Abstract: Light exposure during later embryonic development has much effect on the postnatal ability of learning and memory. In the present study, Immunohistochemical technique was used to detect and compare NCAM express in HV of embryonic days E17 to E21 eggs, which was dark reared, light reared or normal reared. The NCAM express significant high in light reared and normal reared eggs at embryonic day E20. During all the embryonic days E17 to E21, the NCAM level was very low in dark reared eggs. All this suggested that the NCAM, which regulated by light exposure, might be involved in post hatch learning and memory behaviour.

Key words: chick, embryonic development, neural cell adhesion molecules