CHRONOIMMUNOHISTOCHEMICAL LOCALIZATION OF EPIDERMAL GROWTH-FACTOR IN THE SUBMANDIBULAR-GLAND OF MALE-RATS

Chronobiological oscillation was established for epidermal growth fact or (r-EGF) in granular convoluted tubule (GCT) cells of the male rat s ubmandibular gland (SMG) using immunohistochemistry. The high amplitud e oscillation with a peak at 9 p.m. and low amplitude oscillation duri ng the day time was noted. The distribution pattern of the r-EGF in th e GCT segment was time-dependent, as it was seen at 3 p.m. when many c ells with r-EGF staining were detectable. The higher reactivity during the activity phase of the rats may correlate with the intracellular b iosynthesis of r-EGF required for cell proliferation and maintenance o f ductal integrity. The chronobiological oscillation pattern of r-EGF seems to be important for the maintenance of ductal integrity and woun d healing.