Towards a far more steady idea of maternity micronutrient fat burning capacity.
 Histopathological information about spontaneous lesions in aged Hannover Wistar rats is limited. In this study, we describe spontaneous lesions found in 39 male RccHanWIST rats used as a control in a carcinogenicity study. Neoplastic lesions were frequently seen in the endocrine system, such as pituitary adenomas in the pars distalis. This strain exhibited a high incidence of thymoma (10.3%), compared to other strains. We encountered an oligodendroglioma, a pituitary adenoma of the pars intermedia, and a prostate adenocarcinoma, which are comparatively rare in rats. While the variety and incidence of non-neoplastic lesions were similar to those in other strains, several interesting lesions occurred with relatively high incidence, including "harderianization" of the extraorbital lacrimal gland, common bile duct ectasia, and hyperplasia of pulmonary endocrine cells in the lung. Furthermore, comparative analyses demonstrated that the severity of chronic progressive nephropathy and murine progressive cardiomyopathy in RccHanWIST rats was less than that in F344 rats. ©2020 The Japanese Society of Toxicologic Pathology.Pathological evaluation of juvenile toxicity studies requires the understanding of normal tissue development at different ages. Here, we report the morphological features of the neonatal mouse intestine, focusing on crypt fission. Postnatal day (PND) 7 and 14 mice showed fewer crypts and less mature epithelial morphology compared to PND 21 and 28. Crypt fission occurred in three stages 1) flattening of the crypt base into a skirt shape, 2) penetration of myofibroblasts into the crypt base center, and 3) complete separation of a single crypt into two daughter crypts. The ratio of crypt fission to total number of crypts was the highest at PND 14 and 7 in the jejunum and colon, respectively. Crypt fission, a key phenomenon for balance or imbalance in epithelial cell hierarchy, including stem and differentiated cells, is related to tissue injury repair and tumorigenesis. Therefore, examining crypt fission can provide valuable insights into current conditions of intestine.  https://www.selleckchem.com/mTOR.html  ©2020 The Japanese Society of Toxicologic Pathology.A rare spontaneous hepatic leiomyosarcoma with osteosarcomatous differentiation was observed in a female beagle dog and its morphological and immunohistochemical characteristics were examined. Upon necropsy, an endoceliac mass originating from the liver was detected, which was composed of hematoid fluid-filled cysts and white to grayish solid tissue. There were no macroscopic findings in other organ systems. Histopathologically, the hepatic mass consisted of two different mesenchymal components. One form was spindle cells arranged in interlacing fascicles immunohistochemically positive for smooth muscle actin (SMA) and smoothelin, indicating leiomyosarcomatous differentiation. The other form was composed of short spindle cells positive for S-100 and was producing various amounts of eosinophilic osteoid and trabecula-like matrices positive for osteocalcin, indicating osteosarcomatous differentiation. In addition, invasive growth in the hepatic parenchyma and cell atypia were observed. Based on these findings, the mass was diagnosed as hepatic leiomyosarcoma with osteosarcomatous differentiation (malignant mesenchymoma), which might be derived from undifferentiated mesenchymal cells. ©2020 The Japanese Society of Toxicologic Pathology.This case report describes angiomatous hyperplasia in the heart which is an unusual location in a young male Sprague-Dawley rat in a short-term toxicity study. Histologically, the lesion was characterized by blood-filled vascular channels of variable diameter lined by a thin wall and surrounded by a thin fibrous stroma and minimal lympho-plasmacytic and neutrophilic infiltrate in the apex of the heart. Immunohistopathology using CD31 confirmed the blood vessel origin, and using Ki67 confirmed low cell-proliferative activity in the vascular endothelial cells. To the authors' knowledge, this is the first report of spontaneous angiomatous hyperplasia in the heart of a young rat. ©2020 The Japanese Society of Toxicologic Pathology.A smooth white focus was macroscopically observed in the right ventricular endocardium in a 15-month-old male beagle from a 4-week oral gavage toxicity study. This lesion likely arose from myofibroblasts and was diagnosed as subendocardial nodular proliferation of myofibroblasts. This lesion was observed only in one animal in a low dose group and was an incidental finding. Histopathologically, the well-demarcated nodule comprised abundant collagen containing spindle cells arranged in intermediate to long streams and formed broad interlacing fascicles. The spindle cells had an indistinct cell border with round to elongated hyperchromatic nuclei or nuclei with finely stippled chromatin and indistinct nucleoli. Furthermore, these cells were weakly positive for S100 and positive for α-smooth muscle actin, calponin, and vimentin. Based on the histological features, the proliferating spindle cells resembled phenotypes of smooth muscles or myofibroblasts. However, the proliferating cells lacked well-differentiated smooth muscle cells, cigar-shaped nuclei, and well-developed reticulin fibers outlining individual cells. This study describes the morphological characteristics of an endocardial proliferative lesion in the right ventricle of a beagle. ©2020 The Japanese Society of Toxicologic Pathology.A 40-week-old male spontaneous diabetic Torii rat, an animal model of type 2 diabetes mellitus, was found to have marked urinary calculi with hematuria in the urinary bladder on necropsy. Histological findings in the urinary bladder included a papillary growth pattern with a fibrovascular stroma without atypia. Fine granular materials in the bladder lumen were positive for Von Kossa staining but negative for periodic acid-Schiff or Gram staining, indicating no apparent bacterial infection in the urinary bladder. Scanning electron microscopy revealed that the urinary calculi were magnesium ammonium phosphate crystals (struvite). On the basis of the results, the lesion was diagnosed as urothelial hyperplasia with calculi (papillomatosis).  https://www.selleckchem.com/mTOR.html  Chronic inciting stimuli by struvite crystals were considered the primary cause of the bladder findings. ©2020 The Japanese Society of Toxicologic Pathology.