The ultrastructure of clinically normal sulcular tissues in the beagle dog

The ultrastructure of clinically normal beagle sulcular epithelium and underlying connective tissue has been studied in order to obtain base line information for comparison with similar studies of overtly inflamed gingiva. Normal sulcular epithelium in the beagle was observed to undergo a cytodifferentiation from typical keralinocytes of the stratum basale and stratum spinosum to flattened superficial cells which contained a relatively prominent endoplasmic reticulum and Golgi system. These cells also contained many dense granules of an unknown function. Narrow intercellular spaces filled with a material of moderate electron density were observed between flattened superficial cells. Moderate numbers of neutrophils were found in the epithelium along with “clear cells” of an unknown type. The underlying connective tissue was characterized by a preponderance of well organized collagen libers and numerous fibroblasts. No unusual findings were noted in either blood vessels or peripheral nerves. Macrophages were prominently located in the lamina propria and in perivascular locations. Lymphocytes, neutrophils and plasma cells were seen in moderate numbers, usually located in the lamina propria portion of the sulcular wall. These cells when present in moderate numbers do not appreciably alter the integrity of the tissues and should be considered as components of a normal defense system.