The objective of the research was to examine the effects of thymus preparations on the histological structure of the spongy part of the mandibular alveolar bone in rats with artificially induced osteoporosis during the intensive growth, development and mineralization of the experimental animals' bones.
White female Wisstar rats were continuosly administered corticopreparations over a 12-week period according to a defined scheme. On the expiry of this period a part of the experimental group of animals was sacrificed, while the remaining part was treated with thymus preparations for another three weeks, after which period they were sacrificed, too. Decalcified samples of the mandible were analyzed at the vestibular-oral section in the region extending from the medial line to the mental foramen, colored by the HE method and analyzed by optical microscopy.
The following changes have been registered as a consequence of the activity of corticopreparations on the histological structure of the mandibular alveolar bone in rats: thinned and lessened number of the spongy bone trabeculae and increased marrow spaces. This indicates that the bone is not productively active and that there is no new bone formation - the bone is "dormant".
Thymus preparations lead to the recovery of the alveolar bone. The metabolism of the spongy bone of the experimental animals is more intense; hence, thymus preparations stimulate osteogenesis and lead to bone tissue remodeling upon termination of the corticotherapy. The recovery of the bone tissue resulting from the influence of thymus preparations is microscopically registered as follows: the trabeculae have their usual appearance, number and size, the marrow spaces have normal dimensions, occurrence of rare cement lines is registerd.
In the conclusion it is emphasized that thymus preparations stimulate bone formation, i.e. osteogenesis, lead to bone tissue remodeling and result in the prevalence of anabolic over catabolic processes, which is of serious interest for the further medical and pharmacological research. (Acta Stom Naissi 1999;16:21-23)

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