Light and transmission electron microscopy used to study the tissue morphology close to implants.

A methodological study was performed in order to allow the morphological investigation of the interface to titanium bulk implants by light (LM) and transmission electron microscopy (TEM). Titanium implants were removed 3-9 wk after insertion in the knee joints or the abdominal wall of rabbits and rats. After fixation, the implants were either removed before embedding or separated from the surrounding tissue after the embedding of tissue and implant en bloc. While implant removal before embedding often caused minor defects in the interface, separation after embedding left the interface intact. TEM showed a thin layer of amorphous substance separating intact cells and collagen fibrils. No tissue remnants were revealed by scanning electron microscopy (SEM) on the surface of implants separated after embedding. The good preservation of the interface and the possibility to also examine ultrastructurally the intact tissue surrounding bulk implants, including very thin cell layers, make the method useful for biocompatibility studies in vivo.