Le développement de l' activité des estérases carboxyliques et de la phosphatase alcaline dans l' oesophage,le réseau,le rumen et le f euillet du boeuf1

The development of carboxylic esterases and alkaline phosphatase activity in the bovine forestomachs and esophagus The reticulum, the rumen, the omasum and the esophagus of 8 adult cattle, 6 veal calves, one four-day-old calf and 4 fetuses were examined for esterase and alkaline phosphatase activity. The localization and the intensity of these enzymes in the proventricular compartments are age-related. In the fetuses and the four-day-old calf the esterases are found only in the deeper epithelial cell layers, whereas in the veal calves and in the adults the horny and the transitional cell layer become strongly positive. Alkaline phosphatase is not present in the epithelium of the fetuses. A reaction band of this enzyme occurs at the level of the stratum transitionale in the four-day-old calf. In the adults the upper cells of the stratum spinosum and all the cells of the strata transitionale and corneum are positive. The enzyme activity in the esophagus is very slightly agerelated. The esterases are only found in the deeper epithelial layers, and alkaline phosphatase does not appear in the epithelium. The activity and the localization of these enzymes may be related to the keratinization and especially in the proventricular compartments of the adult, also to the absorption.