Magnetic resonance imaging of the temporomandibular joint in the rat compared with low-powered light microscopy.

OBJECTIVE: High magnetic field magnetic resonance imaging (MRI) was applied to the temporomandibular joint (TMJ) in the rat. The purpose of this study was the depiction of the internal structure of the TMJ, including the articular disc, articular cartilage, and the upper and lower joint cavities. We also proposed MRI settings and slices suitable for imaging the TMJ in the rat. METHODS: Temporomandibular joints from one female and eight male Sprague Dawley rats (5-8 weeks old) and four male Wistar-Hamamatsu rats (7-8 weeks old) were used. Using scout images, the horizontal plane was defined as being parallel to the body of the basisphenoid bone underneath the base of the brain. The coronal plane was defined as a slice vertical to the horizontal plane and vertical to the longitudinal fissure of the cerebrum. The sagittal plane was defined as a slice vertical to the horizontal plane and parallel to the longitudinal fissure of the cerebrum. RESULTS: T(1)-weighted MR images with a spatial resolution of 75 µm were obtained for 5 min. The temporal bone and mandibular condyle were depicted as lower signal intensity images and the articular disc was depicted as an intermediate signal intensity image. In accordance with Gd-DTPA-enhanced MR or T(2)-weighted MR images, the articular disc, articular cartilage, and the upper and lower joint cavities could be assigned clearly. CONCLUSION: These MRI findings closely agreed with those observed with haematoxylin-eosin staining under light microscopy, suggesting that MRI is a useful method for analyzing the complex structure of the TMJ in the rat.

Effects of dibromoacetic acid on murine spermatozoa and testis.

Background and Aims: Bromoacetic acids are a by-product of water ozonation and dibromoacetic acid (DBAA) in particular, which is a by-product of disinfection, inhibits male reproductive functions. In order to understand its effects, the spermatozoa and testes of mice were exposed to DBAA. Methods: Twelve-week-old ICR mice were exposed to 10 p.p.m. DBAA. They were examined in regards to effects on the weights of body, testis and epididymis, the histological changes of tesits and the protein expression in testis. Results: Neither the bodyweight nor the weights of the testis and epididymis of the exposed mice was affected, but approximately 13% of spermatozoa obtained from the cauda epididymis were motile with a drop-shaped head, and structures resembling residual bodies were found in the testis. Moreover, the expression of two testis proteins was changed by exposure to DBAA. Conclusions: It was likely that DBAA inhibited male reproductive functions by disturbance of spermatogenesis via change of protein expression. (Reprod Med Biol 2004; 3: 85-93).