Seasonal spermatogenic cycle and morphology of germ cells in the viviparous lizard Mabuya brachypoda (Squamata,Scincidae)

We describe seasonal variations of the histology of the seminiferous tubules and efferent ducts of the tropical, viviparous skink, Mabuya brachypoda, throughout the year. The specimens were collected monthly, in Nacajuca, Tabasco state, Mexico. The results revealed strong annual variations in testicular volume, stages of the germ cells, and diameter and height of the epithelia of seminiferous tubules and efferent ducts. Recrudescence was detected from November to December, when initial mitotic activity of spermatogonia in the seminiferous tubules were observed, coinciding with the decrease of temperature, photoperiod and rainy season. From January to February, early spermatogenesis continued and early primary and secondary spermatocytes were developing within the seminiferous epithelium. From March through April, numerous spermatids in metamorphosis were observed. Spermiogenesis was completed from May through July, which coincided with an increase in temperature, photoperiod, and rainfall. Regression occurred from August through September when testicular volume and spermatogenic activity decreased. During this time, the seminiferous epithelium decreased in thickness, and germ cell recruitment ceased, only Sertoli cells and spermatogonia were present in the epithelium. Throughout testicular regression spermatocytes and spermatids disappeared and the presence of cellular debris, and scattered spermatozoa were observed in the lumen. The regressed testes presented the total suspension of spermatogenesis. During October, the seminiferous tubules contained only spermatogonia and Sertoli cells, and the size of the lumen was reduced, giving the appearance that it was occluded. In concert with testis development, the efferent ducts were packed with spermatozoa from May through August. The epididymis was devoid of spermatozoa by September. M. brachypoda exhibited a prenuptial pattern, in which spermatogenesis preceded the mating season. The seasonal cycle variations of spermatogenesis in M. brachypoda are the result of a single extended spermiation event, which is characteristic of reptilian species. J. Morphol. © 2012 Wiley Periodicals, Inc.     

Morphologic study of the testes from spontaneous unilateral and bilateral abdominal cryptorchid boars

Macroscopical and histological characteristics were examined in both testes from three healthy boars, three boars with unilateral abdominal cryptorchidism on the right side, and three boars with bilateral abdominal cryptorchidism. Abdominal cryptorchidism, unilateral and bilateral, provoked a significant decrease of the weight and volume of the ectopic testes. The scrotal testis of the unilateral cryptorchid boars showed an increase in its volume and weight. Cryptorchidism also induced abnormalities in the histological structure of seminiferous tubules, lamina propria, and interstitial tissue of the abdominal testes. The number of seminiferous tubules decreased; the seminiferous epithelium was constituted by few spermatogonia with an atypical pattern and by abnormal Sertoli cells. The lamina propria showed a variable degree of thickening and collagenization. The interstitial tissue was very developed but displayed a decrease in the Leydig cell population. These abnormalities were more critical in bilateral cryptorchidism than in unilateral cryptorchidism. The scrotal testis of the unilateral cryptorchid boars showed normal appearance, but a decrease of the number of seminiferous tubules was observed. Moreover, the seminiferous tubules showed impaired spermatid maturation. The alterations observed in the abdominal testes of the unilateral and bilateral cryptorchid boars were attributed to defective proliferation and differentiation of Sertoli cells and Leydig cells. The anomalies in the scrotal testis of the unilateral cryptorchid boars were due to disturbances in the Sertoli cell activity.     

The double nucleus of the sertoli cell in the lizard Anolis carolinensis

Over 90% of the Sertoli cells in the testes of adult lizards (Anolis carolinensis) are binucleate. The nuclei occur in closely associated pairs in the basal cytoplasm of the Sertoli cells that line the testis tubules. The two nuclei of a pair are of similar volume, and each usually contains one conspicuous rounded nucleolus. The average volume of individual nuclei varies from 367.8 mum(3) in spermatogenically active testes in March to 172.5 mum(3) in September, when testes are regressed. The irregular shape of the Sertoli nuclei is particularly pronounced during testicular regression. Until initiation of spermatogenesis in hatchling lizards, Sertoli cells have a single nucleus containing patches of hetcrochromatin. With the appearance of prophase stages of primary spermatocytes, a few paired Sertoli nuclei can be found, and the nuclei increasingly exhibit the homogeneous euchromatic nucleoplasm of the adult. The average volume of individual nuclei in lizards under 4 months of age is less than a third the volume of Sertoli nuclei in reproductivcly active adults. The appearance of binucleate cells at this time documents a doubling of the amount of desoxynucleic acid in Sertoli cells preparatory to their growth and expanded functions during spermatogenesis.     

Effects of cadmium chloride administration on the macroscopic and microscopic characteristics of ejaculates from Chios ram-lambs

The effects of cadmium chloride on the volume of the ejaculate, semen density, total number of spermatozoa per ejaculate, viability, grade of motility, and morphological abnormalities were studied in 3-month-old ram-lambs of the Chios breed. Two groups of seven animals each were used. For a period of 7 months, one group was treated with a daily oral dose (3 mg/kg b.w.) of cadmium chloride and the other group received the corresponding volume of doubly distilled water. Blood samples were collected for cadmium determinations, whereas semen was collected weekly. In the cadmium-treated animals, cadmium concentration in the whole blood was increased and the testes weight was lower. The volume of the ejaculate, the semen density and the total number of spermatozoa were significantly reduced by the administration of cadmium chloride. No differences were observed in the viability, the grade motility of spermatozoa, or the percentage of dead and morphologically abnormal spermatozoa between the control and the cadmium-treated animals. Histopathological examination in the cadmium-treated animals revealed the presence of lesions in the Sertoli cells, the seminiferous tubules, the primary and the secondary spermatocytes and the spermatides, whereas in the Leydig cells no significant lesions were evident.     

Cytological changes in the testes of vitamin-A-deficient rats. II. Ultrastructural study of the seminiferous tubules.

Ultrastructural study confirmed that, in rats, vitamin A deficiency initially caused the sloughing of some spermatids and spermatocytes into the lumina of the seminiferous tubules around day 3 following the initial decrease of body weight. From days 5 to 10, a considerable number of spermatocytes and spermatids, which still remained in the epithelium, underwent necrosis. Several stages of dying spermatocytes and abnormal spermatids were observed. The latter were distinguished by the presence of chromatin aggregating along the nuclear envelopes and highly vacuolated mitochondria. These cells range from single to multinucleate forms. They were incapable of differentiating further into spermatozoa and ultimately degenerated. Within the same period, Sertoli cells exhibited numerous darkly stained lysosome-like inclusions, and the upper part of their cytoplasm appeared as irregular processes, some of which were broken off and resulted in the thinning of the epithelium. From days 10 to 20, the remaining germ cells comprised mainly spermatogonia and few abnormal spermatocytes. The latter appeared enlarged and were very lightly stained. Their nuclei exhibited unusual blocks of heavily condensed chromatin amidst very highly dispersed chromatin fibers. Though their number was reduced, most of the spermatogonia appeared unaltered. Processes of Sertoli cells became even more irregular and were interrupted at certain sites by large empty spaces. Darkly stained inclusions in their cytoplasm were fewer than observed earlier.     

双峰驼睾丸和隐睾细胞外基质相关蛋白的组织化学特征及超微结构比较

为探索细胞外基质相关蛋白在隐睾双峰驼的分布情况及其组织化学特征,应用电镜技术和多种组织化学方法比较了隐睾和正常睾丸的超微结构,组织化学特点及层粘连蛋白（LN）、Ⅳ型胶原（Col Ⅳ）和硫酸乙酰肝素糖蛋白（HSPG）的分布特征。结果显示：(1)与正常睾丸间质结构相比,光镜下隐睾生精小管发育不全,间质内胶原纤维稀疏,网状纤维分布明显,间质血管及生精小管固有膜PAS及AB-PAS阳性反应较弱。电镜下,隐睾生精上皮基膜明显增生,外围I型胶原纤维较少,管周肌样细胞不典型;间质毛细血管及Leydig细胞周围纤维细胞多见,而正常睾丸在间质毛细血管及Leydig细胞周围多分布有成纤维细胞。(2) 免疫组织化学染色显示,正常睾丸组织的Col Ⅳ、LN及HSPG在Leydig细胞内均为强阳性表达,Col Ⅳ和LN在毛细血管内皮细胞强阳性表达,后者在Sertoli细胞的表达尤为明显,HSPG在精原细胞无表达;隐睾时Col Ⅳ、LN及HSPG在Leydig细胞内阳性表达均明显减弱,Col Ⅳ、LN在管周肌样细胞及毛细血管内皮细胞阳性表达也减弱明显,HSPG在精原细胞较强阳性表达,且在精子细胞呈强阳性表达。免疫组织化学图像分析结果显示,双峰驼正常睾丸组织中Col Ⅳ和LN的分布显著高于隐睾组织（P<0.05）,HSPG检测结果在正常睾丸与隐睾之间无统计学差异（P>0.01）。该研究表明,双峰驼隐睾生精小管发育异常,间质组织中合成胶原纤维的能力下降,睾丸细胞外基质的重要成分Col Ⅳ,LN与正常组差异显著与生精小管及Leydig细胞异常发育有关,而HSPG在隐睾生精上皮的强阳性表达与精原细胞发育不成熟密切相关。     

Fine structure of seminiferous tubules in antarctic seals

Summary The fine structure of seminiferous tubules from 5 crabeater, 2 leopard and 2 Ross seals showed that during the nonbreeding season the tubules were essentially similar in possessing spermatogenic and Sertoli cells. However, the tubules of leopard and Ross seals had more primary and secondary spermatocytes and spermatids than the crabeater seals. In general, the tubules were devoid of spermatozoa. The spermatids showed stages of maturation such as Golgi phase of acrosome formation, acrosomal cap formation and condensation of nuclei. Some spermatids degenerated in tubules. Both maturing and degenerating spermatids were closely associated with Sertoli cells. Junctional complexes with plaques of filaments were observed between Sertoli cells and the spermatogenic cells. Sertoli cells, irregular and polygonal, contained highly convoluted nuclei, strands of rough endoplasmic reticulum, smooth endoplasmic reticulum, Golgi complexes, small mitochondria, variable amounts of lipid droplets, lysosomes, lipofuscin granules and highly plicated plasma membranes. In brief, the spermatogenic activity had practically ceased in the testes and the animals probably secreted low levels of testosterone during the nonbreeding season.This research was supported in part by National Science Foundation Grants G.U. 30270 and G.U. 29829X from the Office of Polar Program and by NIH Grant 5 R01 AM11-376     

Effect of 17 alpha-cyanomethyl-17 beta-hydroxy-estra-4, 9-dien-3-one on reproductive organs of the male laboratory mouse

The effect of subcutaneous administration (10, 15 and 20 mg/kg body weight/day, for 21 days; and 20 mg/kg body weight/day, for 28 days) of 17 alpha-cyanomethyl-17 beta-hydroxy- estra-4, 9-dien-3-one (STS 557) on the male reproductive organs of the Parkes strain mouse was investigated. The effect of the treatment on the testis was not uniform; both regressed and normal seminiferous tubules were observed in the same section of the organ. Furthermore, the histological changes observed in the seminiferous tubules in testes of STS 557--treated mice were not different in different dosage groups. In general, in moderately affected seminiferous tubules, the germinal epithelium was thin and consisted of Sertoli cells, spermatogonia, spermatocytes and spermatids; such tubules showed presence of many vacuoles in the epithelium. In severe cases, the tubules had collapsed and were lined by mainly Sertoli cells, spermatogonia and spermatocytes. The treatment also caused marked depression in motility and concentration of spermatozoa in cauda epididymidis, weight of accessory sex glands and in the levels of sialic acid and fructose in the epididymis and seminal vesicle, respectively. By 56 days of drug withdrawal, the alterations induced in the reproductive organs returned to control levels, suggesting that STS 557 treatment induces reversible alterations in the male reproductive organs of Parkes strain mouse.     

Improvement of spermatogenesis in adult cryptorchid rat testis by intratesticular infusion of lactate.

In order to test the hypothesis that a lack of energy could be a cause of germ cell death at high temperatures, cryptorchid rats testes were infused with lactate, delivered by osmotic pumps over 3-15 days. In cryptorchid testes, the spermatids and spermatocytes were lost between 3 and 8 days. In cryptorchid testes supplemented with lactate, elongated spermatids persisted in a few seminiferous tubules at Day 15. Elimination of round spermatids occurred progressively between 3 and 15 days, mostly at stage VIII. The loss of spermatocytes increased after 8 days, and 30% of seminiferous tubules still contained meiotic or meiotic plus spermiogenetic cells at Day 15. After 8 days, the chromatin of step 8 round spermatids was abnormal and nuclear elongation did not commence. The Sertoli cell cytoplasm that was retracted toward the basal compartment of the seminiferous epithelium could not hold the germ cells of the adluminal compartment. Therefore, attachment of germ cells to Sertoli cells and the supply of lactate seem necessary for the development of germ cells at high temperatures. The improvement in spermatogenesis in cryptorchid supplemented testes for several days is a new finding.     

Cyclic AMP and genetic sterility of a male restricted (H re /+) mutant of Rattus

Restricted (H ^re /+) male rats marked by a coat color pattern have normal testes at birth. By 9 days postpartum, testes of the mutant animals are smaller than normal and by approximately 90 days of age the animals are sterile. The genetically sterile testes are totally devoid of spermatogonial cells, spermatocytes, spermatids, and spermatozoa, with only Sertoli cells remaining in the seminiferous tubules. Cyclic AMP concentrations in the whole testes (and the seminiferous tubules) of the mutant males are approximately 10–35% greater than in testes of control males when tested at intervals from 5 to 120 days of age. The possible role of excess cyclic AMP in reducing the rate of mitotic division of spermatogonial cells while enhancing differentiation of spermatogonial cells into spermatozoa is discussed. Such a change in the respective rates of mitotic and meiotic divisions would ultimately deplete the mutant testes of all spermatogonial cells.     

Elastic fibers in the tunica propria of the seminiferous tubules. Light and electron microscopic investigations.

Histological examination of numerous biopsies from mature testes, repeatedly showed irregularities of the elastin staining in the tunica propria of the seminiferous tubules. Even when abundant elastic fibers were visible by light microscopy, no elastic fibers were demonstrable in the electron microscope in ultrathin sections of testicular tubules embedded in Epon and contrasted with phosphotungstic acid (PTA). In 43 biopsies from 22 men aged 17-39 years (19 investigations of sterility and three patients with hypogonadotropic hypogonadism) we therefore checked for the occurrence of elastic fibers in the wall of the seminiferous tubules. Matrix loci of elastic fibers could indeed by demonstrated by electron microscopy using PTA and potassium permanganate (KMnO4), but only after embedding in araldite. Under these conditions, light and electron microscopic findings agreed with each other. The appearances of moderate and severe testicular tubular atrophy differed slightly from one another with regard to the amount of elastin. In the "Sertoli cells only syndrome", elastic fibers were demonstrable only outside the hyalinized inner layer. In the Klinefelter syndrome, only "uncertain" elastin loci were present, but greatly increased microfibrils were to be seen using the electron microscope. No elastic elements and only very sparse microfibrils were present in the tunica propria of the tubules of young men with hypogonadotropic hypogonadism.     

Dehydrodolichyl diphosphate synthase in Sertoli and spermatogenic cells of prepuberal rats

The specific activity of 2,3-dehydrodolichyl diphosphate synthase in homogenates of protease-treated seminiferous tubules, enriched spermatogenic cells, and Sertoli cells changed as a function of the age of prepuberal rats. The highest enzymatic activity occurred in each case in 23-day-old rats. Homogenates of pachytene spermatocytes, spermatids, or Sertoli cells had higher synthase activity than a whole testicular homogenate prepared by protease treatment of tubules. Enzymatic activity in pachytene spermatocytes expressed per mg of protein was about 1.7-fold higher than in spermatids, 5.3-fold higher than in spermatogonia, and about 8.3-fold higher than in spermatozoa. Therefore, the increase in spermatogenic cell synthase before day 23 can be accounted for by the appearance of the pachytene spermatocytes. Enzymatic activity decreased remarkably after the differentiation of spermatids into spermatozoa. Synthase activity in enriched Sertoli cell preparations was 1.5-2.3-fold higher than in spermatogenic cell preparations between days 15 and 30. Therefore, both spermatogenic cells and Sertoli cells contribute to changes in the enzymatic activity in seminiferous tubules during development. These changes may be important in regulating the availability of dolichyl phosphate for glycoprotein synthesis during early stages of differentiation.     

Seminiferous tubule involution in elderly men

The observation of different types of seminiferous tubules (from tubules with normal spermatogenesis to sclerosed tubules) in aging human testes points to the progressive stages of tubular involution in elderly men. The tubules with hypospermatogonesis (reduced number of elongated spermatids) show numerous morphological anomalies in the germ cells, including multinucleated cells. Abnormal germ cells degenerate, causing Steroli cell vacuolation. These vacuoles correspond to dilations of the extracellular spaces resulting from the premature exfoliation of germ cells. Degenerating cells that are phagocytized by Sertoli cells lead to an accumulation of lipid droplets in the Sertoli cell cytoplasm. The loss of germ cells begins with spermatids, but progressively affects the preceding germ cell types, and tubules with maturation arrested at the level of spermatocytes or spermatogonia are observed. Simultaneously, an enlargement of the tunica propria occurs. This leads to the formation of sclerosed tubules, some of which display a low seminiferous epithelium consisting of a few cells--including lipid-loaded Sertoli cells and both Ap and Ad spermatogonia--and others, showing complete sclerosis, are devoid of seminiferous epithelium. The development of tubular involution is similar to that reported after experimental ischemia, which also seems to cause nonspecific effects on the testis such as multinucleate cells, vacuoles, and increased lipids in Sertoli cells.     

The histological changes in the testis, epididymis and prostate gland of the red-bellied tree squirrel, Callosciurus erythraeus, during the growth and reproductive cycle

The male reproductive glands of the red-bellied tree squirrel, Callosciurus erythraeus, in the infantile, and prepubertal males, as well as sexually functional, degenerating and redeveloping adults were studied histologically. In the infant, testes are characterized with solid seminiferous tubules filled with primordial germ cells and Sertoli cells. Interstitial cells are sparse. The prostate is composed of condensed cell cords grouped into lobules dispersed with interlobular tissues rich in fibroblasts. In the epididymis the highly convoluted tubule is lined with a simple cuboidal or columnar epithelium and thin smooth musculature without. In the prepubertal male, germ cells are engaged actively in mitosis. Primary spermatocytes are readily recognized. Leydig cells appear in groups in the interstitial tissue. In the prostate, cell cords become highly branched and collecting tubules make their appearance. The tubules in the epididymis are enlarged in diameter but their peripheral musculature becomes thinner. In functional males, meiosis is active and bundles of spermatozoa are scattered along the central lumen. Leydig cells have their cytoplasm highly enriched. The prostate is in the secretory phase. The tubule in the epididymis is filled with sperm. In the degenerating adult, meiosis is interrupted and necrotic germ cells are detached from germinal epithelium. In the prostate, secretory and collecting ducts are eventually reduced to condensed lobules separated by interlobular fibrous tissue. The tubule in the epididymis often fills with necrotic germ cells but no sperm. In the redeveloping adult, the histology of the testes, prostate and epididymis is similar to that of the prepubertal male. However, there is more fibrous tissue in the interlobular septa in the prostate gland and thick musculature at the periphery of the tubule in the epididymis.     

Mice that express enzymatically inactive cathepsin L exhibit abnormal spermatogenesis

The finding of large, stage-specific changes in secretion of procathepsin L by rat Sertoli cells has led to the hypothesis that this proenzyme promotes the survival, replication, or differentiation of spermatogenic cells. Experiments described herein used a mouse model to test this hypothesis. To prove that mice are appropriate for this purpose, we first demonstrate that mature mouse Sertoli cells express cathepsin L mRNA in the same stage-specific manner as rat Sertoli cells and they also secrete procathepsin L. To test whether catalytically active cathepsin L is required for normal spermatogenesis, we examined the testes of 110- to 120-day-old furless mice, which express catalytically inactive cathepsin L. Morphologic examination of testes of furless mice revealed both normal and atrophic seminiferous tubules. Enumeration of atrophic tubules in furless and control mice demonstrates that lack of functional cathepsin L results in a 12-fold increase in seminiferous tubule atrophy. To determine whether lack of functional cathepsin L affects the production of male germ cells in apparently normal, nonatrophic tubules, we compared numbers in control and furless mice of preleptotene spermatocytes, pachytene spermatocytes, and round spermatids per Sertoli cell. Results demonstrate that the lack of functional cathepsin L causes a 16% reduction in formation of preleptotene spermatocytes and a 25% reduction in differentiation of these cells into pachytene spermatocyte. These results suggest that procathepsin L either directly or indirectly has two distinct functions in the testis. This proenzyme prevents atrophy of seminiferous tubules and promotes the formation of preleptotene spermatocytes and the differentiation of these meiotic cells into pachytene spermatocytes.     

Immunohistochemical study of calmodulin in developing mouse testis

The purpose of this study was to determine the localization of calmodulin in the developing mouse testis by the indirect immunoperoxidase method. In addition, the amount of calmodulin in pachytene spermatocytes, spermatids, and residual bodies isolated from the mouse testis and epididymal spermatozoa was quantitated by the adenylate cyclase activation assay and by enzyme immunoassay. The relative levels of calmodulin in the developing mouse testis and in the isolated testicular germ cells were confirmed by western transfer staining. The level of immunoreactive calmodulin was very low in the testes from immature animals. In testes from the mature mouse, calmodulin was found to be localized in spermatocytes and spermatids, but was not found in spermatogonia, Sertoli cells, and interstitial cells. By contrast, immunochemical staining of tubulin was extremely intense in Sertoli cells. Biochemical determinations also showed that pachytene spermatocytes, round spermatids, spermatozoa, and residual bodies contained 14.9 micrograms, 15.8 micrograms, 2.3 micrograms and 5.2 micrograms of calmodulin per mg of protein, respectively. Both the immunochemical and the biochemical studies revealed that levels of calmodulin were high in the spermatocytes and in the round spermatids, as compared to the level in spermatozoa. This fact strongly suggests that the large amount of calmodulin in mammalian testes may be associated primarily with meiotic divisions and/or spermatogenesis.     

Factors affecting spermatogenesis in the stallion

Spermatogenesis is a process of division and differentiation by which spermatozoa are produced in seminiferous tubules. Seminiferous tubules are composed of somatic cells (myoid cells and Sertoli cells) and germ cells (spermatogonia, spermatocytes, and spermatids). Activities of these three germ cells divide spermatogenesis into spermatocytogenesis, meiosis, and spermiogenesis, respectively. Spermatocytogenesis involves mitotic cell division to increase the yield of spermatogenesis and to produce stem cells and primary spermatocytes. Meiosis involves duplication and exchange of genetic material and two cell divisions that reduce the chromosome number to haploid and yield four spermatids. Spermiogenesis is the differentiation without division of spherical spermatids into mature spermatids which are released from the luminal free surface as spermatozoa. The spermatogenic cycle (12.2 days in the horse) is superimposed on the three major divisions of spermatogenesis which takes 57 days. Spermatogenesis and germ cell degeneration can be quantified from numbers of germ cells in various steps of development throughout spermatogenesis, and quantitative measures are related to number of spermatozoa in the ejaculate. Germ cell degeneration occurs throughout spermatogenesis; however, the greatest seasonal impact on horses occurs during spermatocytogenesis. Daily spermatozoan production is related to the amount of germ cell degeneration, pubertal development, season of the year, and aging. Number of Sertoli cells and amount of smooth endoplasmic reticulum of Leydig cells and Leydig cell number are related to spermatozoan production. Seminiferous epithelium is sensitive to elevated temperature, dietary deficiencies, androgenic drugs (anabolic steroids), metals (cadmium and lead), x-ray exposure, dioxin, alcohol, and infectious diseases. However, these different factors may elicit the same temporary or permanent response in that degenerating germ cells become more common, multinucleate giant germ cells form by coalescence of spermatocytes or spermatids, the ratio of germ cells to Sertoli cells is reduced, and spermatozoan production is adversely affected. In short, spermatogenesis involves both mitotic and meiotic cell divisions and an unsurpassed example of cell differentiation in the production of the spermatozoon. Several extrinsic factors can influence spermatogenesis to cause a similar degenerative response of the seminiferous epithelium and reduce fertility of stallions.     

Responses and coping methods of different testicular cell types to heat stress: overview and perspectives

To facilitate temperature adjustments, the testicles are located outside the body cavity. In most mammals, the temperature of the testes is lower than the body temperature to ensure the normal progression of spermatogenesis. Rising temperatures affect spermatogenesis and eventually lead to a decline in male fertility or even infertility. However, the testes are composed of different cell types, including spermatogonial stem cells (SSCs), spermatocytes, spermatozoa, Leydig cells, and Sertoli cells, which have different cellular responses to heat stress. Recent studies have shown that using different drugs can relieve heat stress-induced reproductive damage by regulating different signaling pathways. Here, we review the mechanisms by which heat stress damages different cells in testes and possible treatments.     

Morphometric studies on hamster testes in gonadally active and inactive states: light microscope findings

This study provides quantitative information on the testes of seasonally breeding golden hamsters during active and regressed states of gonadal activity. Seminiferous tubules occupied 92.5% of testis volume in adult gonadally active animals. Leydig cells constituted 1.4% of the testicular volume. The mean volume of an individual Leydig cell was 1092 microns 3, and each testis contained about 25.4 million Leydig cells. The volume of an average Sertoli cell nucleus during stage VII-VIII of the cycle was 502 microns 3. A gram of hamster testis during the active state of gonadal activity contained 44.5 million Sertoli cells, and the entire testis contained approximately 73.8 million Sertoli cells. Testes of the hamsters exposed to short photoperiods for 12-13 wk displayed a 90% reduction in testis volume that was associated with a decrease in the volume of seminiferous tubules (90.8% reduction), tubular lumena (98.8%), interstitium (72.7%), Leydig cell compartment (79.3%), individual Leydig cells (69.7%), Leydig cell nuclei (50.0%), blood vessels (85.5%), macrophages (68.9%), and Sertoli cell nuclei (34.1%). The diameter (61.1%) and the length (36.8%) of the seminiferous tubules were also decreased. Although the number of Leydig cells per testis was significantly lower (p less than 0.02) after short-photoperiod exposure, the number of Sertoli cells per testis remained unchanged. The individual Sertoli cell in gonadally active hamsters accommodated, on the average, 2.27 pre-leptotene spermatocytes, 2.46 pachytene spermatocytes, and 8.17 round spermatids; the corresponding numbers in the regressed testes were 0.96, 0.20, and 0.04, respectively. The striking differences in the testicular structure between the active and regressed states of gonadal activity follow photoperiod-induced changes in endocrine function and suggest that the golden hamster may be used as a model to study structure-function relationships in the testis.