RESUMEN
Chick corneas from days 9 through 18 of embryonic development were analyzed for phospholipid and glycolipid content, and for phospholipid and ganglioside classes using chromatographic techniques. Little change in phospholipid headgroup classes was detected during this time span, with the exception of a steady increase in the content of phosphatidylserine from 12 to 18% of the total. Changes in glycolipid content also were observed, with a maximum in the sphingolipid/phospholipid ratio at day 14. This increase was correlated with the appearance of highly sialylated gangliosides at days 14 and 15; these ganglioside species then declined in abundance until they were no longer detectable at day 18. These results indicate that gangliosides with high sialic acid content undergo stage-specific developmental cycles in the chick cornea. Furthermore, the data suggest that phosphatidylserine content may be a sensitive biochemical measure of corneal innervation.