Butyrylcholinesterase from intestinal epithelial cells of quail, chick and duck: a comparative study during development.
1. Epithelial cells of avian intestine express non-specific cholinesterase (butyrylcholinesterase, BuChE) activity both in the embryo and adult animal. 2. Quail, duck and chick exhibit increased BuChE activity during the late embryonic period followed by decreased activity. The minimum value is reached after hatching at day 1 in quail, day 4 in chick and day 6 in duck. 3. The three species display marked sex-related differences mainly during the peri-hatching period. BuChE activity is higher in females than in males. 4. The three globular forms, G1, G2 and G4, are detected during the last days of embryonic development. After hatching, changes in the relative amounts of these forms are related to the disappearance of G2 and the gradual decrease of G4. In adult quail and duck, G4 is not detected and BuChE activity corresponds only to the G1 form. 5. The changes in BuChE activity and distribution of the molecular forms occur in a similar manner in all three species although the embryonic periods differ notably, suggesting that hormonal factors secreted during this period and involved in the preparation of hatching may regulate BuChE activity.