| Abstract: | Newborn golden hamsters were inoculated subcutaneously with a cell-free filtrate of cultured mouse 3T3 cells infected with murine sarcoma virus-Harvey (MSV-H). An electron microscopical study was made of the lesions that subsequently developed in these hamsters. Two weeks after inoculation, cysts developed eccentrically in the hila of lymph nodes draining the inoculation site. Type H (radial) virus-like particles were seen in the endothelial cells that lined the cysts and in the serous fluid that filled the cysts. During the 3–6 weeks after inoculation, nodules appeared in lymph nodes, subcutaneous and muscle fascia. They were composed of pleomorphic cells that interlocked with each other and resembled the fixed phagocytic histiocytes of normal lymph nodes. The pleomorphic interlocking cells infiltrated and replaced lymph nodes and perinodal tissues. Some lymph nodes were replaced by abnormal mast cells. During the 12–24 weeks after inoculation tumours were found that involved the paws or limb muscles. The predominant cells in these tumours were similar to the pleomorphic interlocking cells seen in early developing lesions. Similar cells were also found in lymph nodes draining the tumours. It is concluded that tumours induced in golden hamsters by MSV-H are mesenchymal tumours of histiocytic origin. |
