The mature Xenopus oocyte is far from homogeneous. Various components have spatially specific distributions. Among the most obvious are yolk platelets. Varying in size, density and location, yolk platelets are one of the most obvious indications that the oocyte has lots of structure. There are other inhomogeneities in the oocyte, however. These include maternal messenger RNAs, such as Vg1, which localizes to the extreme vegetal pole of the oocyte.
A schematic diagram of the yolk distribution in the mature Xenopus oocyte.