THE NEUROPATHOLOGY OF THE FATTY LIVER AND KIDNEY SYNDROME OF CHICKS

Sudanophilic lipid, probably triglyceride, was present in perivascular locations and in the cytoplasm of small cells in the brains of chickens with FLKS. The lipid was most consistently observed and was most abundant in the optic tectum and the cerebellum but in severely affected cases many regions of the central nervous system were implicated. The medulla oblongata and spinal cord were least often involved. The grey matter was predominantly affected. Degeneration, demyelination and gliosis were absent and there was no histological evidence of reduced amounts of glycogen in the lumbar glycogen body. Neurons and satellite cells of the spinal ganglia and autonomic plexuses, the epithelium of the choroid plexus and the cells of the epiphysis cerebri contained abnormal accumulations of lipid. Electron microscopy revealed that the greater part of the lipid was in the perikaryon and processes, particularly the endfeet, of astrocytes. Some lipid was also present in ganglionic neurons. Apart from the lipid droplets, the astrocytes and all other cells observed at the ultrastructural level, were morphologically normal.     

THE DISTRIBUTION AND ROLE OF MICROTUBULES AND FILAMENTS IN THE NEOPLASTIC ASTROCYTES OF EXPERIMENTAL GLIOMAS

The distribution and role of microtubules and filaments in the neoplastic astrocytes of experimental gliomas Neoplasms of the nervous system were induced transplacentally by giving N-ethyl-N-nitrosourea (ENU) to pregnant rats on the 15th day of gestation. Astrocytomas and mixed gliomas with a significant astrocytic component were selected in order to study the distribution of microtubules and filaments in neoplastic fibrillary astrocytes. Electron microscopy of these gliomas revealed a population of pleomorphic astrocytes at various stages of differentiation. Poorly differentiated neoplastic astrocytes showed many microtubules but few filaments. In moderately differentiated cells there was a decrease in the number of microtubules with a concurrent increase of filaments. In well differentiated neoplastic astrocytes filaments dominated the cytoplasm forming thick, tightly packed bundles at the periphery of the cells and in the large processes, while occasional microtubules were intermingled with shorter and looser bundles of filaments. Thus, neoplastic fibrillary astrocytes in ENU-induced gliomas simulate the various stages in the differentiation of normal fibrillary astrocytes. This suggests that the ratio of microtubules to filaments may be one of the more discriminating criteria by which the degree of differentiation of neoplastic astrocytes can be established.