Degenerating chondrocytes are often localized in the lower hypertrophic and calcifying zone of rat epiphyseal cartilage. The ability of these degenerating chondrocytes to synthesize and secrete sulfated proteoglycans was investigated using the light microscopic radiosulfate labeling method and the high-iron diamine-thiocarbohydrazide-silver proteinate (HID-TCH-SP) method for sulfated complex carbohydrates at the ultrastructural level. At 30 min following intraperitoneal (IP) injection of 35SO4, only intracellular autoradiographic labeling was observed, whereas both intracellular and extracellular radiosulfate labeling was seen at 1 h postinjection. A giadual increase in intracellular and extracellular labeling was seen at 3, 12 and 24h following IP injection of 35SO4. In ultrastructural cytochemical preparations, HID-TCH-SP weakly to moderately stained the chondrocyte Golgi vacuoles or immature and intermediate secretory granules but did not stain Golgi saccules. Mature secretory granules and extracellular matrix granules demonstrated strong staining. These results therefore indicate that proteoglycans are sulfated in the degenerating chondrocyte Golgi vacuoles, packaged in the secretory granules and then released into the extracellular matrix to form matrix granules.

The mode of tooth attachment in the black bass was observed by scanning electron microscopy, stereoscopic microscopy and light microscopy.The black bass had conical teeth on the lower and upper jaws and these teeth had a hinged attachment. The form of attachment between the basal dentin and the pedicle differed between the anterior hinge and the posterior hinge. In the anterior hinge the front portion of the basal dentin was free from the pedicle, which was thickened and rounded like a buttress of bone. However, in the inner part of the anterior hinge and in the posterior hinge, the fibers of the basal dentin were continuous with the pedicle.The fibers of the anterior and the posterior hinge were collagenous, but the degree of contraction differed between the lingual and pulpal sides of the posterior hinge. These differences in the structure of the hinged attachment were adapted to its function.

The fine structure of the junctional epithelium (JE) was studied by electron microscopy using molars of golden hamsters aged 10 days or 5 weeks. The following conclusions were obtained : 1. Primary epithelial attachment (PEA)The oral sulcular epithelium (OSE) adjoins the enamel organ at the top of the JE. Cells of the JE showed the same structure as those of the enamel organ at the pigmentation stage. Secondary epithelial attachment (SEA)In the cells directly connected with the adjoining enamel, the Golgi apparatus was located in the cytoplasm facing the enamel, and the rough endoplasmic reticulum was found in its vicinity. In other words, this cell type showed polarity, as in secretory cells. Cells located over the cells connected with the enamel contained small vacuoles with electron-dense material in the cytoplasm. Cell divisionA large number of mitotic figures were found in the basal layer and cells directly connected with the enamel of the JE, and these were very numerous in the infected JE. This finding was considered to indicate that there is a relationship between the deepening of pockets and bacterial infection.Polymorphonuclear leukocytes (PMN) were found mostly in the intercellular spaces between ameloblasts of the PEA, and in the papillary layer of the PEA. In the SEA, PMN were found mainly in the intercellular spaces between cells connected with the enamel and those of cells containing small vacuoles, as well as in the OSE. Very occasionally, PMN infiltrated the JE through the basal lamina at its apical end.