Acetylcholinesterase Activity in the Optic Lobes of Chicks at Hatching

ACETYLCHOLINESTERASE (AChE) activity is used as an indicator of the development of function in the central nervous system (CNS). In the spinal cord of the chick embryo, AChE reaches a peak activity after 2 weeks of incubation and corresponds with the functional development of the chick spinal cord (ref. 1 and Turbow, M. M., and Burkhalter, A., in preparation). For example, chick embryos show full flexor-extensor seizures elicited by direct stimulation of the spinal cord at 14 days of incubation 1 . Observations by Lindeman 2 have shown that the pupillary constrictor reflex can first be elicited by stimulating the chick retina at 18 days of incubation and corresponds with a sharp rise in ACh content and an increase in AChE activity. Peters et al. 3 have found that the electrical activity in the optic lobes is sharply increased at about 18 days of incubation, a time at which AChE activity begins to rise sharply. AChE activity has also been correlated with the functional and morphological development of the synapse in the spinal cord of the rat foetus 4,5 .