The Differentiation of the Vitelline Envelope of Xenopus Oocytes*: (xenopus/oocyte/vitelline envelope/differentiation/fucosyl glycoproteins).

We have studied the differentiation of the vitelline envelope (V.E.) of the oocyte of the anuran Xenopus laevis. The V.E. precursor material is synthesized by the oocyte concomitantly with the onset of vitellogenesis, and its extrusion reaches a maximum at late vitellogenesis. Oocytes at different stages of growth were incubated in L-[ H]fucose and the progress of incorporation was followed by kinetic and histoautoradiographic analysis. We found that the highest overall rate of incorporation was exhibited by the vitellogenic oocytes. These oocytes showed clusters of grains in the perinuclear and in the cortical areas. The highest accumulation of grains in the V.E. was associated with the late vitellogenic stage, when the differentiation of the V.E. was almost complete. L-[ H]Fucose labelled glycoproteins have been identified by electrophoretic analysis of V.E. prepared from late vitellogenic stages.