Multinucleate oocytes of F. pygmaeus. (A) Diagrams of oocytes. Small oocytes contain about 2000 germinal vesicles of similar diameter, depicted in blue. As oocytes grow, germinal vesicles located toward the periphery enlarge, whereas the centrally located ones remain small. With vitellogenesis, the number of germinal vesicles decreases until only one remains in the full grown oocyte. (B) Germinal vesicles (gv) of different sizes, extruded from a living oocyte. Nucleoli (nu) occur in large and small gvs. (C) Section through a multinucleate oocyte with gvs of various sizes.