Cytoplasmic crystalloids in the periodontal tissue of beige mice.

The periodontal tissue of beige mice has been examined by electron microscopy. Specimens of the periodontal tissue from the right mandibular first molars of 10 male beige (bg/bg) and 5 male non-beige (bg/+, controls) mice, were fixed in a mixture of glutaraldehyde and paraformaldehyde, and then decalcified in EDTA. After fixation in osmium tetroxide, the specimens were dehydrated and embedded in epon resin. Ultrathin sections were then stained with uranyl acetate and lead citrate, and observed by electron microscopy. A larger number of cytoplasmic crystalloids were seen in the lysosomes of the histiocytes of the beige mice than in the non-beige mice. These cytoplasmic crystalloids showed striation structures composed of linear densities that were oriented longitudinally, transversely, and obliquely, with about a 4-nm periodicity. The periodontal tissue of the beige mice contained several cells with numerous cytoplasmic crystalloids, whereas there were few cells with fewer crystalloids in the non-beige mice.