Characterization, fate, and function of hamster cortical granule components

Little is known about the composition and function of mammalian cortical gr anules. In this study, lectins were used as tools to: (1) estimate the numb er and molecular weight of glycoconjugates in hamster cortical granules and show what sugars are associated with each glycoconjugate; (2) identify cor tical granule components that remain associated with the oolemma, cortical granule envelope, and/or zona pel lucida of fertilized oocytes a nd preimpl antation embryos; and (3) examine the role of cortical granule glycoconjuga tes in preimplantation embryogenesis. Microscopic examination of unfertiliz ed oocytes revealed that the lectins PNA, DBA, WGA, RCA(120), Con A, and LC A bound to hamster cortical granules. Moreover, LCA and Con A labeled the z ona pellucida, cortical granule envelope, and plasma membrane of fertilized and artificially activated oocytes and two and eight cell embryos. Lectin blots of unfertilized oocytes had at least 12 glycoconjugates that were rec ognized by one or more lectins. Nine of these glycoconjugates are found in the cortical granule envelope and/or are associated with the zona pellucida and plasma membrane following fertilization. In vivo functional studies sh owed that the binding of Con A to one or more mannosylated cortical granule components inhibited blastomere cleavage in two-cell embryos. Our data sho w that hamster cortical granules contain approximately 12 glycoconjugates o f which nine remain associated extracellularly with the fertilized oocyte a fter the cortical reaction and that one or more play a role in regulating c leavage divisions. (C) 2001 Wiley-Liss, Inc.