoperiod exposure, while undifferentiated spermatogonia (isolated, paired and aligned type) were significantly increased at stages V-VI and VII-VIII of the seminiferous epithelial cycle. This strictly local reaction of the undifferentiated spermatogonia to the loss of the differentiated spermatogonia suggests the presence of a feedback effect of a certain type(s) of differentiated cells to the undifferentiated spermatogonial proliferation. This feedback mechanism may also play an important role for regulating annual changes in spermatogenesis of seasonal breeders, not only in laboratory but also in natural habitat.  相似文献   

7.
The postnatal testicular development and actin distribution in the seminiferous epithelium were examined by light microscopy, using the testes of the Habu (Trimeresurus flavoviridis; snake) from 0-year-old to 3-year-old. At 0-year-old (about 1 month after birth), the testis was quite small in size, and the seminiferous epithelium was composed of only Sertoli cells and large spermatogonia. Actin immunoreactivity was observed in the peritubular myoid cells, but could not be detected in the seminiferous epithelium. At 1-year-old (about 10 months after birth), the testicular size increased to a great degree. In the seminiferous epithelium, spermatocytes newly appeared. Actin could still not be detected in the seminiferous epithelium. At 2-year-old (about 1 year and 10 months after birth), the testes continued to develop in size. In the seminiferous epithelium, elongate spermatids and round spermatids were frequently seen, in addition to Sertoli cells, spermatogonia and spermatocytes. Thus, active spermatogenesis was clearly recognized at this age. Moreover, the actin distribution in the seminiferous epithelium was observed at the site between Sertoli cells and spermatids, as well as that at adult stage. The immunoreactivity of actin in the peritubular myoid cells gradually increased from 0-year-old to 2-year-old. Conclusively, it seems likely that spermatogenesis in the Habu initiates at 2-year-old, accompanying with the appearance of actin in the seminiferous epithelium.  相似文献   

8.
The testicular interstitium of Syrian hamster (Mesocricetus auratus) was studied during ageing and in testicular regression after exposure to a short photoperiod, in relation to the interstitial cells and their connective tissue. This tissue was assessed histochemically using Masson's trichrome technique and the expression of Heat Shock Protein 47 (HSP‐47) and collagen IV (α5) was assessed in Leydig cells. Finally, an ultrastructural analysis of some cells of the testicular interstitium was made. Leydig cells were positive for HSP‐47 and collagen IV (α5). Ageing did not change the parameters studied while the short photoperiod altered the synthetic activity of Leydig cells. The positivity index of these cells for HSP‐47 was significantly higher in the regressed testis, but was lower for collagen IV (α5). During ageing no change were observed. Ultrastructural Leydig cells showed a discontinuous basal lamina that did not change during ageing. The basal lamina was not identified in Leydig cells regressed by exposure to a short photoperiod. In conclusion; the intertubular connective tissue suffers little change with age. By contrast, in the testis regressed after exposure to a short photoperiod the studied parameters related to the intertubular connective tissue were altered. These changes are probably related with the low synthetic activity of regressed Leydig cell.  相似文献   

9.
Lectins have been widely used to study the pattern of cellular glycoconjugates in numerous species. In the process of cellular apoptosis, it has been observed that changes occur in the membrane sugar sequences of these apoptotic cells. The aim of our work was to identify which lectins, out of an extensive battery of the same (PNA, SBA, HPA, LTA, Con‐A, UEA‐I, WGA, DBA, MAA, GNA, AAA, SNA), show affinity for germinal cells in apoptosis, at what stage of cell death they do so and in which germinal cell types they can be detected. For this, we studied testis sections during testicular regression in Syrian hamster (Mesocricetus auratus) subjected to short photoperiod. Several lectins showed an affinity for the glycoconjugate residues of germ cells in apoptosis: Gal β1,3‐GalNAcα1, α‐d ‐mannose, N‐acetylgalactosamine and l ‐fucose. Furthermore, lectin specificity was observed for some specific germinal cells and in certain stages of apoptosis. It was also observed that one of these lectins (PNA) showed affinity for Sertoli cells undergoing apoptosis. Therefore, we conclude that the use of lectin histochemistry could be a very useful tool for studying apoptosis in the seminiferous epithelium because of the specificity shown towards germinal cells in pathological or experimentally induced epithelial depletion models.  相似文献   

10.
Chinese Erhualian boars have dramatically smaller testes, greater concentrations of circulating androgens, and fewer Sertoli cells than Western commercial breeds. To identify QTL for boar reproductive traits, testicular weight, epididymal weight, seminiferous tubular diameter at 90 and 300 d, and serum testosterone concentration at 300 d were measured in 347 F(2) boars from a White Duroc x Chinese Erhualian cross. A whole genome scan was performed with 183 microsatellites covering 19 porcine chromosomes. A total of 16 QTL were identified on 9 chromosomes, including 1% genome-wide significant QTL for testicular weight at 90 and 300 d and seminiferous tubular diameter at 90 d on SSCX, and for epididymal weight and testosterone concentration at 300 d on SSC7. Two 5% genome-wide significant QTL were detected for testicular weight at 300 d on SSC1 and seminiferous tubular diameter at 300 d on SSC16. Nine suggestive QTL were found on SSC1, 2, 3, 5, 7, 13, and 14. Chinese Erhualian alleles were not systematically favorable for greater reproductive performance. This study confirmed the previous significant QTL for testicular weight on SSCX and for epididymal weight on SSC7, and reported QTL for seminiferous tubular diameter and testosterone concentration at the first time. The observed different QTL for the same trait at different ages reflect the involvement of distinct genes in the development of male reproductive traits.  相似文献   

11.
This study aimed to assess the biometrics of the testes and the morphology of the seminiferous tubules of Crioulo horses. We studied 10 sexually mature stallions (3–6 years of age). After orchiectomy, testes were perfused with Karnovsky's solution and then embedded in glycol methacrylate. Testis sections (4 μm) were cut and stained with toluidine blue and a solution of 1% sodium borate. The histological images were digitized, and the morphometric analysis was performed using ImageJ software. The average weight of the stallions was 377.5 kg, and the average weight of both testicles was 162.9 g. The percentage of testicular parenchyma occupied by the seminiferous tubules and the intertubular tissue was 77.97% ± 6.34% and 22.03% ± 6.34%, respectively. The average tubular diameter was 205.00 ± 36.91 μm, whereas the average height of the seminiferous epithelium was 70.56 ± 2.82 μm. Average tubular length per testicle and average tubular length per gram of testicle were 4,085.10 ± 1,170.68 m and 26.09 ± 10.63 m/g, respectively. The characteristics of the eight stages of the seminiferous epithelium cycle were similar to those reported in other horse breeds. We conclude that the morphometry of the seminiferous tubules of Crioulo horse resembles what has been reported in other horse breeds. The volumetric proportion of the seminiferous tubules and the Leydig cells of the Crioulo horse is one of the highest ever reported for stallions.  相似文献   

12.
The diameter and area of the seminiferous tubules and the thickness of the germinal epithelium was measured in testes removed from clinically normal dogs of different breeds and mixed ages over a 24 month period which were presented for elective castration or euthanasia. Peripheral plasma testosterone concentrations were determined at the same time. There was no effect of the season of the year on the tubular diameter, thickness of germinal epithelium or tubular area. There was evidence of an effect of age upon tubular diameter and thickness of the germinal epithelium. Peripheral plasma testosterone concentrations were significantly higher in summer and autumn than in winter and spring, but age appeared to have no effect.  相似文献   

13.
The purpose of this study was to analyze the distribution and expression of peptidergic neurotransmitters protein gene product 9.5 (PGP9.5) and neuropeptide Y (NPY) in cryptorchidism and testicular tumors of dogs,compare them with normal testicular tissues of the same age,and provide reference for clinical diagnosis of malignant transformation in testicular tumors of dogs.HE staing,Masson trichrome staining,Gomori silver staining and toluidine blue staining were used to observe the tissue characteristics of reticular fibers,collagen fibers and mast cells.Immunohistochemical SP method and immunofluorescence combined with IPP were used to analyze the expression and localization of PGP9.5 and NPY in tissues.The results showed that the seminiferous epithelium of normal dog testis was composed of 4-7 layers of spermatogenic cells and Sertoli cells,and the distribution of collagen fibers and reticular fibers in interstitial tissue was sparse.The thickness of collagen fibers in the basement membrane of cryptorchidism seminiferous tubules increased,the nucleus of Sertoli concentrated at the base of seminiferous tubules,and the interstitial reticular fibers increased.The tissue structure of testicular tumor was unclear,collagen fibers and reticular fibers were irregularly distributed,and mast cells increased significantly compared with normal and cryptorchid groups.The immunofluorescence results showed that PGP9.5 was moderately positive in Leydig cells of normal testis,no significant expression in spermatogenic cells,strongly positive in Leydig cells and spermatogenic cells of cryptorchidism,and occasional expression in testicular tumors.NPY was occasionally expressed in normal testicular Leydig cells,but not in spermatogenic cells,strong positive expression in Leydig cells and seminiferous epithelium of cryptorchidism,high density and strong positive expression in interstitial vessels,and no obvious expression in testicular tumors.Immunohistochemical statistics showed that the expression of PGP9.5 and NPY in testicular tumor tissue were extremely significantly lower than that in normal group (P<0.01),while the expression of PGP9.5 and NPY in cryptorchidism group were significantly or extremely significantly increased (P<0.05;P<0.01).Therefore,the expression of PGP9.5 and NPY in cryptorchidism of dogs was increased suggesting that the cryptorchidism of dogs had a tendency to develop into a tumor,and was related to the degree of malignant transformation of tumor.  相似文献   

14.
试验旨在分析肽能神经递质蛋白基因产物9.5（protein gene product 9.5,PGP9.5）和神经肽Y（neuropeptide Y,NPY）在犬隐睾及睾丸肿瘤中的分布和表达,并与同年龄正常睾丸组织进行比较,为认识犬睾丸肿瘤恶变临床诊断提供参考。应用HE染色、Masson三色染色、Gomori银浸染、甲苯胺蓝染色观察各组织中网状纤维、胶原纤维及肥大细胞等组织特征,采用免疫组织化学SP法及免疫荧光法结合IPP统计分析PGP9.5和NPY在组织中的表达及定位。结果显示,正常犬睾丸生精上皮由4~7层生精细胞及Sertoli细胞构成,间质组织胶原纤维和网状纤维分布稀疏。隐睾生精小管基底膜胶原纤维厚度增加,Sertoli细胞核浓缩位于生精小管基底,间质网状纤维增多。睾丸肿瘤组织结构不清晰,胶原纤维和网状纤维无规则分布,肥大细胞较正常组及隐睾组显著增多。免疫荧光定位表明,PGP9.5在正常睾丸Leydig细胞中呈中等阳性表达,生精细胞中无明显表达;隐睾Leydig细胞及生精细胞中呈强阳性表达;睾丸肿瘤中偶有表达。NPY在正常睾丸Leydig细胞中偶见阳性表达,生精细胞中无表达;隐睾Leydig细胞及生精上皮中无表达,间质小血管管壁呈高密度强阳性表达;睾丸肿瘤组织中无明显表达。免疫组化统计表明,睾丸肿瘤组织中PGP9.5和NPY较正常组极显著降低（P<0.01）,隐睾组PGP9.5和NPY表达显著或极显著增加（P<0.05;P<0.01）。因此,犬隐睾时PGP9.5及NPY的表达增高,提示犬隐睾时已有发展为肿瘤的趋势,且与肿瘤恶变程度相关。  相似文献   

15.
Testicular tissues of 22 buffalo bulls (Bubalus bubalis) which suffered from three types of infertility were examined histologically. Nine bulls with no sexual libido showed underdeveloped seminiferous tubules; five of them also had various forms of germinal tissue hypoplasia (bilaterally complete, partial or incomplete) and in the other four the seminiferous tubules showed developed layers of germinal epithelium but no complete spermiogenesis. Among 11 bulls which had always produced poor quality semen one suffered from incomplete bilateral testicular hypoplasia and two had simple testicular degeneration; five showed marked testicular degeneration associated with fibrosis of intertubular spaces, and in three there was intertubular fibrosis and tubular stasis. In two bulls in which the quality of semen had deteriorated one showed bilateral partial testicular hypoplasia and the other had bilateral testicular degeneration with unilateral intertubular fibrosis and tubular stasis.  相似文献   

16.
Sheep have been used as translational models of human postnatal testicular development. However, the morphometric features of the normal developing testis in sheep embryos have not been previously investigated using stereology. The objective of the present work was to establish normal quantitative parameters for fetal testicular tissue components in sheep, using unbiased design-based stereological methods. Twenty-four sheep embryos were divided into four gestational age groups (9–11, 12–14, 15–17 and 18–20 weeks of gestation) on the basis of the embryos’ crown-rump length. Isotropic, systematic uniform random sections of the left testes were obtained by employing the orientator method. Testicular total volume, the absolute and proportional volumes occupied by the seminiferous tubules and interstitial tissue, as well as the seminiferous tubule length, were estimated using the point-counting system and the unbiased counting frame principle. All the parameters, with the exception of the interstitial tissue's fractional volume, gradually increased along with gestational age, with the maximum increase especially seen in the late fetal stages. The proportional volume of the interstitial tissue, on the other hand, showed a decreasing trend along with increasing gestational age. The absolute volume of the testes, of the seminiferous tubules and of the interstitial tissue, and the length of the seminiferous tubules showed a significant (p< 0.05) positive linear correlation with gestational age. Several similarities were observed with human testicular embryogenesis. The stereological data emerging from the present study might prove useful as basic contribution to the fields of andrology and embryology and stimulate further research in these areas.  相似文献   

17.
The fine structure of the tubulobulbar complex (TBC) of the ram seminiferous epithelium was studied in immersion-fixed testicular samples obtained in autumn (sheep's mating period). The TBC was visible during the last two stages of the seminiferous epithelium cycle. It originated as a tubular invagination of the Sertoli cytoplasm harbouring a complementary evagination from the spermatid head. Later, it expanded into a bulbous structure, finally becoming detached from the spermatid and apparently phagocytosed by the Sertoli cell. The significance of this transient structure is discussed and compared with previous reports for other eutherian mammals.  相似文献   

18.
试验旨在探究初情期前后生精上皮周期差异及睾丸发育过程中的形态学变化。通过测定15、30、60和90 d睾丸相关指数，结合睾丸组织形态学特征，判断香猪初情期，划分从江香猪生精上皮周期。结果显示，30 d的睾丸指数较15 d极显著升高（P<0.01），睾丸重、长轴及短轴的增长率分别为298.05%、66.42%和65.45%，60和90 d两个阶段睾丸重增长率相对稳定。形态学观察表明，从江香猪30 d时生精小管出现游离精子，完成第一次生精并进入初情期；与15 d相比，30 d生精小管面积和生精上皮厚度极显著增加（P<0.01），增长率分别为136.12%和40.19%，在60和90 d均处于稳定增长状态。睾丸细胞数统计显示，日龄增加不影响支持细胞（setoli cells，SC）数量（P>0.05），而30 d生殖细胞数（germ cells，GC）较15 d极显著增加（P<0.01）。相关分析结果发现，生殖细胞数量增加与生精小管面积增大、生精上皮厚度变化之间呈明显正相关（r=0.994；0.96）。根据生殖细胞组合形式差异，将初情期前后生精上皮分为3和8个阶段。初情期前生殖细胞以第一次减数分裂前期为主，A、B型精原细胞、SC、初级精母细胞（primary spermatocyte，Ps）、前细线期（preleptotene，PI）、细线期（leptotene，L）等生殖细胞在初情期前后生精上皮中均存在，而圆形精子（round spermatids，R）、延伸精子（elongating spermatid，E）、精子细胞（spermatozoa，S）仅存在于初情期后的生精上皮。本研究结果表明，从江香猪30 d初情，睾丸发育以生殖细胞和生精小管面积的迅速增加为主，该结果对从江香猪早熟性状挖掘、种猪选育及开发利用等有重要的指导意义。  相似文献   

19.
本研究旨在观察羊驼睾丸的出生后发育和精子发生过程中的细胞凋亡及凋亡相关蛋白Bcl2和Caspase3 的定位.取材新生、12月龄和24月龄羊驼的睾丸,用TUNEL法检测睾丸发育和精子发生过程的细胞凋亡,用免疫组织化学技术检测凋亡相关蛋白Bcl2和Caspase3在羊驼出生后发育和精子发生过程中的定位.结果显示在新生羊驼睾丸未检测到TUNEL阳性细胞,Caspase3和Bcl2表达于间质细胞,提示在新生期凋亡蛋白参与间质细胞凋亡的调节,为曲精小管的发育提供空间;12月龄羊驼睾丸TUNEL阳性细胞定位于曲精小管中央部分,Caspase3 和Bcl2定位于间质细胞和曲精小管中央生殖细胞,提示在青春期(12月龄)羊驼睾丸,细胞凋亡和凋亡相关蛋白参与曲精小管管腔形成的调节;24月龄羊驼睾丸TUNEL阳性细胞定位于精原细胞、精母细胞和精子细胞,Caspase3 和Bcl2定位于间质细胞和各个发育阶段的生精细胞,Caspase3阳性细胞在精原细胞最高,向精母细胞和精子细胞逐渐减少,Bcl2在精原细胞弱阳性表达,在血睾屏障以内的曲精小管近腔室部分呈弥散性强阳性表达,提示在性成熟(24月龄)羊驼睾丸精子发生过程中,细胞凋亡主要发生于精原细胞和早期精母细胞,Bcl2可能抑制精母细胞之后生殖细胞的凋亡.结果提示在羊驼睾丸出生后发育和精子发生过程中存在细胞凋亡现象;凋亡蛋白Caspase3和Bcl2参与羊驼睾丸发育和精子发生过程中细胞凋亡的调节.  相似文献   

20.
为了研究日粮中添加纳米硒对公羊睾丸发育的影响,试验选用体重、日龄接近的20只波尔山羊公羔羊随机分2组,1组日粮中添加0.3mg/kg的纳米硒(以硒计),另一组饲喂基础日粮,预试2周,试验期每月测量睾丸周径、长度和高度,每组阉割1只公羔,按照常规方法制作石蜡切片,观察睾丸组织结构。结果显示,3月龄时纳米硒组睾丸间质组织增生发育,4月龄时纳米硒组睾丸曲精细管中精原细胞开始发育分化;5月龄时曲精细管中可见大量的精子,而对照组间质组织以及曲精细管发育、精母细胞发育分化较纳米硒组缓慢。试验表明,日粮中添加一定浓度的纳米硒能够促进睾丸间质组织及曲精细管的发育,促进精母细胞的分化。  相似文献   

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