Abstract:The initial calcification processes inside the po res of porous hydroxyapatite ceramics implanted into the submandibular salivary glands of rats were observed by light -microscopy and by scanning and transmission electron-microscopy at varying int ervals for 10 weeks after implantation .The inorgani c elements inside the pores were examined by line -and surface-analysis with x -ray-d etection energy-dispersive analysis .The porous hydroxyapatite ceramics were encapsulated with a layer of fibrous tissue during the later stages, although during the earlier stages the surr ounding tissues showed inflammatory phenomena .Insid e the pores of the implants , two types of calcification processes were observed. The first type was devoid of cells or any collagen fibrils , whereas in the second type, fibroblast-like cells, whichi nvaded the pores of the implants , and collagen fibrils appeared to be associated with the initial calcification processes .