Histopathology of incidental findings in cynomolgus monkeys ( macaca fascicularis ) used in toxicity studies

The purpose of our publication is to widely communicate pictures of spontaneous findings occurring in cynomolgus monkeys. Focal lymphoplasmacytic infiltration is commonly seen in the general organs. The frequency and severity of these lesions may be influenced by the administration of drugs with an effect on the immune system. Lymphoplasmacytic infiltration in the lamina propria of the stomach is also frequently seen in cynomolgus monkeys, and it is caused mainly by a Helicobacter pylori infection. Various degrees of brown pigments are observed in various organs, and it is possible to distinguish the material of the pigments by its morphological features and site. A focal/segmental glomerular lesion is occasionally seen in a section of the kidney, and the minimal lesion has no influence on the urinalysis. We showed the common glomerular lesions in HE-stained sections, as well as in PAM- or PAS-stained sections, for understanding the details. Young and pubertal monkeys are usually used in toxicity studies; therefore, understanding various maturation stages of the genital system is important. In particular, the female genital system needs to be understood in the morphology, because their cyclic changes are different from other laboratory animals. Thus, we present the normal features of the cyclic changes of the female genital organs. Furthermore, we provide more information on spontaneous findings in cynomolgus monkeys for exact diagnoses in toxicity studies.     

Immunohistochemical study of osteopontin in boar testis

The expression of osteopontin (OPN) in boar testis was studied. Western blot analysis detected 66- and 32-kDa OPN immunopositive bands in the testes of adult boars. In postnatal piglets, the 66-kDa OPN band was detected in the testes, but not the 32-kDa band. In the newborn testis, OPN immunostaining was seen in gonocytes and in some supporting cells in the seminiferous tubules, as well as in interstitial Leydig cells. In the adult boar testis, OPN immunoreactivity was detected in seminiferous tubules with varying intensities. Intense OPN immunostaining was seen in the residual bodies and acrosomes in the spermatids while, occasionally, OPN immunostaining was seen in spermatogonia and various stage of spermatocytes but in few Sertoli cells in the seminiferous tubules. In addition, Leydig cells in adult boars were weakly immunostained with OPN. These findings suggest that OPN is detected in the majority of germ cells and is involved in spermatogenesis in boar testis.     

Characteristics of structures and lesions of the eye in laboratory animals used in toxicity studies

Histopathology of the eye is an essential part of ocular toxicity evaluation. There are structural variations of the eye among several laboratory animals commonly used in toxicity studies, and many cases of ocular lesions in these animals are related to anatomical and physiological characteristics of the eye. Since albino rats have no melanin in the eye, findings of the fundus can be observed clearly by ophthalmoscopy. Retinal atrophy is observed as a hyper-reflective lesion in the fundus and is usually observed as degeneration of the retina in histopathology. Albino rats are sensitive to light, and light-induced retinal degeneration is commonly observed because there is no melanin in the eye. Therefore, it is important to differentiate the causes of retinal degeneration because the lesion occurs spontaneously and is induced by several drugs or by lighting. In dogs, the tapetum lucidum, a multilayered reflective tissue of the choroid, is one of unique structures of the eye. Since tapetal cells contain reflecting crystals in which a high level of zinc has been demonstrated chemically, drug-induced tapetum degeneration is possibly related to zinc chelation. The eye of the monkey has a macula similar to that of humans. The macula consists only of cones with a high density, and light falls directly on the macula that plays an important role in visual acuity. Macular degeneration occurring in monkeys resembles histopathologically that of humans. Hence, the eye of the monkey is a suitable model to investigate macular degeneration and to assess drug-induced macular lesions.     

Evaluation of pancreatic forceps biopsy by laparoscopy in healthy beagles

The effects of laparoscopic biopsies were determined in four healthy laboratory beagles. Biopsies were taken from the pancreas of three dogs and from the peripancreatic fat of one dog. Clinical examinations and blood sampling for hematologic and biochemical tests were performed before laparoscopy and weekly throughout each dog's participation in the study (7 or 21 days). No clinical signs of pancreatitis were observed, and hematologic and biochemical parameters remained within normal limits in three dogs. One dog exhibited a transient increase in trypsinlike immunoreactivity, amylase, and lipase. Minor adhesions between the pancreas, small intestine, and peritoneum were observed macroscopically in this dog. Histologically, granulation tissue and a mild nonsuppurative inflammation in the pancreas were present. No abnormal changes were seen macroscopically or histologically in the other two dogs for which pancreatic biopsies were performed. Thus, laparoscopy appears to be safe, with neither permanent abnormalities in blood parameters nor changes in clinical health occurring during or after the procedure in healthy beagles.     

Idiopathic cutaneous and renal glomerular vasculopathy of greyhounds

An idiopathic disease involving skin and occasionally kidneys was seen in kenneled and racing greyhounds. Hemorrhages, fibrinoid arteritis, thrombosis, and infarction with deep, slowly healing ulcers characterized the skin lesions. Peracute renal glomerular necrosis, particularly involving afferent arterioles with intravascular coagulation in glomerular capillaries were the distinctive findings in affected kidneys. A complex pathogenesis of this disorder was suspected in which genetic predisposition plays a prominent role.     

Idiopathic extramural coronary arteritis in beagle and mongrel dogs

Hearts obtained from 119 toxicological experiments on dogs during a 21-year period (1965-1986) were evaluated histologically to determine the incidence and characteristics of focal microscopic inflammatory lesions of the extramural coronary arteries. Lesions were encountered in 23% of 119 experiments. The average overall incidence was 2.3% of 1,905 control and chemically treated male and female beagle hearts (3.1% of male and 1.3% of female control beagles, and 1.8% of male and 2.8% of female treated beagles). Lesions were seen in 4.7% of 127 random-source mongrel dogs. Histologically, lesions were characterized by adventitial infiltrates of mononuclear cells, areas of mural necrosis, and inflammatory cell infiltrates in both mural and subendothelial regions. In the latter region, fibrosis developed separating the intima from the internal elastic membrane. Lesions occurred in the right and left coronary arteries and in the dorsal, circumflex, and ventral descending branches of the left coronary artery. Vascular lesions were not present in the intramural coronary vessels or in vessels of other organs in affected animals. More extensive sampling of the extramural coronary arteries revealed an incidence of 5-9%. The lesion of focal extramural coronary arteritis was idiopathic, and not a manifestation of the polyarteritis syndrome of dogs.     

Spontaneous Gingivitis Related to Hair Penetration in Rats

Maxillary gingivae from male and female Crl:CD(SD) rats at 12, 16, 21, and 34 weeks of age were examined histologically. The incidence of gingivitis was approximately 40%, with no age or sex predilection, and was most frequent between the first and second molar. Lesions were characterized by acute focal neutrophilic infiltration into the gingival mucosa, occasionally with inflammatory exudate. In severe cases, inflammation extended to the periodontal ligament with abscess formation, and adjacent alveolar bone destruction/resorption. The most characteristic finding was the presence of hair shafts associated with the lesion, which was observed in approximately 80% of the rats with gingivitis. These findings suggest that molar gingivitis occurs in rats from an early age and persists thereafter, and that the main cause of gingivitis in rats is hair penetration into the gingiva. It would be prudent to keep these background lesions in mind as potential modifiers in toxicity studies.     

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.     

Histological observations of the reproductive organs of the male dog from birth to sexual maturity.

Development of the testis, epididymis and prostate in 53 male beagles was examined histologically with PAS-hematoxylin stain from birth to sexual maturity. The diameter of the seminiferous tubules of the testes was less than 100 microns until 20 weeks of age, however, it increased markedly between 22 and 28 week of age, reaching 180 +/- 7 (mean +/- SD) microns at 28 weeks of age. Only Sertoli cells and gonocytes (or spermatogonia) were detected in the seminiferous tubules until 16 weeks of age. Spermatocytes and spermatids appeared in the tubules at 20 and 22 weeks of age, respectively. Spermatozoa were first observed in the testes of 2 of the 5 dogs at 26 weeks of age and were found in the testes of all the 3 dogs at 28 weeks of age. The diameter of the ducts in the cauda epididymidis was 146 +/- 4 microns at 20 weeks of age. Thereafter it increased markedly, reaching 341 +/- 14 microns at 28 weeks of age. The height of the epithelium and stereocilia in the ducts of the caput epididymidis increased markedly at about 28 weeks of age. A large number of spermatozoa was seen in the lumens of the ducts of the corpus and cauda epididymidis after 32 weeks of age. The shape of the lumens in the glandular alveoli of the prostate became irregular as a result of projection of the glandular epithelium into the enlarged lumens and the epithelial cells of the alveoli became PAS-positive at 24 weeks of age.(ABSTRACT TRUNCATED AT 250 WORDS)     

Pilot investigation of a model for canine atopic dermatitis: environmental house dust mite challenge of high-IgE-producing beagles, mite hypersensitive dogs with atopic dermatitis and normal dogs

Although canine atopic dermatitis (cAD) is common, few models are available. The aim of this study was to evaluate high-IgE beagles epicutaneously sensitized to house dust mite (HDM) as a possible model for cAD. Six high-IgE beagles were environmentally challenged with HDM using various doses and protocols. Similar challenge protocols were used in positive and negative control dogs: three dogs with naturally occurring cAD and positive intradermal skin test (IDT) to HDM and three normal dogs without history of skin disease and negative IDT to HDM. All high-IgE beagles and all atopic dogs developed severe cutaneous lesions and pruritus after challenge. Lesions were erythematous papules and macules in contact areas such as face, ears, ventral abdomen, groin, axillae and feet. They were first visible after 6 h and increased in severity over time. No normal dog developed pruritus or lesions. Biopsies of representative lesions in the high-IgE beagles were taken for histopathology and immunohistochemistry. There was superficial perivascular dermatitis with mononuclear infiltrates and spongiosis. Lymphocytes and eosinophils accumulated in small epidermal micro-abscesses with hyperplasia of epidermal IgE-bearing dendritic cells. These findings suggest that this colony of high-IgE beagles develops a dermatitis that clinically, histopathologically and immunologically resembles the naturally occurring canine disease. It is also concluded that this modality of challenge is not irritating to normal dogs but induces flare-ups in hypersensitive atopic dogs.     

Expression of constitutive endothelial, neuronal and inducible nitric oxide synthase in the testis and epididymis of horse

The expression of three isoforms of nitric oxide synthase (NOS) were examined in the testis and epididymis of a thoroughbred horse. Immunohistochemical studies demonstrated the presence of eNOS immunostaining in some germ cells in the seminiferous tubules and in vascular endothelial cells in the interstitial tissues. Interstitial cells, most likely Leydig cells, were also intensely immunopositive for eNOS. The pattern of immunostaining for nNOS was similar to that for eNOS in the testis. Weak expression of iNOS was detected in the seminiferous tubules of the testis, but intense expression was found in interstitial cells. Inducible NOS was also strongly detected in stereocilia, sperm, epithelium and connective tissue of the epididymis of normal horses. These findings suggest that three isoforms of NOS are expressed in the testis and epididymis of horse and that they play important roles in the biology of interstitial cells that produce testosterone, as well as in spermatogenesis in the seminiferous tubules.     

Two cases of spontaneous pseudohermaphroditism in Cynomolgus monkeys (Macaca fascicularis)

Disorders of genital development occur in all mammals. Hermaphroditism is a condition where the subject has genital organs of both sexes. True hermaphrodites have both ovarian and testicular tissue. Pseudohermaphrodites have only one type of gonadal tissue according to which they are classified as male or female pseudohermaphrodites. Two cases of spontaneously occurring pseudohermaphroditism in Cynomolgus monkeys (Macaca fascicularis) were seen here during 1999-2001. Both animals had female external genitalia, but each was found to have testicular tissue.     

Expression of Steroid Hormone Receptors in the Genital Structures of a True Hermaphrodite Pug Dog

Hermaphroditism is a rare and a not well‐understood disordered sexual development (DSD) in dogs. The objective of the study was to analyse the sex steroid hormone receptor (STHR) expression patterns in the internal genital structures, because the responsiveness of the different tissue types to the steroid hormones may have a key role in pathological alterations based on DSDs. Furthermore, the adhesion molecule β‐catenin was investigated by means of immunohistochemistry because of its important role in development, tissue integrity and disease. Molecular sexing was performed via PCR targeting DBX/DBY genes to identify the pug dog as a true XX hermaphrodite. The portions of uterine tissue revealed comparable expression patterns for STHRs as investigated in normal female reproductive tissue. In the male parts, β‐catenin showed strong expression in the Sertoli cells of the seminiferous tubules; this was in contrast to normal testicular tissue. Likewise, the layers of smooth muscle actin‐positive cells surrounding the seminiferous tubules were reduced in the hermaphrodite. The results of this study deepen the knowledge of tissue characteristics in a hermaphrodite dog and highlight the importance of early diagnosis because the STH responsiveness in maldeveloped reproductive tissue might lead to serious problems for the dog.     

Leydig cell hyperplasia in an ENU-induced mutant mouse with germ cell depletion

Repro22 is an N-ethyl-N-nitrosourea (ENU)-induced mutation in mice showing depletion of both male and female germ cells. In the present study, we investigated the male phenotypes of the mutant mouse at the adult stage. The repro22/repro22 homozygous mice showed reduced body weights as well as markedly reduced testis weights. Histological examination of the testes at 4 and 10 months of age showed no germ cells in the seminiferous tubules of the affected testis while a number of Sertoli cells were observed in the tubules. In addition to the germ cell depletion, the testes of the affected mouse contained expanded intertubular spaces that were filled by Leydig cell-like interstitial cells. These interstitial cells were confirmed to be Leydig cells by immunohistochmical staining using anti-3beta-HSD antibody. The estimated number of Leydig cells in the affected testes at 10 months of age increased approximately 2 fold compared with those of normal testes. Furthermore, the plasma testosterone levels of the affected mice at 10 months of age were significantly higher than those of the normal mice. These findings indicated that the repro22/repro22 mouse developed hyperplasia of Leydig cells that was presumably caused by the absence of germ cells in the seminiferous tubules.     

Recording uterine motility in the nonanesthetized bitch

Spontaneous and drug-induced uterine motility (UM) was recorded in 5 nonanesthetized bitches for 2 to 4 days. Catheter-tip pressure transducers were surgically implanted in 1 uterine horn, tunneled subcutaneously to exit from the skin over the dorsal lumbar area, and protected by a bandage. On the day after implantation, spontaneous UM was recorded in the awake bitch. Effects of IV prostaglandin (PG) F2 alpha (5 micrograms/kg of body weight) and oxytocin (0.05 USP U/kg) and IM PGF2 alpha (25 micrograms/kg) were measured. Estradiol (1 to 25 micrograms/kg) was administered and the study was repeated 24 hours later. In awake bitches, spontaneous UM was 190% greater than UM in anesthetized bitches. Uterine motility was increased by more than 100% after IV PGF2 alpha or oxytocin and by 52% after IM PGF2 alpha. Estradiol abolished spontaneous UM, but did not affect drug-induced responses. Seemingly, spontaneous and drug-induced UM can be documented in the nonanesthetized bitch.     

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.     

Cystic testicular degeneration in furazolidone toxicosis of sexually immature ducks

Cystic testicular tubular dilatation was seen in ducklings fed a ration containing furazolidone at 250, 400, 550, or 700 ppm for 28 days. Gross evidence of cystic testicular dilatation was observed at necropsy in 16% (32/203) of the ducklings that survived to the end of the study. Gross testicular lesions consisted of various degrees of enlargement with increased translucency in moderately to severely enlarged testicles. Histological evidence of cystic testicular dilatation was present in 45% (41/91) of the testicles examined. Histologically, the tubules were in various states of dilatation with attenuation of the seminiferous epithelium proportional to the severity of dilatation. In the most severely affected testicles, tubules were greatly dilated, distorted, and fluid-filled, with extensively flattened epithelium visible on the inner margin of the tubule as a thin rim of cytoplasm with a protuberant nucleus. Interstitial tissues were compressed to thin septa between the dilated tubules.     

黄鳝性逆转过程中性腺形态学初步观察

试验通过对性逆转过程中雌、雄鳝以及雌雄间体鳝的性腺的形态学进行观察 ,结果显示 ,雌鳝性腺大部分含肉眼可见的卵粒 ,但各时期卵巢的卵粒大小不一。雌雄间性阶段黄鳝性腺肉眼仅见不同形态的卵粒 ,部分卵粒极少 ;组织切片既可观察到卵母细胞 ,还可发现结缔组织纵隔和在纵隔上形成的管状结构的早期精细管 ;而雄鳝阶段黄鳝性腺多呈乳白色带有黑色斑点 ,带有较多且大的黑色斑点性腺可能是卵母细胞退化凋亡痕迹 ,其切面中有较稀疏精母细胞 ,可能属早期的精巢 ;乳白色性腺中黑色斑点极少 ,精母细胞相对较密集 ,可能是成熟期的精巢。试验表明黄鳝“性逆转”在形态学上具有明显的阶段性特征