[Morphological study of congenital osteopetrosis in op rats].

Osteopetrosis appears spontaneously on the "op" rat (Fatty/ORL). At the confirmed stage, description of histologic lesions is made. The attention is attracted by an endocavitary tissue observed at later stage of disease. This one does not seem to be the result of a metaplasia but rather the image of a persistent osteoblastic activity.