Pathways of inflammatory cellular exudate through radicular cyst epithelium: a light and scanning electron microscope study.

A feature of radicular cyst histology is the observation that polymorphonuclear leucocytes infiltrate the epithelium whereas chronic inflammatory cells do not and accumulate in the subepithelial connective tissue. Material for the study of this phenomenon consisted of radicular cysts fixed in formol saline. Observation under the SEM indicated that the lumenal surface of the radicular cyst is characterized by numerous interepithelial spaces through which polymorphonuclear cells reach the cyst cavity. The cells on the lumenal surface are associated with interepithelial spaces. Observations of the cut surface indicate that channels occur between epithelial cells through which the polymorphonuclear leucocytes migrate. The channels may also be a pathway for exudates from capillaries to reach the cyst cavity and provide a means for radicular cyst enlargement. Erosions of epithelial cells and features of necrosis of superficial cells were observed. Thus it appears that polymorphonuclear leucocytes migrate through definite channels between epithelial cells in the radicular cyst lining, the chemotactic stimulus being degeneration and breakdown of the superficial epithelial cells.