Abstract
1. The development of specific and nonspecific cholinesterase (ChE) has been studied manometorically in brain and liver of the human fetus and the chick as their specific sub-strates, using Acetylcholine, Acetyl-β-Methylcholine and Benzoylcholine.
2. Specific ChE activity increased during the antenatal development in the human fetus, however, it decreased during the postnatal development in the chick brain.
3. Nonspecific ChE activity increased during the antenatal development in the human fetus and the postnatal development in the chick liver.
4. These two enzymes were completely different in character, and the pattern of their development was also quite different.
