Ultrastructural changes in rat-molar cementoblasts after administration of puromycin.

Ultrastructural changes in rat-molar cementoblasts after administration of puromycin were observed. Young Wistar male rats were injected with 200 mg/kg of puromycin dihydrochloride. At 10, 30, 60, and 180 minutes after the injection, the animals were fixed by perfusion with 2.5% glutaraldehyde-2.0% paraformaldehyde. After perfusion, the lower first molars were dissected out of the mandibles, and their cementoblast were observed in an electron microscope. Striking changes were seen in the Golgi apparatus and the rough endoplasmic reticulum after puromycin administration. The Golgi saccules were dilated and devoid of content. Golgi vacuoles and secretion granules were reduced in number. Numerous small, smooth-walled vesicles, 45-70 nm in diameter and a large number of coated vesicles were present in the Golgi area. The rough endoplasmic reticulum showed unusual shapes and arrangement. Ribosomes attached to the reticulum lost polysomal arrangement. These changes progressed following the time elapsed after experiment, and a great number of large vacuoles which contain fine flocculent material came to predominate the supranuclear areas of the cementoblasts.