Appearance of Enzyme Activity During Metaplastic Changes of the Chick Embryo Chorioallantoic Membrane 1

Abstract

Summary

Chick embryo chorion undergoes a keratogenous metaplasia when the egg is fenestrated and the chorioallantois exposed to air. Normal chorion contains little histo-chemically demonstrable esterase or acid phosphatase. By contrast, the chorion of fenestrated eggs undergoes a squamous metaplasia and keratinization which is accompanied by a dramatic increase in activity of both enzymes. In this respect, the chorion is similar to epidermis in which esterase and acid phosphatase also increase strikingly prior to keratinization. Unlike the epidermis, these chorionic enzymes are not affected by prior hypophysectomy.