Pathophysiology of small testes in beef bulls: relationship between scrotal circumference, histopathologic features of testes and epididymides, seminal characteristics, and endocrine profiles

Tissue sections from testes and epididymides obtained from 17 young beef bulls with scrotal circumference (SC) between 27 and 40.5 cm were studied to determine whether small testes were a manifestation of lesions or a result of less, but otherwise normal, seminiferous epithelium. The SC correlated negatively with the estimates of germinal epithelial loss and positively with seminiferous epithelial area. Four bulls with SC less than 30 cm had severe lesions in their testes. Hypoplastic tubules were characterized by Sertoli's cells only with no evidence of germinal cells. Loss of germinal cells, leaving vacuolated epithelium and atrophy, were observed in degenerated tubules. Hyperplasia of Leydig's cells was observed in the vicinity of Sertoli's cell-only tubules, resulting either from degeneration or hypoplasia, and atrophy of Leydig's cells was associated with tubules devoid of Sertoli's cells. These findings indicated that Sertoli's cells may produce a factor(s) required for maintenance and regulation of Leydig's cell function. Epididymal epithelium, especially in the head, had regressed in bulls with hypoplastic and degenerative changes in their testes. Decreased sperm concentration and motility and an increased frequency of morphologic defects were observed in the 4 bulls with testicular lesions and regressed epididymal epithelium. Blood plasma profiles of cortisol, follicle-stimulating hormone, luteinizing hormone, and testosterone were determined in the 4 bulls with SC less than 30 cm and 10 of the 13 bulls with SC greater than 30 cm. There were no statistically significant (P greater than 0.1) differences in the responses to exogenous gonadotropin-releasing hormone or base-line patterns of blood plasma follicle-stimulating hormone and luteinizing hormone between the 2 groups. However, in the bulls with SC less than 30 cm, the mean concentration of testosterone was lower, whether spontaneous (P less than 0.05) or exogenous gonadotropin-releasing hormone induced (P less than 0.1). The fact that these bulls were not deficient in gonadotropins indicated that Leydig's cell function was impaired by local factors, either the factors that caused the tubular damage or those consequent to the tubular damage.     

Intratesticular morphometric, cellular and endocrine changes in dromedary bulls exhibiting azoospermia

Twenty bulls, aged 7-12 years and selected from six dromedary farms were used in this study. Fifteen previously fertile animals were divided into fertile (controls) and infertile groups on the basis of abnormal scrotal contents following palpation and azoospermic ejaculates collected by electroejaculation. An examination of the clinical and histological findings as well as the testicular patterns of oestradiol-17beta, testosterone and histamine indicated that three bulls displayed normal ranges comparable to the controls but with bilateral spermatocoeles in the caput epididymides in conjunction with the soft texture of the testicles. Seven bulls showed moderate testicular firmness and springiness, a marked increase in testicular oestradiol-17beta and histamine concentrations, and increases in surface area, density of mast cells and percentages of seminiferous tubules containing premeiotic spermatogenic cells as well as decreases in testicular testosterone concentrations, surface area of Leydig cells and diameter of the seminiferous tubules. The remaining five infertile animals had small hard testicles, supranormal testicular testosterone concentrations, baseline values of testicular oestradiol-17beta and histamine, decreased numbers of Sertoli and mast cells, with a predominance (98.2%) of seminiferous tubules containing spermatogonia resting on a thickened tubular basement membrane. The results provide information on the relationship between gonadotrophin, testicular oestrogen, androgens and histamine as well as spermatogenesis in normal and azoospermic dromedary bulls.     

Germ cell weakness as a cause of testicular hypoplasia in bulls.

Sporadic cases of testicular hypoplasia were earlier found in bulls of the Swedish Red and White breed. An accumulation of cases have occurred since 1970 in sons of 2 outstanding progenytested bull sires, 2 F and 27 U, which had a common father, 545 B. The history and clinical examination of affected bulls varied. Some had azoospermia and very small testes at a young age, while others could be normal in all respect when they were young but had a short reproductive life and had to be culled at about 3 years of age. Most of the affected bulls were between these 2 extremes. The histologic examination showed principally different degrees of testicular degeneration. There were always some germ cells left in all affected seminiferous tubules indicating that there was not a lack of germ cells causing the hypoplasia. Germ cell weakness is obviously a hereditary condition. The sires 545 B, 2 F and 27 U had a relatively low fertility. In their pedigree were several bulls known to have had a low fertility. No sons of 2 F and only a few sons of 27 U were used for A.I. services and at present only few cases of testicular hypoplasia are seen.     

A quantitative histological study of changes in the bovine testis and epididymis associated with age.

Quantitative histological studies were performed on the testis and epididymis of 80 normal bulls from beef herds in tropical Australia. Four age groups, ranging from nine months to over 10 years were established. Volumetric proportions of parenchymal and collagenous tissues, and tubular or duct surface to tissue volume ratios were determined at the dorsal, middle and ventral testicular regions and at the head, body and tail of the epididymis for each group. Detailed volumetric analyses of the relative volumes of particular parenchymal and stromal elements were made a the middle testicular region. Lymphoid and plasma cell populations were compared in all regions, including the efferent ducts. Differences in the distribution of testicular parenchyma and collagen were found; the dorsal region had more parenchyma and less collagen than the middle and ventral areas. Progressive intertubular fibrosis attributed to age was quantified; it was most marked ventrally. Reductions in the relative volumes of germinal cells, Sertoli cells, tubular cytoplasm and parenchyma, and in tubular surface to testis volume ratios with advancing age, indicated a decrease in the capacity per unit volume of testis to produce sperm. Increased immunocyte populations in the efferent duct region in young bulls were attributed to initial antigenic exposure. Increased antigenic exposure, in association with senile degenerative changes of the genitalia, might have caused the increased immunocyte populations seen in very old bulls.     

Clinical and anatomical studies on the scrotal and pelvic genitalia of Sokoto Gudali bulls in Northern Nigeria.

The scrotal and pelvic genitalia from 2400 Sokoto Gudali bulls aged three to five years were studied clinically (by ante mortem palpation and measurement) and anatomically (by direct examination and measurement of the post mortem material). In general the difference between the mean clinical and anatomical measurements was not significant (at the 5 per cent level). Gross abnormalities observed included: testicular degeneration, 60 bulls (2.5 per cent); orchitis, 48 bulls (2.0 per cent); testicular hypoplasia, 35 bulls (1.45 per cent); epididymitis, 37 bulls (1.54 per cent); spermatic granuloma, two bulls (0.08 per cent); seminovesiculitis, 43 bulls (1.79 per cent); scrotal stryptortrichosis, 126 bulls (5.25 per cent). Lesions had no seasonal pattern and occurred randomly throughout the year.     

Scrotal circumference, seminal characteristics, and testicular lesions of yearling Angus bulls

The effect of age and body weight on scrotal circumference (SC), the effect of SC on percentage of sperm abnormalities and seminal characteristics, and the relationship of SC with testicular weight, epididymidal weight, degree of germinal epithelial loss (DGEL), and percentage of tubules graded 4 or greater (G4+) were studied in 37 Angus bulls. All bulls were from one herd and were examined at monthly intervals, during a 140-day weight gain test starting when they were 11 months old. The study was terminated when the bulls were slaughtered at 14 months of age. As age and body weight increased, SC increased (P less than 0.001). The incidence of sperm abnormalities decreased (P less than 0.001) as SC increased; however, seminal characteristics remained poor in bulls with SC less than or equal to 32 cm. Pathologic changes in 600 cross sections of seminiferous tubules from each bull were classified into 9 grades. The DGEL per 100 tubules was calculated by assigning a value to each grade according to the severity of loss of germinal epithelium. Tubules classified as G4+ were devoid of germinal cells and provided an index of irreversible loss of germinal epithelium. The SC was correlated positively with testicular weight (r = 0.91, P less than 0.001) and epididymal weight (r = 0.59, P less than 0.001) and negatively with DGEL (r = -0.48, P less than 0.01) and G4+ (r = -0.44, P less than 0.01).(ABSTRACT TRUNCATED AT 250 WORDS)     

Azoospermia in two Labrador retrievers

Azoospermia is described in two sibling Labrador Retriever dogs. Clinical investigations following failure to sire pups after normal matings revealed testicular hypoplasia and degeneration. Sperm were absent on repeated ejaculate examination in both dogs. Histopathological examination of testicular needle aspirate biopsy and whole testicle of the first dog displayed an absence of spermatids and spermatocytes. Seminiferous tubules containing Sertoli cells with or without primary spermatogonia were present in the second dog. Peritubular lymphocyte accumulation was also present in both dogs. The dogs had been conceived using frozen-thawed semen.     

Morphology and Morphometry of Seminiferous Tubules in Crioulo Horses

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.     

Ultrastructural alterations in furazolidone-induced cystic testicular degeneration in ducklings

Cystic testicular degeneration was induced in groups of ducklings by feeding furazolidone at 250, 400, 550, or 750 mg per kilogram of feed (ppm) for 4 weeks. In normal ducklings, tall, columnar Sertoli cells predominated in the seminiferous epithelium. In treated ducklings, the mildest ultrastructural alteration was cytoplasmic vacuolation of Sertoli cells. In birds with more severely affected tubules, cytoplasmic vacuolation was more severe and the cells were cuboidal or rounded. The rounded cells desquamated into the tubular lumens, eventually undergoing cytolysis. In birds with the most severely affected tubules, only extensively flattened epithelial cells lined the extremely dilated seminiferous tubules. The interstitium was edematous and compacted between the expanded tubules. Many of the testicular ultrastructural alterations in furazolidone-intoxicated ducklings were similar to those described in the testicles of sodium-intoxicated cockerels.     

Post mortem studies on infertile buffalo bulls: anatomical and microbiological findings

Twenty-two buffalo bulls suffering from three different types of infertility were slaughtered and used for this study. Except for the reproductive system, no signs of localised or generalised disease were observed. Microbiological investigations were negative for brucellosis, vibriosis, mycoplasma and other non-specific microorganisms. Nine bulls with type 1 infertility had low bodyweights and underdevelopment of testes, accessory sex glands and endocrine glands. This picture suggests a total dysfunction of the pituitary-growth-gonadal axis. One bull of this type also showed bilateral epididymitis. Four out of 11 bulls with type 2 infertility had low bodyweights and most suffered from underdevelopment of testes, accessory sex glands and endocrine glands. Six bulls of this type had lesions of either epididymitis or orchitis or both. Two of these animals showed adhesions of periorchitis. One also showed seminal vesiculitis. In two bulls with type 3 infertility, bodyweights, reproductive organs and endocrine glands were normal. In later life, they yielded poor quality semen. Semen samples collected a few months before slaughter from nine bulls with type 2 and type 3 infertility were of poor quality and had higher percentages of abnormal spermatozoa in most cases.     

Ultrasonography for monitoring reproductive function in the bull

Diagnostic ultrasonography has been widely used for examination of the reproductive tract of female cattle, but more sparingly in bulls. Typical clinical ultrasonographic examinations of bull testes are unlikely to affect semen quality or sperm production. The ultrasonographic anatomy of bull testes and accessory sex glands has been reported. Although testicular echogenicity increased (i.e. the parenchyma appeared more white) as a bull approached puberty, echogenicity was not superior to scrotal circumference as a predictor of puberty. Ultrasonography can be used to detect and characterize testicular pathology. It is noteworthy that areas of increased echogenicity (testicular fibrosis) are common, especially in young bulls, but are not associated with decreased semen quality (e.g. percentage of morphologically abnormal sperm). Neither visual evaluation nor computerized pixel analysis of testicular ultrasonic echotexture was consistently predictive of semen quality in bulls. Therefore, we concluded that the primary clinical use of ultrasonography in assessment of reproductive function in the bull is characterization of grossly detectable lesions in the testes and scrotum.     

Vimentin expression in testes of Arabian stallions

Reasons for performing study: Specific patterns of cytoskeletal filaments reflect a functional state of the cell. In testicular cells intermediate filaments (IFs) are of the vimentin type. Since it is known that Sertoli cells regulate the spermatogenic function in the male gonad, it became important to propose a system that could quantify the state of seminiferous tubular quality. To date, a Johnsen score system has never been used to equine testes. Objectives: To demonstrate the expression pattern of vimentin in testes of mature Arabian stallions and correlate its distribution with grade of seminiferous tubule impairment as indicated by a Johnsen score. Methods: For histological examination by the Johnsen method, routine haematoxylin‐eosin staining was used. Vimentin expression and its presence in testicular sections and testicular homogenates were detected by immunohistochemistry and western blot, respectively. Both analyses were performed qualitatively and quantitatively and further validated by ANOVA tests. Results: Distinct morphology of seminiferous tubules was found in testes harvested from 3 stallions. Vimentin in IFs was immunolocalised to the cytoplasm of Sertoli, Leydig and peritubular‐myoid cells. The intensity and pattern of the IFs staining was different in individual seminiferous tubules suggesting a correlation between vimentin expression and the severity of tubule degeneration. Qualitative results by immunohistochemistry and western blot were confirmed by further quantitative analyses. Conclusions: In equine testes, differential expression of vimentin was found to be correlated with the impairment of seminiferous tubules indicated by a decrease in Johnsen score. Potential relevance: The Johnsen score system may be a useful method to facilitate the identification of tubular alterations in the stallion testes. Combined histological and immunohistochemical approach may provide a detailed phenotypic classification of stallions with decreased fertility.     

Increased germ cell loss rates and poor semen quality in stallions with idiopathic testicular degeneration

Five mature stallions with poor semen quality were tentatively diagnosed as having testicular degeration of unknown cause. Testis samples from these five stallions, and from three mature stallions with normal semen quality, were obtained by castration and prepared for histomorphometry. Increased germ cell loss rates during late meiosis and spermiogenesis occurred in the stallions with idiopathic testicular degeneration. Poor semen quality, represented by a low percentage of morphologically normal, progressively motile sperm in ejaculates, appeared to be a good predictor of testicular degeneration in these stallions.     

Hormonal and histological studies in a 61XXY bull.

A Friesian bull with bilateral testicular hypoplasia was diagnosed as having a pure 61XXY karyotype. The bull displayed normal sexual behaviour but was azoospermic. At 17 months, the animal's peripheral plasma androgen levels appeared to be lower than normal, and one testicle removed one month later showed small seminiferous tubules totally lacking in germ cells. The Leydig cell volume of this testis was well within the normal range but the tubule length was rather short. At 33 months of age an increase in peripheral plasma androgen levels was noted. In the remaining testis there had been both a considerable rise in Leydig cell volume and a fall in tubule length. These findings may be explained by the interaction of three factors; the effects of the abnormal karyotype, the increased maturity of the animal at 33 months and the reaction of the remaining testis to unilateral castration.     

Stereological analysis of Wistar rat testis during early post-natal development

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.     

A morphological study of simple testicular cysts in the ostrich (Struthio camelus)

Simple testicular cysts are rare in mammals and of unknown aetiology, but dietary conditions have been implicated in this phenomenon in poultry. This study characterises the structural features of simple intratesticular cysts in the ostrich. Seven testes from a total of 15 sexually mature ostriches slaughtered during the breeding season were used. The testes contained multifocal, fluid-filled, unilocular cysts which were lined by a simple squamous or low cuboidal epithelium and surrounded by a thick layer of fibrous connective tissue. The cysts developed within seminiferous tubules and displayed morphological features similar to those reported in man and domestic poultry. The testis parenchyma revealed several foci composed of intermingled normal seminiferous tubules and variably sized intratesticular cysts. The atrophic tubules lay within a mass of hyperplastic, fibroblastic intertubular connective tissue in the proximity of large cysts and their formation appeared to result from hydrostatic pressure exerted by cysts. Morphological evidence supports a continuous process of cyst formation in the affected testis and a concomitant progressive loss of atrophic seminiferous tubules. A pathogenetic scenario of cyst formation and the effect of simple cysts on testicular histology has been proposed. Although the course of this phenomenon remains unknown, its impact on the fertility of this economically important bird deserves closer scrutiny.     

Flow cytometry evaluation of testicular and sperm cells obtained from bulls implanted with zeranol

Flow cytometry of testicular and sperm cells was used to evaluate effects of pre-weaning zeranol implants on spermatogenesis. Forty five Angus-Simmental bulls were randomly assigned to three treatment groups of 15 bulls each: no implant, one implant at 30 d of age and two implants, one at 30 and the second at 120 d of age. Prior to slaughter at approximately 15 mo, semen was collected from 30 bulls, 10 of each group. Following slaughter, testes were weighed, and testicular biopsies and vas deferens sperm obtained from the same 30 bulls. Testicular and sperm cells were stained with acridine orange and measured by flow cytometry. Proportions of testicular haploid, diploid and tetraploid cells were determined by relative amounts of green (DNA) and red (RNA) fluorescence. Treatment of sperm at low pH prior to acridine orange staining potentially induces partial denaturation of DNA, detectable by the metachromatic shift from green (native DNA) to red (single-stranded DNA) fluorescence. The effect of this shift was quantified by alpha-t [alpha t = red/red + green) fluorescence]. Nonimplanted bulls had heavier (P less than .01) testicular weights than treated bulls. The proportion of haploid cells was greater (P less than .02) and diploid cells less (P less than .03) in testes of nonimplanted bulls. Sperm from implanted bulls had altered chromatin structure, indicated by higher (P less than .05) alpha t values. Flow cytometry is an effective means for detecting changes in testicular cell subpopulations and chromatin structure of sperm.     

Histologic pattern of testicular regrowths in caponized tom turkeys.

Testicular regrowths were observed in 10 of 21 tom turkeys between 28 and 32 weeks old, which was between 19 and 23 weeks after surgical caponization at 9 weeks of age. Regrowths were not observed in younger caponized toms. Two types of histologic patterns that differed from the normal pattern were observed in these regrowths. The first pattern was observed in seven regrowths and was characterized by a higher density of seminiferous tubules and more interstitial cells. The second pattern was seen in three regrowths and was characterized by extensive intertubular fibrosis, tubular detachment, and an increased number of interstitial cells. No correlation was found between the presence of these regrowths and plasma testosterone levels. The interstitial cell hyperplasia in all regrowths possibly was related to a diminished negative feedback by the endogenous testosterone on the release of luteinizing hormone from the pituitary. The appearance of regrowths at this age probably was related to the onset of normal physiological puberty.     

Growth and Development of Testes in Domesticated and Hybrid(wild × domesticated)Yak Bulls

Testicular tissue was studied in domesticated yak and in wild yak × domesticated yak(F1 and F2)bulls at 6,12,18 and 24 months of age by stereology for quautitative histology and by comparative studies on the lactate dehydrogenase(LDH)isoenzyme spectrum, LDH activity and the percentage content of LDH isoenzymes in testes. The results indicated that all three types of yak were similar in both the characteristics of ultrastructure of testicular tissue and the degree of germ cell development. The process of spermatogenesis was initiated and sperm were produced for the first time at the age of 12months in all three yak types. All yak types exhibited similar age-related, increases in weight of testes,volume density of both the seminiferous tubules and seminiferous epithelium and height of seminiferous epithelium but all these indexes were slightly affected by season. The number of LDH isoenzyme bands after electrophoresis varied with age as follows: four bands were present at 6 months of age, five bands at 12 and 18 months and six bands at 24 months of age. The sixth band was LDH -x ,which appeared between the LDH4 and LDH5 band. These results indicated that yak bulls reach sexual maturity at 24months of age and that puberty is not affected by infusion of wild strains.     

Morphological features of the seminiferous epithelium in cat (Felis catus, L. 1758) testes

The aim of the present study was to assess the changes in the germinal epithelium in cats of different ages. Routine histological staining was applied to perform morphological and stereological examinations. The animals were divided into five groups according to age: under 8 months (n=28), 8-12 months (n=30), 12-36 months (n=33), 3-6 years (n=14) and older than 6 years (n=13). The appearance of the gonads of the males in the first group varied the most. The seminiferous tubules of the youngest cats consisted of a monolayer of supporting cells and a few spermatogonia. No tubular lumina were present, and the diameters of the seminiferous tubules reached 132.5 microm. We noted the typical arrangement of gametogenic cells with a tubule diameter of 191.83 microm in the second group. We observed multilayer germinal epithelia with the most significant production of gametes and a seminiferous tubule diameter of 202.61 microm in the third group. The diameters of the seminiferous tubules of the forth and fifth groups were 193.38 microm and 191.84 microm, respectively. The obtained data revealed that the most intensive morphological diversification of the seminiferous epithelium in cats occurs at about 7-8 months of age. The diameters of seminiferous tubules were highest in the third group of cats, and the activity of spermatogenesis of this group, expressed as the number of sperm per 10 mm(2), was also the most distinctive. The spermatogenesis process was most evident in cats between 12 and 36 months of age, which was also when the sperm concentration was highest per estimated surface.