Cytochemical localisation of 5'-nucleotidase in amoeboid microglial cells in postnatal rats

The activity of the enzyme 5'-nucleotidase has been studied in postnatal rats. In 5 days old rats, under the light microscope, round amoeboid microglial cells were stained for the enzyme. The cytoplasm was stained dark brown, with a clear nucleus. In older rats, the reactive amoeboid microglial cells assumed an oval or flattened form. In the electron microscope, in 5 days old rat, reaction product was deposited at various sites in the cytoplasm of the amoeboid microglial cells: over lysosomes in subplasmalemmal vacuoles as well as in saccules of the Golgi apparatus. In older rats the cells showed reaction over the lysosomes. The cells became oval and elongated.