Long root of deciduous anterior teeth.

A 24-year-old female Japanese patient presented with remarkably long roots of retained deciduous anterior teeth and permanent anterior teeth in the upper and lower jaw. Four lower anterior teeth were extracted for esthetic reasons. The patient had no apparent clinical syndrome related to the teeth or jaw, nor did there appear to be a family history of this condition. The extracted teeth and their lengths were as follows: the lower right deciduous lateral incisor was 25.55 mm long (root length, 18.95 mm); the lower left deciduous lateral incisor was 22.10 mm long (root length, 17.25 mm); the lower right deciduous canine was 27.95 mm long (root length, 20.60 mm); and the lower left deciduous canine was 23.90 mm long (root length, 17.65 mm).

Th1 biased response to a novel Porphyromonas gingivalis protein aggravates bone resorption caused by this oral pathogen.

In previous studies we showed that biasing the immune response to Porphyromonas gingivalis antigens to the Th1 phenotype increases inflammatory bone resorption caused by this organism. Using a T cell screening strategy we identified eight P. gingivalis genes coding for proteins that appear to be involved in T-helper cell responses. In the present study, we characterized the protein encoded by the PG_1841 gene and evaluated its relevance in the bone resorption caused by P. gingivalis because subcutaneous infection of mice with this organism resulted in the induction of Th1 biased response to the recombinant PG1841 antigen molecule. Using an immunization regime that strongly biases toward the Th1 phenotype followed by challenge with P. gingivalis in dental pulp tissue, we demonstrate that mice pre-immunized with rPG1841 developed severe bone loss compared with control immunized mice. Pre-immunization of mice with the antigen using a Th2 biasing regime resulted in no exacerbation of the disease. These results support the notion that selected antigens of P. gingivalis are involved in a biased Th1 host response that leads to the severe bone loss caused by this oral pathogen.

Rare case of the inferior mesenteric artery and the common hepatic artery arising from the superior mesenteric artery.

We found a case in which inferior mesenteric artery and the common hepatic artery arose from the superior mesenteric artery, forming the common hepatomesenteric trunk, during a routine dissection carried out at Iwate Medical University in 2002. This variation is rare, but can be embryonically explained. A change in the positions of the disappearance of the ventral splanchnic arteries and the longitudinal anastomotic channel results in variations in the system of arteries distributed to the digestive organs. In the present case, the longitudinal anastomotic channel between the superior and the inferior mesenteric arteries survived to form the common mesenteric artery, which was joined by the common hepatic artery, forming the common hepatomesenteric trunk.

Comparison of the thickness of basement membranes in various tissues of the rat.

The thicknesses of the lamina lucida and the lamina densa of basement membranes in various kinds of tissues, including the epidermis and mucosal epithelium, and basement membranes adjacent to a Schwann cell, perineurial sheath cell, endothelial cell, pericyte, muscle cell and fat cell, were compared on high-powered transmission electron micrographs. Each tissue and cell possessed a basement membrane with thicknesses of the lamina lucida and lamina densa that were specific to the particular tissue or cell. This indicates that the lamina lucida and lamina densa of the basement membrane of a tissue/cell have a particular constitution. New theories on the molecular constitution between the cell surface and basement membrane may need to be developed.

Abnormal anterior belly of the digastric muscle: a proposal for the classification of abnormalities.

We recognized an abnormal anterior belly of the digastric muscle in an 83-year-old male cadaver. Three muscle bundles were observed on the left anterior belly: (i) attached to the left digastric fossa; (ii) attached to the right digastric fossa; and (ii) attached to the raphe of the mylohyoid muscle. Four muscle bundles were recognized on the right anterior belly: (i) attached to raphe of the mylohyoid muscle; (ii, iii) attached to the exterior surface on the base of the mandible from the raphe of the mylohyoid muscle; and (iv) attached to the interior surface on the base of the mandible from the raphe of the mylohyoid muscle. The raphe of the mylohyoid muscle was curved significantly to right and the four abnormal bundles found on the right anterior belly (see above) were attached to its curved point.

Real electron microscopic images of collagen fibrils in the endoneurium.

Collagen fibrils run in parallel in the endoneurial space, forming fibre bundles. Spaces are evident between these bundles when examined by transmission electron microscopy (TEM). However, the procedures for TEM include chemical fixation, dehydration and embedding, which may cause morphological changes in the specimens. Ultracryo thin sectioning procedures may avoid the artefacts caused by these procedures. An examination of ultrathin frozen sections revealed that the endoneurial space was completely filled with collagen fibrils, with little space between the fibre bundles. These results suggest that the dehydration and/or embedding procedures cause shrinkage of the specimen, resulting in the appearance of a widened space in the endoneurium. Therefore, the widened space between the bundles of collagen fibrils may be a technical artefact.

Measurement of the repeat period of myelin sheath using ultrathin frozen sections.

The myelin sheath of peripheral nerves was observed by transmission electron microscopy (TEM) using plastic-embedded sections and ultrathin frozen sections. Repeat distances of myelin sheaths were measured in high-powered electron micrographs. The ultrathin frozen sections showed a longer repeat distance than the plastic-embedded sections. The ultrathin frozen sections were thought to contain fewer artefacts, as they had not been subject to dehydration and embedding. It is known that broken myelin sheaths are often observed under conventional TEM. It is thought that these procedures cause contraction and partial destruction of the myelin sheath.