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Normal structure and morphological effects of a corticosteroid on the peripatellar synovial membrane of the rat
N Murashige1, T Gotoh, Y Ichikawa
1Department of Anatomy, Nippon Medical School, Tokyo, Japan.
Abstract:
We observed the peripatellar synovial membranes of normal and betamethasone-treated rats with a scanning electron microscope (SEM), light microscope (LM) and transmission electron microscope (TEM). On the basis of SEM findings, the peripatellar synovial membrane is divided into two distinct regions; an upper, smaller, round, non-folded region which is covered with small excrescences, and a lower, larger, horseshoe-shaped region which has numerous folds consisting of cobblestone-like oval cells. These SEM findings were well confirmed by parallel LM and TEM observations of both regions. The synovial membrane of rats treated with intra-articular injections of betamethasone, an anti-inflammatory agent for rheumatoid arthritis, showed cell-sized excrescences on the surface of the non-folded regions. Under LM and TEM, the synovial membrane of treated rats showed an expansion of the intercellular spaces with collagen fibers, swelling of vacuoles in the cytoplasm in the type M synoviocytes, and increases in the number and elongation of microvilli of the type M synoviocytes. These observations suggest that repeated betamethasone injection therapy may result in unnecessary damage to the synovial membrane.
Insights
Betamethasone injections, used for rheumatoid arthritis, may damage the peripatellar synovial membrane. Microscopic analysis revealed cellular changes and tissue damage in treated rat joints, suggesting potential harm from repeated therapy.
Area of Science:
- Histology
- Rheumatology
- Pharmacology
Background:
- The peripatellar synovial membrane's structure is crucial for joint health.
- Betamethasone is an anti-inflammatory corticosteroid commonly used in treating rheumatoid arthritis.
Purpose of the Study:
- To investigate the ultrastructural effects of betamethasone on the peripatellar synovial membrane in rats.
- To evaluate potential damage caused by intra-articular betamethasone injections.
Main Methods:
- Scanning electron microscopy (SEM) was used to examine the surface morphology.
- Light microscopy (LM) and transmission electron microscopy (TEM) were employed for detailed cellular and tissue analysis.
- Normal and betamethasone-treated rat peripatellar synovial membranes were compared.
Main Results:
- SEM revealed distinct regions in normal synovial membranes: a non-folded upper region with excrescences and a folded lower region.
- Betamethasone treatment induced cell-sized excrescences on non-folded regions.
- LM and TEM showed expanded intercellular spaces, collagen fiber presence, vacuolar swelling in synoviocytes, and increased microvilli in treated rats.
Conclusions:
- Repeated intra-articular betamethasone injections can cause significant ultrastructural damage to the peripatellar synovial membrane.
- These findings suggest that betamethasone therapy may lead to detrimental changes in joint tissues.
- Further research is warranted to understand the long-term implications of corticosteroid-induced synovial damage.
