ALKALINE PHOSPHATASE IN THE NORMAL AND EXPLANTED EMBRYONIC DUODENUM

Abstract

Duodenal loops were excised from 8 twelve day fowl embryos, fixed in alcohol and serial sections cut transversely. Transections of the distal and proximal limbs of the loops in each section were treated by the Gomori procedure for alkaline phosphatase. The enzyme appears in the free borders of the epithelial cells along a developmental gradient; it appears first in the distal limb, then spreads along the proximal limb. Initially, it is demonstrable in foci scattered around the perimeter of the gut which became confluent later. Explants were prepared from the proximal and distal limbs of the duodena of 12 day embryos; after 4 days in vitro, the explants were fixed in alcohol and the distribution of enzyme in the free borders of the epithelial cells compared with control samples. Enzyme became demonstrable in a proportion of explants from proximal loops shown to be negative for border enzyme prior to explantation. It was concluded that the enzyme in the free border was formed in vitro.