Cell Proliferation during Bud Formation of the Quail Uropygial Gland

A localized increase of labeling index (L.I.) was observed in bud-forming epithelium of the uropygial gland of the Japanese quail embryo through computer-aided analysis. At day 10 glandular buds are not yet formed anywhere in the epithelium and the distribution of proliferative activity in the epithelium is not differential. On the following day the peripheral buds are being formed at the externo-lateral end of the basal luminal epithelium, L.I. increases locally in these buds. At day 12 a localized increase of L.I. takes place also at the median end; extremely high labeling indices are seen at the tip of the peripheral buds and developing central buds.