A spontaneous thymic carcinosarcoma in a young Sprague Dawley rat

We encountered a case of spontaneous thymic carcinosarcoma in a young Crl:CD (Sprague Dawley) rat. Grossly, a white multinodular mass replaced the thymus in the thoracic cavity. Histologically, multiple nodules were separated by fibrous stroma, and each nodule included isolated regions that were composed of epithelial or non-epithelial tumor cells. The epithelial tumor cells were relatively large and round to polygonal cells with large nuclei and weakly eosinophilic cytoplasm. These cells were cytokeratin-positive and vimentin-negative. These cells infiltrated the lungs. The non-epithelial tumor cells were poorly differentiated, small, round to spindle-shaped cells with small nuclei and basophilic cytoplasm. These cells were vimentin-positive and mostly cytokeratin-negative. Many islands of cartilage were observed near non-epithelial cells. Based on these findings, the tumor was diagnosed as a primary thymic carcinosarcoma consisting of a malignant thymoma composed of epithelial tumor cells and a mesenchymal chondrosarcoma composed of non-epithelial tumor cells.     

Expression patterns of acidic and basic fibroblast growth factor in loach fish embryos

Heparin-binding fractions were taken from the heparin sepharose columns on which extracts of loach fish (Misgurnus anguillicaudatus) embryos from blastula, gastrula, 4–8 and 12–16 somites stages were applied. These heparin-binding fractions, except the fraction derived from 12–16 somite embryos, showed potent mitogenic activity on fibroblast-like cells derived from caudal fin blastema of goldfish. Western blot analysis of these heparin-binding fractions was carried out using monoclonal antibodies against human acidic and basic fibroblast growth factors (FGF-1 and-2). An immunoreactive FGF-1 band at 16 kD was detected in the heparin-binding fraction derived from embryos in each stage of blastula, gastrula and 4–8 somites. An immunoreactive FGF-2 band at 17 kDa was detected exclusively in the heparin-binding fraction derived from 4–8 somite embryos. In the heparin-binding fraction derived from 12–16 somite embryos neither immunoreactive FGF-1 nor-2 member band was detectable.