Macrophages and apoptosis in the stellate reticulum of the rat enamel organ

Tooth germs of upper first molars of 1, 3, and 5-d-old rats, fixed in forma ldehyde, were stained for the detection of apoptosis by the TUNEL method, a nd by the ate-dye method for the demonstration of acid phosphatase. For con ventional light and electron microscopy the specimens were fixed in glutara ldehyde-formaldehyde and embedded in glycol methacrylate and Araldite. Resu lts showed that macrophages, present in the stellate reticulum, contained b asophilic bodies and TUNEL-positive globules, i.e. apoptotic bodies, in the ir interior. Macrophages also possessed strong acid phosphatase activity. E lectron microscopy showed the presence of large vacuoles inside the macroph ages containing dense fragmented material. Taken together these results sug gest that the intra-epithelial macrophages of the stellate reticulum engulf apoptotic bodies.