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The mouse egg's zona pellucida (ZP) is composed of three glycoproteins, called ZP1, ZP2, and ZP3, that migrate as relatively broad, single bands on SDS–PAGE. The glycoproteins are organized within the ZP as a network of long interconnected fibrils that exhibit a structural periodicity. Here, ZP2 and ZP3 were purified by HPLC to homogeneity and analyzed by Blue Native‐ (BN‐) PAGE and transmission electron microscopy (TEM), as well as by SDS–PAGE. As opposed to SDS–PAGE, BN–PAGE, and TEM permit analysis of ZP2 and ZP3 under non‐denaturing conditions. ZP2 and ZP3 migrate on BN–PAGE, not as single bands, but as several discrete oligomers that give rise to larger structures which remain at the origin of the gel. Consistent with this, ZP2 and ZP3 are visualized by TEM as long interconnected fibrils that consist of contiguous beads. Therefore, under non‐denaturing conditions both purified ZP2 …