Poly-and perfluoroalkyl substances (PFAS) are chemically and thermally stable, hydrophobic, lipophobic compounds used in stain repellants and water and oil surfactants, and associated with immunosuppression and peroxisome proliferator activity. Perfluoro-n-decanoic acid (PFDA, (CF 3 (CF 2 ) 8 COOH), a fluorinated straight chain fatty acid compound, is reported to induce thymic atrophy and reversible bone marrow hypocellularity in rodent models. The objective of this study was to assess potential immunotoxicity of PFDA, due to its structural similarity to other immunosuppressive PFASs. Female Harlan Sprague-Dawley rats were exposed to 0-2.0 mg PFDA/kg by oral gavage daily for 28 d. Female B 6 C 3 F 1 /N mice were exposed once/week to 0-5.0 mg PFDA/kg by gavage for 4 weeks. Animals were evaluated for effects on immune cell populations in spleen and bone marrow, and innate, humoral-, and cell-mediated immunity. Mice were also evaluated for resistance to Influenza virus. Treatment-related hepatocyte necrosis and hepatomegaly were observed in rats treated with 0.5 mg PFDA/kg/d. In mice, hepatomegaly (26-89%) was observed following exposure to !0.625 mg PFDA/kg/week, while splenic atrophy (20%) was observed at 5.0 mg PFDA/kg/week. At 5.0 mg PFDA/kg/week, total spleen cells, and Ig þ and NK þ cells were decreased (17.6-27%). At ! 1.25 mg PFDA/kg/week the numbers of splenic CD3 þ , CD4 þ , CD8 þ , and Mac3 þ cells were decreased (10.5-39%). No changes were observed in leukocyte subpopulations in PFDA-exposed rats. Phagocytosis by fixed-tissue macrophages was decreased in liver (specific activity, 24-39%) at !0.25 mg PFDA/kg/d in rats. PFDA-induced effects on humoral-and cell-mediated immunity, host resistance, and bone marrow progenitor cells were limited. These data suggest that exposure to PFDA may induce adverse effects in rat liver in a manner consistent with the PFAS class, and may also alter the balance of immune cell populations in lymphoid tissues in mice.ARTICLE HISTORY

Identifying environmental exposures that cause adverse mammary gland outcomes in rodents is a first step in disease prevention in humans and domestic pets. ‘Whole mounts’ are an easy and inexpensive tissue preparation method that can elucidate typical or abnormal mammary gland morphology in rodent studies. Here we propose procedures to facilitate the use of whole mounts for histological identification of grossly noted tissue alterations. We noted lesions in mammary whole mounts from 14 month old CD-1 mice that were not found in the contralateral gland hematoxylin and eosin (H&E)-stained section. Whole mounts were removed from the slide and carefully processed to produce high quality histological sections that mirrored the quality of the original H&E-stained section in order to properly diagnose the unidentified gross abnormalities. Incorporation of this method into testing protocols which focus on low-dose human relevant chemicals and endocrine disruptors will increase the chances of identifying lesions in the gland and reduce the risk of false negative findings. This method can be especially invaluable when lesions are not always palpable during the course of the study or visible at necropsy, or when a single cross-section of the mammary gland is otherwise used for detecting lesions.

The 2016 annual National Toxicology Program (NTP) Satellite Symposium, entitled “Pathology Potpourri” was held in San Diego, California, at the Society of Toxicologic Pathology’s (STP) 35th annual meeting. The goal of this symposium was to present and discuss challenging diagnostic pathology and/or nomenclature issues. This article presents summaries of the speakers’ talks, along with select images that were used by the audience for voting and discussion. Some lesions and topics covered during the symposium included malignant glioma and histiocytic sarcoma in the rodent brain; a new statistical method designed for histopathology data evaluation; uterine stromal/glandular polyp in a rat; malignant plasma cell tumor in a mouse brain; Schwann cell proliferative lesions in rat hearts; axillary schwannoma in a cat; necrosis and granulomatous inflammation in a rat brain; adenoma/carcinoma in a rat adrenal gland; hepatocyte maturation defect and liver/spleen hematopoietic defects in an embryonic mouse; distinguishing malignant glioma, malignant mixed glioma and malignant oligodendroglioma in the rat; comparison of mammary gland whole mounts and histopathology from mice; and discussion of the International Harmonization of Nomenclature and Diagnostic Criteria (INHAND) collaborations.

No abstract