Studies on experimental malignant nerve sheath tumors maintained in tissue and organ culture systems. I. Light microscopy observations.

Explants from seven nerve sheath tumors (four cranial and three spinal) induced in rats by transplacental ethylnitrosourea were grown on collagen-coated coverslips and in organ culture systems, using sponge foam matrices and Millipore filter platforms. Their sequential morphological features in vitro were compared to those of a human acoustic Schwannoma maintained in similar culture systems. The original experimental tumors were either undifferentiated or poorly malignant Schwannomas. In cultures on collagen-coated coverslips the explants demonstrated cellular features that were considerably more anaplastic than those of the human acoustic Schwannoma. On the other hand, in organ culture systems, in which viable cultures were maintained up to 82 days, many of the experimental tumor explants exhibited progressive differentiaiton, with nuclear palisading, increasing whorl formation and abundant reticulin fibers, and their pattern of histological organization came therefore closely to resemble that of the cultured acoustic Schwannoma. Unlike the latter, however, the cultured experimental tumors infiltrated the sponge foam matrices, a feature that mimicked the invasive character of the original tumors in vivo. Included normal ganglion cells remained demonstrable in the cultures up to 69 in vitro.