EXPERIMENTAL MODIFICATION OF VITELLOGENESIS IN JAPANESE-QUAIL BY TRYPAN BLUE IN-VIVO

Ovaries of adult Japanese quails were exposed in vivo to the acid bisa zo dye trypan blue (TB) which binds to plasma albumin, the plasma prec ursor of the yolk protein alpha-livetin. By a combination of fluoresce nce microscopy and electron microscopy alpha-livetin could be localize d in the subdroplets of intermediary and yellow yolk spheres. Trypan b lue alters vitellogenesis in the non-disc region of follicles in rapid growth in a reversible and dose-dependent way. Less yolk is produced over 24 h and its morphology is different when compared to controls. T his yolk is similar to yolk of the germinal disc region where vitellog enesis is known to be inhibited physiologically. Several ultrastructur al features of the germinal disc region are also found in the non-disc region of TB-exposed follicles. Our results suggest that the morpholo gy of yellow yolk is linked to the rate of deposition. We propose that the inhibitory action of TB on vitellogenesis can be explained by a d efective-receptor-ligand dissociation in endosomes.