[Neuraminic acid content of fish eggs during early ontogenesis]

The content of neuraminic acid (NA) of different developmental stages of trout eggs was determined. 1. The total NA increases from about 13 μg NA per egg (6-8 weeks before spawning) to 50 μg directly before spawning until hatching. 2. In freshly hatched fish larvae the NA-content is decreased to about 40 per cent as compared with stages before hatching. 3. The ratio of bound to free NA decreases from values of about 13.5 (6-8 weeks before spawning) to 0.85-1.2 at the hatching-stage. 4. The bound NA is almost entirely bound to sialo-glycoproteins.