ULTRASTRUCTURAL MORPHOMETRY OF PAROTID ACINAR-CELLS FOLLOWING FRACTIONATED-IRRADIATION

The aim of this study was to evaluate the long term effects on the ult rastructure of parotid glands after fractionated irradiation. The meth od implemented involved 5 x 6 Gy and 5 x 8 Gy, Monday to Friday 6 MV p hotons. By unilateral irradiation, the contralateral parotid gland ser ved as a control. Although irradiation diminished the acinar cell dens ity in Light microscopic sections from 75 to 32% after 5 x 8 Gy of irr adiation, ultrastructural morphometry could not detect any statistical ly significant differences in acinar cell size, nuclear size, nuclear density, granule area, mean granule size, or granule density. In gener al, greater differences were seen between rats receiving 30 or 40 Gy, on both the irradiated and the control side, than between the irradiat ed side and the control side. This was interpreted as due to differenc es in the nutritional state of the animals. This analysis concluded th at individual acinar cells that survive irradiation seem not to be dam aged in the long term when evaluated at the ultrastructural level. The study further stresses the importance of adequate sampling sizes and the use of adequate controls. (C) 1997 Elsevier Science Ltd. All right s reserved.