An immunofluorescence study of age-dependent changes in localization of epidermal growth factor in the submandibular salivary glands of mice

Abstract

The presence of EGF in submandibular salivary glands of mice of various ages was demonstrated by an indirect immunofluorescence technique, and adjacent sections of formalinfixed tissue were stained with alcian blue and acid fuchsin to demonstrate the convoluted granular tubules (CGT). The first signs of CGT differentiation were at 15 days, but the CGT cells did not stain positively for EGF. By 20 days, EGF-positive cells appeared in male mice amongst the more prominent CGT cells, but not in female mice until 25 days. In males, there was a rapid development of the EGF-containing CGT system, reaching adult state tubular distribution at 50 days of age. In females at that age, the salivary glands were still immature, and the CGT system was not as well developed at any age as in males even though their CGT cells had bright EGF-positive immunofluorescence similar to males. During salivary gland maturation, EGF was localized in the CGT cells, and closely followed their age-dependent morphodifferentiation. It seems that endogenous EGF production in mice commences at approximately 3 weeks of age.