Spontaneous B-cell lymphoma in the cranial mediastinal lymph node of an aged male C57BL/6J mouse.

B-cell lymphoma is generally observed in the spleen, mesenteric lymph nodes, and Peyer's patches in aged mice and rarely appears in other organs. Herein, we report a case of spontaneous B-cell lymphoma originating from the cranial mediastinal lymph node in a male 75-week-old C57BL/6J mouse. Macroscopically, a white mass was found at the base of the heart with no connection to the thymus.

Combination of pathological, biochemical and behavioral evaluations for peripheral neurotoxicity assessment in isoniazid-treated rats.

In drug development, assessment of non-clinical peripheral neurotoxicity is important to ensure human safety. Clarifying the pathological features and mechanisms of toxicity enables the management of safety risks in humans by estimating the degree of risk and proposing monitoring strategies. Published guidelines for peripheral neurotoxicity assessment do not provide detailed information on which endpoints should be monitored preferentially and how the results should be integrated and discussed.

Karnovsky's fixative prevents artifacts appearing as vacuolation derived from tissue processing in kidneys treated with antisense oligonucleotide.

Antisense oligonucleotide (ASO) therapies have been identified as a new treatment modality for intractable diseases. In kidneys treated with ASOs, vacuoles, in addition to basophilic granules, are often observed in the proximal tubules. Some reports have described that these vacuoles are likely to be a secondary phenomenon resulting from the extraction of ASOs during tissue processing.

Spontaneous ovarian choriocarcinoma in a young ICR mouse.

This paper describes the spontaneous ovarian choriocarcinoma observed in a young female Crl:CD1 (ICR) mouse. The mouse was sacrificed at 8 weeks of age after oral administration of a compound for 2 weeks. The left ovary was found to be cystically enlarged with dark red hemorrhaging.

Spontaneous hyaline glomerulopathy in a young Slc:ICR mouse.

Hyaline glomerulopathy is a type of glomerular lesion that occurs in aging mice. Spontaneous hyaline glomerulopathy is rare in young mice. Here, we report spontaneous hyaline glomerulopathy in a young adult (15-week-old) ICR mouse.

Participation of Somatic Stem Cells, Labeled by a Unique Antibody (A3) Recognizing both N-glycan and Peptide, to Hair Follicle Cycle and Cutaneous Wound Healing in Rats.

A monoclonal antibody (A3) was generated by using rat malignant fibrous histiocytoma (MFH) cells as the antigen. Generally, MFH is considered to be a sarcoma derived from undifferentiated mesenchymal cells. Molecular biological analyses using the lysate of rat MFH cells revealed that A3 is a conformation specific antibody recognizing both -glycan and peptide.

Participation of Somatic Stem Cells, Recognized by a Unique A3 Antibody, in Mucosal Epithelial Regeneration in Dextran Sulfate Sodium (DSS)-Induced Rat Colonic Lesions.

A3, generated as a monoclonal antibody against rat malignant fibrous histiocytoma cells, recognizes somatic stem cells in rats. We analyzed the distribution of A3-positive cells in dextran sulfate sodium (DSS)-induced colonic lesions consisting of regenerating mucosa and fibrosis. Male 6-week-old F344 rats were administered 5% DSS in drinking water for 5 to 7 days, and lesions at recovery stage were also examined.

Quantification of histopathological findings using a novel image analysis platform.

Digital pathology, including image analysis and automatic diagnosis of pathological tissue, has been developed remarkably. HALO is an image analysis platform specialized for the study of pathological tissues, which enables tissue segmentation by using artificial intelligence. In this study, we used HALO to quantify various histopathological changes and findings that were difficult to analyze using conventional image processing software.

The localization and distribution of cells labeled by a somatic stem cell-recognizing antibody (A3) in rat colon development; possible presence of a new cell type forming the intestinal stem cell niche.

A3, generated as a monoclonal antibody against rat malignant fibrous histiocytoma (MFH)-derived cloned cells, recognizes somatic stem cells (bone-marrow/hair follicle stem cells). We investigated the distribution of cells immunoreactive to A3 in the developing rat intestine (particularly, the colon), focusing on the ontogenic kinetics of A3-positive cells. In the rat intestine, A3 labeled spindle-shaped stromal cells localized in the submucosa and labeled endothelial cells of capillaries in the lamina propria forming villi in the early development stage.

Unilateral luteoma of the ovary in a pregnant Risso's dolphin (Grampus griseus).

A white, lobular mass was found in the right ovary of a pregnant Risso's dolphin (Grampus griseus) at necropsy. The mass was unilateral and occupied most of the pre-existing ovarian tissue. Histologically, the mass was composed of diffuse sheets of polyhedral cells with abundant eosinophilic cytoplasm and oval nuclei, separated by fibrous connective tissue.