RETINOID DYNAMICS IN CHICKEN EYE DURING PRENATAL AND POSTNATAL DEVELOPMENT

Changes in the steady state level of retinols, retinaldehydes and reti nyl esters in the trans and 11-cis forms and trans retinoic acid were measured in whole chicken eye during development from day 6 in ovo to day 3 post-hatch. These retinoids, quantified by different HPLC system s, were detected in this time sequence: trans-retinol and trans-retiny l eaters in the first week in ovo, 11-cis-retinol in the second week. The highest level of 11-cis-retinaldehyde and 11-cis-retinyl esters wa s reached at the end of development in ovo; however, their levels incr eased further after hatching. The retinoic acid level decreased at the end of the first week, rising again at the end of the second week. Th e enzyme activities involved in the metabolism of these retinoids-acyl -CoA: retinol acyltransferase, trans-retinol dehydrogenase, 11-cis-ret inol dehydrogenase, trans-retinyl eater hydrolase and trans: 11-cis-re tinol isomerase were also estimated and they were detectable already i n the first week of development in ovo. At day 6 of the biosynthesis o f retinoic acid by the retinaldehyde dehydrogenase activity from retin a cytosol was also shown.