Changes in the electrophoretic pattern of yolk proteins during vitellogenesis in the gilthead sea bream Sparus aurata L.

To some extent, oocyte growth within a follicle is due, as well as to the accumulation of normal cytoplasmic components, to that of the cortical alveoli, and of hepatic-cerived protein (vitellogenins). Yolk proteins of pre-maturational oocytes at different stages and ovulated eggs were compared by SDS-gel electrophoresis. The largest components stained by Coomassie Blue and those stained by Stains-all, which had formed during vitellogenesis, either disappeared or diminished, whilst smaller components appeared. The distinct changes in yolk-protein banding patterns during oocyte maturation are suggestive of extensive secondary proteolysis of yolk proteins