Observations on degenerative changes of Purkinje cells during early development in mice and in normal and otocyst-deprived chickens.

The cerebellar noduli of 18 neonatal mice and 13 young chickens were studied by light and electron microscopy. Beginning with postnatal day 10 in mice and incubation day 17 in chickens some Purkinje cells of the nodulus show degenerative changes. The nuclei and cytoplasm of these cells are darker than the neighbouring tissue due to an accumulation of large amounts of ribosomelike particles and an increased stainability of the cytoplasm. Mitochondria and endoplasmic reticulum undergo a moderate swelling, the Golgi apparatus hypertrophies whereas the somata and nuclei atrophy. The percentage of degenerating Purkinje cells reaches a peak of about 45% around postnatal day 14 in mice and the 4th day after hatching in chickens. In 26 otocyst-deprived chickens a smaller proportion of Purkinje cells with degenerative changes is found. The way in which the otocyst removal influences the neonatal Purkinje cell degeneration is not clear.