A light and electron microscopical study of the nervous tissue of mouse teratomas.

Teratomas are tumours which may arise spontaneously in the testis or ovary or may be induced experimentally by the implantation of young embryos into ectopic sites. In this study the nervous tissue within mouse teratomas was investigated by light and electronmicroscopy. Characteristic neuroepithelial tubules, neurons, glia and neuropil were recognized and showed no ultrastructural abnormality apart from collagenous infiltration. Synapses were frequently observed. However, other features of mature C.N.S. tissue including myelin and complex synaptic configurations were never seen, and it was not possible to recognize distinct classes of neurons, or organizations of cells and processes which characterized specific regions of the C.N.S. The limited differentiation of the nervous tissue of teratomas is discussed with reference to the normal development of C.N.A. in vivo and in vitro. The presence of synapses in the nervous tissue of teratomas is interpreted as a reflection of an intrinsic tendency of neuronal processes to form these specialized contacts even under conditions which prevent the development of certain other characteristics of nervous tissue.