Early lesion of N-nitroso-N-ethylurea-induced hamster neurofibromatosis model

To investigate histogenesis of neurofibroma, early lesions of N-nitroso-N-ethylurea-induced neurofibroma of Syrian golden hamsters were examined. The lesions were detectable from 8 weeks of age, and a total of 14 lesions in 9 hamsters from 8 to 12 weeks of age were observed. Most of the lesions were found in the skin; they were also observed in the trigeminal nerve, cervical plexus, and abdominal sympathetic ganglion. Histological examination revealed there were two types of early lesions such as solitary and plexiform types. The former developed in the s.c. or dermal part of the skin and showed invasive growth of the surrounding tissue, while the latter originated from the large nerves such as the trigeminal nerve or cervical plexus. Growth kinetics of the early lesions was quantitated by continuous administration of bromodeoxyuridine and double immunostaining. Using these systems we observed that various kinds of cells had already participated in early lesions and later Schwann cells became a main component of the tumor. The histogenesis of neurofibroma was considered to be complexed by proliferation of several kinds of cell types at the early stage.