Laminar Formation Research Articles

TOXIC EFFECTS OF KAINIC ACID ON MOUSE CEREBELLUM IN TISSUE CULTURE

Cultures of mouse cerebellum were exposed for various intervals after explantation to kainic acid, a glutamic acid analog. Purkinje cells and intracerebellar nucleus neurons were destroyed and cortical laminar formation was inhibited by exposure to kainic acid, while granule cells were relatively spared. Prolonged kainate treatment also reduced the granule cell population. The destructive effects of kainic acid were evident upon exposure of Purkinje cells prior to the development of parallel fiber-Purkinje cell synapses, the neurotransmitter for which is believed to be glutamic acid. Glutamate application to intracerebellar nucleus neurons in vitro did not evoke extracellularly recorded excitatory effects, suggesting that these kainate-sensitive neurons do not have significant numbers of glutamate receptors. The combination of these observations suggests that neuronal toxic effects of kainic acid are not exclusively mediated by action on glutamate receptors, but involve other, less specific mechanisms as well.

Certain characteristics and nuclear lesions in golden hamster melanoma cultures.

A study of the cytological and ultrastructural characteristics, chromosomal value and tumorigenesis of a cultivated golden hamster (Mesocricetus auratus) malignant melanoma was made. Four kinds of cells were observed in the cultures: melanocytes, fusiform cells and two forms of macrophages. Electron microscope observations showed very irregular nuclei with intranuclear lesions, in a type of ring‐like bodies. Vast Golgi zones with melanin formation were seen in the cytoplasm. The melanosomes presented a laminar formation. Extracellular virus‐like particles, 80 mμ in diameter, were observed occasionally. The modal value of chromosome numbers was 44 and they ranged from 42 to 270. When inoculated in hamsters, as small as 500 cells/ml developed tumors in 44–60 days with metastases which retained the property to produce melanin. The significance of the nuclear lesions and virus‐like particles in the golden hamster melanoma cells remain open for discussion.

Observations on the electron microscopic structure of insect muscle

Four electron micrographs are reproduced. The longitudinal section of the wing muscle of the house-fly shows the absence of the series elastic component and of the A and I bands. The possible bearing on the genesis of these bands is discussed. Mitochondria of the wing muscle of the bumble-bee show a tubular inner structure, while the mitochondria of the leg muscle show laminar formations.