The INHAND (International Harmonization of Nomenclature and Diagnostic Criteria for Lesions in Rats and Mice) Project (www.toxpath.org/inhand.asp) is a joint initiative of the Societies of Toxicological Pathology from Europe (ESTP), Great Britain (BSTP), Japan (JSTP) and North America (STP) to develop an internationally accepted nomenclature for proliferative and nonproliferative lesions in laboratory animals. The purpose of this publication is to provide a standardized nomenclature for classifying microscopic lesions observed in the female reproductive tract of laboratory rats and mice, with color photomicrographs illustrating examples of some lesions. The standardized nomenclature presented in this document is also available electronically on the internet (http://www.goreni.org/). Sources of material included histopathology databases from government, academia, and industrial laboratories throughout the world. Content includes spontaneous and aging lesions as well as lesions induced by exposure to test materials. There is also a section on normal cyclical changes observed in the ovary, uterus, cervix and vagina to compare normal physiological changes with pathological lesions. A widely accepted and utilized international harmonization of nomenclature for female reproductive tract lesions in laboratory animals will decrease confusion among regulatory and scientific research organizations in different countries and provide a common language to increase and enrich international exchanges of information among toxicologists and pathologists.

Stress often occurs during toxicity studies. The perception of sensory stimuli as stressful primarily results in catecholamine release and activation of the hypothalamic-pituitary-adrenal (HPA) axis to increase serum glucocorticoid concentrations. Downstream effects of these neuroendocrine signals may include decreased total body weights or body weight gain; food consumption and activity; altered organ weights (e.g., thymus, spleen, adrenal); lymphocyte depletion in thymus and spleen; altered circulating leukocyte counts (e.g., increased neutrophils with decreased lymphocytes and eosinophils); and altered reproductive functions. Typically, only some of these findings occur in a given study. Stress responses should be interpreted as secondary (indirect) rather than primary (direct) test article-related findings. Determining whether effects are the result of stress requires a weight-of-evidence approach. The evaluation and interpretation of routinely collected data (standard in-life, clinical pathology, and anatomic pathology endpoints) are appropriate and generally sufficient to assess whether or not changes are secondary to stress. The impact of possible stress-induced effects on data interpretation can partially be mitigated by toxicity study designs that use appropriate control groups (e.g., cohorts treated with vehicle and subjected to the same procedures as those dosed with test article), housing that minimizes isolation and offers environmental enrichment, and experimental procedures that minimize stress and sampling and analytical bias.This article is a comprehensive overview of the biological aspects of the stress response, beginning with a Summary (Section 1) and an Introduction (Section 2) that describes the historical and conventional methods used to characterize acute and chronic stress responses. These sections are followed by reviews of the primary systems and parameters that regulate and/or are influenced by stress, with an emphasis on parameters evaluated in toxicity studies:

Abstract. Canine distemper virus (CDV) infection occurred in captive leopards (Panthera pardus), tigers (Panthera tigris), lions (Panthera leo), and a jaguar (Panthera onca) in 1991 and 1992. An epizootic affected all 4 types of cats at the Wildlife Waystation, San Fernando, California, with 17 mortalities. CDV-infected raccoons were thought to be the source of infection in these cats. Two black leopards died at the Naibi Zoo, Coal Valley, Illinois, and 2 tigers died at the Shambala Preserve, Acton, California. Initial clinical signs were anorexia with gastrointestinal and/or respiratory disease followed by seizures. Canine distemper virus was isolated from 3 leopards, 3 tigers, and 3 lions that died or were euthanized when moribund. Monoclonal antibody testing identified the virus isolates as CDV. Gross and histopathologic findings were similar to those found in canids with distemper with a few exceptions. There were fewer lesions in the brain, and there was a pronounced type 2 cell proliferation in the lung, with inclusion bodies and CDV antigen demonstrated by immunohistology. Neutralizing antibody to CDV was found in high titers in serum from most animals but was absent or was found only in low titers in some cats that succumbed after CDV infection. There was a marked difference in neutralizing antibody titers when tests were done with different strains of CDV.Canine distemper virus (CDV) is a common pathogen in dogs and is well known in canids, mustelids, procyonids, and viverrids.2 Encephalitis in javelinas (collared peccaries) after natural infection with CDV occurred in Arizona. 4 Experimental infection with CDV in domestic cats and pigs resulted in seroconversion but no clinical disease. 6 Morbilliviruses closely related to CDV have been isolated from epizootics in seals, 26 dolphins, 14 and porpoises. 32A major outbreak of canine distemper (CD) There are other reports of encephalitis in large cats. A fatal nonsuppurative encephalitis in lions and tigers was observed in a safari park in Germany. It was believed to be caused by an infectious agent that has not been isolated but was found to be unrelated to CDV by serology and immunohistology. 30 A similar encephalitis of unknown origin is seen in domestic cats in the United States and Europe.21,31 A paramyxoviruslike agent was associated with demyelinating lesions in the CNS and optic neuritis in cats. 13 This agent has 277

An understand ing of form and function is important for exam ination of the m ale reproductive tract. A basic understand ing of spermatogenesis and horm onal function in the reproductive tract is essential for the pathologists in this evaluation. Gross and histologic reproductive changes need to be distinguished from normal variation and correlated with the reproductive status of the animal. This is especially important when correlating histologic changes with organ weight and other reproductive parameters, such as seminal analysis data. Sexual maturity of animals and tissue handing can impact interpretation. Sexual imm aturity of preclinical safety animals can present challenges for accurate identi cation of compound-related changes. Likewise, proper handlin g of un xed reproductive tissues and appropriate selection of a xation protocol are important in avoiding artifacts that may interfere with the microscop ic evaluation. The histopathology technician needs to recognize testicular landmark s that allow for correct orientation at trim ming so the pathologist can assess not only the morphology of sem iniferous tubules but also the out ow tract. For the m ost effective evaluation of the male reproductive tract, the testes and epididymides should be examine d concurrently. Although the term ''staging'' is often used inappropriately, the pathologist should review testicular tissues in a ''stage-aware'' manner. This article reviews gross and histologic changes of the m ale reproductive tract as well as tissue orientation and xation to assist in accurate interpretation of potential treatm ent-related change s in m ale reproduction.

Cricket frogs (Acris crepitans) from several different sites in Illinois were collected to assess the effects of environmental contamination on the prevalence of intersex gonads. Of 341 frogs collected in 1993, 1994, and 1995, 2.7% were intersex individuals. There was no statistically significant relationship between the chemical compounds detected and cricket frog intersexuality. However, there was an association approaching significance (p = 0.07) between the detection of atrazine and intersex individuals. A comparison of reference sites with sites that had point polychlorinated biphenyl (PCB) and polychlorinated dibenzofuran (PCDF) contamination revealed a significant relationship between sex-ratio reversal and contamination with PCBs and PCDFs. The sex ratio of juvenile frogs studied from three sites with PCB and PCDF point contamination favored males over females, which was the opposite of the sex ratio in control ponds (p = 0.0007). The statistically significant correlation between organochlorine contamination and sex-ratio reversal suggests PCBs and PCDFs can influence cricket frog sexual differentiation. The current study suggests that in cricket frogs, sex ratios and the prevalence of intersex gonads are altered by environmental contamination.ImagesFigure 1Figure 2

The purpose of this study was to determine the long-term effects of lasofoxifene, a new selective estrogen receptor modulator, on bone mass, bone strength, and reproductive tissues in ovariectomized (OVX) rats. Sprague Dawley female rats at 3.5 months of age were OVX and treated orally with lasofoxifene (60, 150, or 300 microg/kg x d) for 52 wk. The urinary deoxypyridinoline/creatinine ratio was significantly lower in all lasofoxifene-treated OVX rats compared with OVX controls at wk 26. Peripheral quantitative computerized tomography analysis of proximal tibial metaphysis showed that the significant loss in trabecular content and density induced by OVX was significantly prevented by lasofoxifene treatment. Proximal tibial and lumber vertebral trabecular bone histomorphometric analysis showed that all doses of lasofoxifene significantly reduced OVX-induced bone loss by decreasing bone resorption and bone turnover. The ultimate strength, energy, and toughness of the fourth lumbar vertebral body in OVX rats treated with all doses of lasofoxifene were significantly higher compared with those in OVX controls, and did not differ significantly from those in sham controls. Uterine weight in OVX rats treated with lasofoxifene was slightly, but significantly, higher when compared with that in OVX controls, but was still much less than that in sham controls. No abnormal finding associated with lasofoxifene was observed with uterine histology examination. In summary, long-term treatment with lasofoxifene preserves bone mass and bone strength and does not adversely affect the uterus in OVX rats. These data suggest that lasofoxifene is an effective antiosteoporosis agent, and its efficacy and safety can be maintained over an extended period of time.

Materials and Methods seq ue n t rep ort d etai led the progr ession and h ist ol ogic patterns o f a co ngen ita l m elanocytic tumor on the withers ofa Quarterhorse.' Two horses with congenital melanomas were later described as malignant neoplasms, d esp it e an apparently benign course following surgica l excision." In this report, the te rm m elano cytoma will be used to con nota te a benign m elanocyti c tumor (benign m elanoma). W e will review the signalment and histopathologic features of four congen ital and 14 acquired melanocy tic tumors in horses less th an 2 yea rs of age. Subseq ue nt additional information o f th e biological behavior was obtained for 15 of the tumors. Vet Path oI28:363-369 (1991) Abstract. In a retrospective study, cutaneo us melanocytic tum ors from 18 horses, less than 2 years old, were exam ined histopath ologically and clinical follow-up requested. Melanocytom as (benign melanoma s) occurred in a variety of breeds and in horses of varied coat color. Th e age of the horses at the time of biopsy ranged from 3 weeks old to 2 years old. Four melanocytom as were congenital, I I melanocytoma s were acqui red by I year of age, and three were acquired prior to 2 years of age. Of the 18 horses, five were male, and 13 were female. All tum ors were solitary and located on the legs or trunk; none were in the perineal region. Ulceratio n of the ove rlying epider mis was commo n. Tumors were generally localized and were not encapsulated. Th e tum ors had a variety of cell patt ern s ranging from sheets, to streams, or nests of mclanocytes. Cellular morphologic findings also ranged from epithelioid, to a mixture of epithelioid and spindle cells or to a spindle patt ern . Th e nuclei were large and euchromatic, especially in the epithelioid cells. Several tum ors had mod erate cellular pleom orphi sm and binucleate cells. Mitot ic activi ty was generally low (less than l/h igh-powered field), but was readily detected (I-2/h igh-powered field) in bleached sections of four cases. Melanin pigmentat ion varied from mild to heavy. Melanoph ages were admixed with the tum or cells or in the adjace nt tissue. Followup information was obt ained on 15/1 8 horses and revealed that 14/1 5 horses were free of recurren ce following excision. One neoplasm, that was poorl y demarcated and had a spindle cell pattern, was not completely resected and continued to grow. Th ese melanocytic tum ors in young horses are distinct from melanomas in aged horses in their location, epithelial involvement, and age of horses affected. T he major ity of these tum ors appear to be benign and share features of melanocytic nevi of hum an beings.

We studied the effects of maternal exposure to endotoxin on pregnancy outcome, stimulation of the hypothalamo-hypophyseal-adrenal axes (HHAA) of ewes and their fetuses, and maternal production of tumor necrosis factor alpha (TNF alpha), a central mediator in the pathogenesis of bacterial endotoxemia. Either endotoxin (lipopolysaccharide, LPS) from Salmonella typhimurium or saline was administered to pregnant sheep (n = 10) at 137.6 +/- 3.5 days gestational age by slow i.v. infusion at 1 microgram.kg-1 total dose over a 3-h period. Fetuses of ewes treated with LPS became hypoxemic by 2.5 h after initiation of LPS infusion. Maternal ACTH increased and peaked during LPS administration to levels approximately 10-fold greater in treated than in control ewes. In contrast, fetal ACTH levels were maximum at 6-12 h. Maternal and fetal cortisol levels were significantly different from control levels by 1 and 12 h, respectively. Maternal plasma TNF alpha peaked (6-7-fold over baseline) at 1-2 h after initiation of LPS administration and steadily declined over the following 48 h. Four of 5 treated ewes either delivered or their fetuses died within 28 h. In summary, infusion of LPS caused fetal hypoxemia and stimulated both fetal and maternal HHAA followed by preterm labor by 28 h after infusion in 4 of 5 ewes. Three of the fetuses died in utero. Maternal plasma TNF alpha rose rapidly, but the specific role it may play in initiation of preterm labor remains to be elucidated.